V - volume of hydrochloric acid taken to perform the analysis, cm 3;
p - density of the analyzed hydrochloric acid, g/cm3.
The result of the analysis is taken as the arithmetic mean of the results of three parallel measurements, the differences between which should not exceed 0.0003%. The results of the determination are rounded to 0.0001%.
The permissible differences between the results obtained in two laboratories should not exceed 0.0005%.
The absolute total error of determination is in the range of ±0.2 A, where A is the result of determination at a confidence level P = 0.95 .
6.9 Determination of the mass fraction of arsenic
6.9.1 The method is based on the distillation of arsenic compounds in the form of arsenic hydrogen and its further interaction with mercury bromide to form an orange compound, the color intensity of which is compared with the color intensity of a standard containing 0.002 and 0.004 mg of arsenic. The sensitivity of the method is 0.0001%.
6.9.2 Equipment, solutions, reagents:
- flasks Kn-2-100, 250 according to GOST 25336;
- pipettes 1.5-2.10 according to GOST 29169;
- volumetric flasks 2.2-100, 1000 according to GOST 1770;
- a device for distilling arsenic according to GOST 10485;
- cylinder 1.2-100 according to GOST 1770;
- hydrochloric acid according to GOST 3118, chemically pure, solution with a mass fraction of 15%;
- tin dichloride according to the current regulatory documentation - solution with a mass fraction of 10%;
- granulated tin in accordance with current regulatory documentation;
- granulated zinc in accordance with current regulatory documentation;
- arsenic solution with a mass concentration of 1 mg/cm 3, prepared according to GOST 4212;
- distilled water according to GOST 6709;
- bromine-mercury paper, prepared according to GOST 4517.
6.9.3 Preparation for analysis
6.9.3.1 Preparation of stannous chloride solution
10 g of the reagent is dissolved in 15 cm 3 of hydrochloric acid (if necessary, the conical flask is heated). The solution is transferred to a volumetric flask with a ground stopper with a capacity of 100 cm 3, 0.5 g of granulated tin is added, and the volume is adjusted to the mark with water. Weighing results are recorded to the second decimal place.
6.9.3.2 Preparation of arsenic solution with a concentration of 0.001 mg/cm3
Pipette 1 cm 3 of arsenic solution, prepared according to GOST 4212, into a volumetric flask with a capacity of 100 cm 3, bring the volume of the solution to the mark with water and mix. Using a pipette, 10 cm 3 of the resulting solution is taken, transferred to a volumetric flask with a capacity of 100 cm 3, the volume is adjusted to the mark with water and mixed. The solution is used freshly prepared.
6.9.4 Conducting analysis
The determination is carried out according to GOST 10485. To do this, 1.7 cm 3 (2 g) of the analyzed hydrochloric acid is taken with a pipette and placed in a flask of an instrument for determining arsenic containing 30 cm 3 of distilled water. At the same time, a reference solution is prepared: 30 cm 3 of distilled water is placed in the instrument flask and 2 cm 3 is added with a pipette to one flask, and 4 cm 3 of arsenic solution with a concentration of 0.001 mg/cm 3 is added to the second flask.
Then 7 cm 3 of concentrated hydrochloric acid and 0.5 cm 3 of tin dichloride solution are added to both flasks. Add 5 g of zinc to each flask, and bromine-mercury paper to the nozzle. Quickly close the stopper with a nozzle, carefully mix with a rotational motion and leave alone for (90±10) minutes. After this time, the bromine-mercury papers are removed from the instruments and the color intensity of the paper is compared with the analyzed solution and the reference solution.
The product meets the established standard if the color intensity of the paper from the analyzed hydrochloric acid solution is the same as or less than the intensity of the reference solution.
6.10 Determination of mass fraction of mercury
6.10.1 Determination of the mass fraction of mercury using the "Mercury-101" analyzer
6.10.1.1 The method is based on measuring the concentration of metallic mercury vapor in the gas phase by atomic absorption of the resonance radiation of its atoms at a wavelength of 253.7 nm.
Sample preparation involves boiling it in the presence of potassium bichromate to remove chlorine gas. Measuring range from 0.5% to 5·10 -4%.
6.10.1.2 Equipment, reagents, solutions:
- mercury analyzer type "Mercury-101" (or other device with similar metrological characteristics);
- flasks 2-100, 1000 according to GOST 1770;
- pipettes 1, 2, 6, 7-1, 2, 5, 10 according to GOST 29169;
- cylinder 3-100 according to GOST 1770;
- flasks Kn-1.50 according to GOST 25336;
- nitric acid according to GOST 4461, chemical grade;
- potassium dichromate according to GOST 4220, solution with a concentration of 40 g/dm 3 (prepared as follows: 4 g of the reagent is dissolved in 100 cm 3 of water; stored in a flask with a ground stopper; weighing results are recorded accurate to the second decimal place);
- the dilution solution is prepared as follows: place 50 cm 3 of nitric acid, 5 cm 3 of potassium dichromate solution into a volumetric flask with a capacity of 1000 cm 3 and add water to the mark;
- tin dichloride, a solution with a mass fraction of 10%, is prepared as follows: 10 g of the reagent is dissolved in a volumetric flask with a capacity of 100 cm 3 in 25 cm 3 of hydrochloric acid at boiling until the reagent is completely dissolved; after cooling to (20±5) °C, the volume is adjusted to the mark with water; the freshly prepared solution is cleaned of mercury by blowing with air for at least 5 minutes; use on the day of preparation; weighing results are recorded accurate to the second decimal place;
- mercury (II) nitrate 1-aqueous according to GOST 4520, chemically pure, solution of concentration 0.01 μg/cm 3 (the initial solution of concentration 1 mg/cm 3 is prepared according to GOST 4212 - solution A; a solution of concentration 0 is prepared by appropriate dilution .01 μg/cm 3 , for which 10 cm 3 of solution A is placed in a volumetric flask with a capacity of 100 cm 3 and the volume is adjusted to the mark with the dilution solution - solution B with a concentration of 100 μg/cm 3 ; good for 3 months; 1 cm 3 of solution B placed in a volumetric flask with a capacity of 100 cm 3 and the volume is brought to the mark with a dilution solution - solution G with a concentration of 1 μg/cm 3, good for 7 hours; 10 cm 3 of solution G is placed in a volumetric flask with a capacity of 100 cm 3 and the volume is brought to a volume with a dilution solution marks - working solution with a concentration of 0.01 μg/cm 3 , good for 7 hours);
- distilled water according to GOST 6709.
6.10.1.3 Safety requirements when working with the “Mercury-101” device
Personnel who have studied the design of the device and have been instructed to work with electrical devices operating at a voltage of 1000 V are allowed to work. It is necessary to check the reliability of grounding before work. When repairing or replacing reagents, the device should be disconnected from the network.
6.10.1.4 Preparation for analysis
The device is calibrated according to the passport (technical description and instructions) attached to the device.
6.10.1.5 Sample preparation
10 g of hydrochloric acid to be analyzed is placed in two pre-weighed conical flasks containing (20±1) cm 3 of distilled water. Weighing results are recorded to the second decimal place. Then up to 1 cm 3 of potassium bichromate solution is added to the flasks and the samples are boiled for 5 minutes, provided that the yellow color of potassium bichromate is preserved. Otherwise, add a solution of potassium dichromate in portions of 0.5 cm 3. After cooling, the solution is quantitatively transferred into a volumetric flask with a capacity of 100 cm 3 and adjusted to the mark with water (solution D).
At the same time, under the same conditions, a control experiment is carried out, for which 20 cm 3 of water and the same amount of potassium dichromate that was used in preparing the sample are introduced into the same conical flask. Boil for 5 minutes. After cooling, the solution is transferred to a 100 cm 3 volumetric flask (solution E).
2 cm 3 of solution D is placed in a volumetric flask with a capacity of 100 cm 3 and the volume is adjusted to the mark with a dilution solution (solution D 1). Solution E is also diluted and solution E 1 is obtained.
6.10.1.6 Conducting analysis.
Solutions D 1 and E 1 are placed sequentially, starting with the control one, into the reactor of the analyzer and the measurement is carried out according to the instructions for the device.
The result of the analysis is taken as the arithmetic mean of the analyzer readings for two parallel samples (a), the discrepancy between which does not exceed ±(10 + 0.05), where is the arithmetic mean of the analyzer readings for two parallel samples.
6.10.1.7 Processing results
Mass fraction of mercury X 4
%, calculated using the formula.
GOST 857-95
INTERSTATENUMBER STANDARD
ACIDSALT
SYNTHETIC TECHNICAL
Ttechnical conditions
INTERSTATE COUNCIL
ON STANDARDIZATION, METROLOGY AND CERTIFICATION
Minsk
Preface
1 DEVELOPED by the Kyiv Research Institute of Synthesis and Ecology (KNII "SINTECO")
INTRODUCED by the Technical Secretariat of the Interstate Council for Standardization, Metrology and Certification
2 ADOPTED by the Interstate Council for Standardization, Metrology and Certification (Protocol No. 7 of April 26, 1995)
3 Appendix B of this standard contains the full authentic text of the international standard ISO 905-76 “Hydrochloric acid for industrial use. Estimation of hydrochloric acid concentration by measuring density"
4 By Decree of the Committee of the Russian Federation on Standardization, Metrology and Certification dated February 27, 1996 No. 117, the interstate standard GOST 857-95 was put into effect directly as a state standard of the Russian Federation on January 1, 1997.
6 REPUBLICATION. November 2005
GOST 857-95
INTERSTATENUMBER STANDARD
ACIDSALT SYNTHETIC TECHNICAL
Ttechnical conditions
Synthetic hydrochloric acid for industrial use.
Specifications
Ddate of introduction 1996-07-01
1 area of use
This standard applies to technical synthetic hydrochloric acid produced by the absorption of hydrogen chloride with water, formed by the interaction of evaporated, electrolytic chlorine, chlorine liquefaction exhaust gases with hydrogen.
Technical synthetic hydrochloric acid is used in the chemical, medical, food industries, non-ferrous and ferrous metallurgy.
Formula: HCl.
Molecular mass (according to international atomic masses 1985) - 36.46.
Mandatory requirements for products aimed at ensuring their safety for life and health of the population and environmental protection are given in Table 1, paragraphs 6 and 7.
GOST 12.1.005-88 System of occupational safety standards. General sanitary and hygienic requirements for the air in the working area
GOST 12.1.044-89 (ISO 4589-84) System of occupational safety standards. Fire and explosion hazard of substances and materials. Nomenclature of indicators and methods for their determination
GOST 12.4.013-85* System of occupational safety standards. Safety glasses. General technical conditions
* GOST R 12.4.013-97 is in force on the territory of the Russian Federation.
GOST 12.4.021-75 System of occupational safety standards. Ventilation systems. General requirements
GOST 12.4.103-83 System of occupational safety standards. Special protective clothing, personal protective equipment for legs and arms. Classification
GOST 12.4.121-83 System of occupational safety standards. Industrial filter gas masks. Specifications
GOST 61-75 Acetic acid. Specifications
GOST 199-78 Sodium acetate 3-water. Specifications
GOST 1770-74 Laboratory glassware. Cylinders, beakers, flasks, test tubes. General technical conditions
GOST 2874-82 ** Drinking water. Hygienic requirements and quality control
** GOST R 51232-98 is in force on the territory of the Russian Federation.
GOST 3118-77 Reagents. Hydrochloric acid. Specifications
GOST 3760-79 Reagents. Ammonia aqueous. Specifications
GOST 4204-77 Reagents. Sulfuric acid. Specifications
GOST 4212-76 Reagents. Preparation of solutions for colorimetric and nephelometric analysis
GOST 4220-75 Reagents. Potassium dichromate. Specifications
GOST 4328-77 Reagents. Sodium hydroxide. Specifications
GOST 4461-77 Reagents. Nitric acid. Specifications
GOST 4478-78 Reagents. Sulfosalicylic acid. Specifications
GOST 4517-87 Reagents. Methods for preparing auxiliary reagents and solutions used in analysis
GOST 4520-78 Reagents. Mercury (II) nitrate 1-aqueous. Specifications
GOST 4919.1-77 Reagents and highly pure substances. Methods for preparing indicator solutions
GOST 5230-74 Reagents. Mercury oxide is yellow. Specifications
GOST 5456-79 Reagents. Hydroxylamine hydrochloride. Specifications
GOST 6709-72 Distilled water. Specifications
GOST 9557-87 Flat wooden pallet measuring 800×1200 mm. Specifications
GOST 10485-75 Reagents. Methods for determining arsenic impurities
GOST 10555-75 Reagents and highly pure substances. Colorimetric methods for determining the content of iron impurities
GOST 10652-73 Reagents. Disodium salt of ethylenediamine-N,N,N′,N′-tetraacetic acid 2-water (trilon B)
GOST 14192-96 Marking of cargo
GOST 18300-87 Rectified technical ethyl alcohol. Specifications
GOST 18573-86 Wooden boxes for chemical industry products. Specifications
GOST 19433-88 Dangerous goods. Classification and labeling
GOST 19908-90 Crucibles, bowls, beakers, flasks, funnels, test tubes and tips made of transparent quartz glass. General technical conditions
GOST 20015-88 Chloroform. Specifications
GOST 21650-76 Means for fastening packaged cargo in transport packages. General requirements
GOST 24104-88* General purpose and standard laboratory scales. General technical conditions
GOST 24597-81 Packages of packaged piece goods. Main parameters and dimensions
GOST 25336-82 Laboratory glassware and equipment. Types, main parameters and sizes
GOST 25794.1-83 Reagents. Methods for preparing titrated solutions for acid-base titrations
GOST 26319-84 Dangerous goods. Package
GOST 26663-85 Transport packages. Formation using packaging tools. General technical requirements
GOST 29169-91 (ISO 648-77) Laboratory glassware. Single mark pipettes
GOST 29251-91 (ISO 385-1-84) Laboratory glassware. Burettes. Part 1. General requirements
3 Technical requirements
3.1 Technical synthetic hydrochloric acid must be manufactured in accordance with the requirements of this standard according to technological regulations approved in the prescribed manner.
3.2 Characteristics
3.2.1 Hydrochloric acid is produced in two grades: A and B.
3.2.2 In terms of physicochemical parameters, technical synthetic hydrochloric acid must comply with the standards specified in Table 1.
3.3 Marking
3.3.1 Transport marking of barrels and bottles - in accordance with GOST 14192 with the application of the handling sign “Sealed packaging”.
Marking characterizing the transport danger of the cargo - according to GOST 19433 (class 8, subclass 8.1, classification number 8172, drawing 8/6 a), UN serial number 1789.
Table 1
| Indicator name | Standard for the brand | Analysis methods |
|||
| A OKP 21 2211 0100 | B OKP 21 2211 0200 |
||||
| premium grade OKP 21 2211 0220 | first grade OKP 21 2211 0230 |
||||
| 1 Appearance | Transparent colorless or yellowish liquid | Clear yellow liquid | |||
| 2 Mass fraction of hydrogen chloride, %, not less | |||||
| 3 Mass fraction of iron (Fe), %, no more | |||||
| 4 Mass fraction of residue after calcination, %, no more | |||||
| 5 Mass fraction of free chlorine, %, no more | |||||
| 6 Mass fraction of arsenic (As), %, no more | |||||
| 7 Mass fraction of mercury (Hg), %, no more | |||||
Notes
1 The mass fraction of mercury is normalized in the acid obtained from hydrogen and chlorine mercury electrolysis.
2 It is allowed for the food industry, by agreement with the consumer, to produce acid with a mass fraction of hydrogen chloride of no more than 26%.
3 In the acid supplied for pickling metals, the mass fraction of iron and residue after calcination is not standardized.
4 By agreement with the consumer, a mass fraction of hydrogen chloride of at least 30% is allowed in acid of both brands.
3.3.2 A label made of plywood or thick cardboard, protected by an acid-resistant and moisture-proof shell, is attached to each barrel or bottle, on which data characterizing the packaged product is applied:
Name of the enterprise and (or) its trademark;
Name of the product, its brand, grade;
Designation of this standard;
Gross and net weight;
The number of the barrel or bottle and the total number of them in the batch.
3.3.3 Signs and inscriptions on tanks and containers are applied in accordance with the requirements of the “Rules for the Transportation of Dangerous Goods” (Part 2, Section 41, 1987, Moscow).
3.4 Package
3.4.1 Technical synthetic hydrochloric acid is poured into special rubberized tanks of the sender or recipient, rubberized containers, polyethylene barrels with a capacity of 50 dm 3 and glass bottles with a capacity of 20 dm 3 in accordance with the current regulatory documentation.
Glass bottles are packed in boxes of type V-1, number 3-2 according to GOST 18573. Packaging must comply with GOST 26319.
3.4.2 It is allowed to pour the product into tanks and containers with hydrochloric acid residue if analysis of the residue confirms that its quality meets the requirements of this standard. Otherwise, the remaining hydrochloric acid is removed and the tank or container is washed.
Barrels and bottles must be dry and clean.
3.4.3 Filling hatches of tanks, containers and barrel plugs must be sealed with rubber or polyethylene gaskets, both when sent to consumers (filled with acid) and when empty containers are returned to the supplier.
The necks of bottles, sealed with ground glass stoppers or screw caps, should be wrapped in plastic film and tied with twine.
3.4.4 The level (degree) of filling of tanks, containers, barrels and bottles is calculated taking into account the maximum use of the carrying capacity (capacity) and volumetric expansion of the product with a possible temperature difference along the route.
4 Safety requirements
4.1 Technical synthetic hydrochloric acid is a caustic liquid, chemically stable.
In air it “smoke” as a result of the release of hydrogen chloride and its attraction of air moisture with the formation of acid fog.
Metals located in the voltage series to the left of hydrogen (Al, Zn, Fe, Co, Ni, Pb, etc.) displace it from hydrochloric acid, which can lead to the formation of explosive hydrogen-air mixtures.
Safety measures include eliminating contact of hydrochloric acid with these metals through anti-corrosion coatings, nitrogen purging and testing the gas phase from equipment and pipelines for explosiveness before hot work.
4.2 According to GOST 12.1.044, the product is classified as a non-flammable substance.
4.3 Hydrochloric acid mist irritates the upper respiratory tract and mucous membranes of the eyes. In case of contact with skin, it causes burns.
4.4 According to GOST 12.1.005, the maximum permissible concentration (MPC) of hydrochloric acid vapor in the air of the working area is 5 mg/m 3, hazard class - 2 (highly hazardous substances);
The maximum permissible concentration of chlorine in the air of the working area is 1 mg/m 3, hazard class - 2 (highly hazardous substances).
Chlorine and hydrochloric acid have a highly targeted mechanism of action. When working with them, special skin and eye protection is required.
Determination of hydrogen chloride, chlorine - in accordance with current regulatory documentation.
Sampling points must be agreed upon with local sanitary and epidemiological authorities. Assessment of the state of the air environment in the simultaneous presence of chlorine and hydrogen chloride - in accordance with GOST 12.1.005.
4.5 Technological processes for the production and use of hydrochloric acid and the production equipment used must comply with the requirements of sanitary regulations No. 1042-73.
Production premises must be equipped with ventilation in accordance with GOST 12.4.021 and SNiP 2.04.05-91 and a water supply that meets the requirements of GOST 2874.
4.6 All work with hydrochloric acid must be carried out in special clothing of type K50 in accordance with GOST 12.4.103 and in safety glasses of type G in accordance with GOST 12.4.013.
All workers must be provided with industrial filter gas masks of grade B (RPE FGP, FG-130) in accordance with GOST 12.4.121.
4.7 In the event of a spill, wash off hydrochloric acid from floor surfaces and equipment with plenty of water or an alkaline solution. Acidic wastewater must be neutralized at local treatment plants before entering the general plant sewage system.
4.8 Fire extinguishing is carried out using sprayed water and air-mechanical foam.
4.9 The substandard product is neutralized with an alkali solution. Gas emissions are captured and neutralized.
5 Acceptance
5.1 Technical synthetic hydrochloric acid must be presented for acceptance in batches.
A batch is considered to be any quantity of hydrochloric acid, homogeneous in its qualitative composition, documented in one quality document.
The quality document must contain the following data:
Name and (or) trademark of the manufacturer;
Name of the product and its brand, grade, standard designation;
Batch number, date of manufacture;
Tank number, number of containers, barrels, bottles;
Net weight;
Classification code according to GOST 19433;
The results of the analysis or confirmation of quality compliance with the requirements of this standard.
5.2 To check the quality of hydrochloric acid, acceptance and periodic tests are carried out.
5.3 The manufacturer determines the mass fraction of arsenic periodically once a quarter.
5.4 During acceptance tests at the manufacturer, samples are taken from a commercial tank intended for filling containers.
To check the quality of hydrochloric acid, samples are taken from the consumer:
From each tank and container;
From 10% of barrels, bottles, but not less than three for batches of less than 10 barrels, bottles.
5.5 If unsatisfactory analysis results are obtained for at least one of the indicators, a repeat analysis is carried out on a double sample or a newly selected sample from a tank, container, barrels, bottles.
The results of the re-analysis apply to the entire batch.
6 Methods of analysis
6.1 Point samples from the reservoir and tank are taken by slowly immersing a sampler of any design, made of acid-resistant materials, to the bottom of the reservoir or tank.
Point samples from barrels, bottles and containers are taken using a glass or polyethylene tube with a diameter of 10 - 15 mm with an extended end.
The pooled sample is obtained by mixing equal volumes of spot samples.
6.2 From the thoroughly mixed combined sample, a sample for analysis with a volume of at least 1 dm 3 is taken, which is placed in a dry, clean bottle with a ground stopper or a plastic jar with a screw cap. A label is placed on the bottle or plastic jar indicating:
Manufacturer and product names;
Designations of this standard, brand and grade;
Dates and places of sampling;
Batch numbers and production dates;
Last name of the person who took the sample.
6.3 General instructions for conducting analysis
When performing the analysis, the air temperature should be (20 ± 5) °C.
When weighing, general-purpose laboratory scales in accordance with GOST 24104 of accuracy classes 2 and 4 with the largest weighing limits of 200 and 500 g should be used.
It is allowed to use imported utensils with an accuracy class and reagents with a quality no lower than domestic ones.
It is allowed to determine the density of hydrochloric acid according to Appendix B.
6.4 Defining Appearance
The appearance is determined visually in the transmitted light of a column of liquid poured into a cylinder 1.2-100 according to GOST 1770.
6.5 Determination of the mass fraction of hydrogen chloride
6.5.1 The determination method is based on the reaction of neutralization of hydrogen ions with sodium hydroxide:
H + + OH - = H 2 O. (1)
Methyl orange is used as an indicator.
6.5.2 Equipment, reagents, solutions:
Burette 1, 2, 3-25-0.1 according to GOST 29251;
Flask Kn-1.2-100, 250-1 according to GOST 25336;
Flask 2-250, 1000 according to GOST 1770;
Pipette 2-20 according to GOST 29169;
Cylinder 1.2-25 according to GOST 1770;
Sodium hydroxide according to GOST 4328, chemical grade, concentration solution c(NaON) = 0.1 mol/dm 3, prepared according to GOST 25794.1;
Methyl orange (indicator), solution with a mass fraction of 0.1%; an aqueous solution is prepared according to GOST 4919.1;
Distilled water in accordance with GOST 6709 and not containing carbon dioxide is prepared in accordance with GOST 4517.
6.5.3 Conducting analysis
In a pre-weighed flask with a ground stopper with a capacity of 100 cm 3 and containing 20 cm 3 of water, place 3 cm 3 of the acid being analyzed and weigh again (the weighing result is recorded accurate to the fourth decimal place). The solution is transferred quantitatively into a volumetric flask with a capacity of 250 cm 3, rinsed repeatedly with distilled water, poured into a volumetric flask, the volume is adjusted to the mark with water and mixed. Using a pipette, 20 cm 3 of the resulting hydrochloric acid solution is taken into a conical flask with a capacity of 250 cm 3, 25 cm 3 of water, 2-3 drops of methyl orange indicator are added and titrated with a solution of sodium hydroxide until the red color turns yellow.
6.5.4 Processing results
Mass fraction of hydrogen chloride X, %, calculated by the formula
Where V- volume of sodium hydroxide solution concentration exactly c(NaOH) = 0.1 mol/dm 3, used for titration, cm 3;
V 1 - volume of solution of the analyzed hydrochloric acid taken to perform the analysis, cm 3;
m- mass of the flask with water, g;
m 1 - mass of the flask with water and the acid being analyzed, g;
0.003646 - mass of hydrogen chloride corresponding to 1 cm 3 sodium hydroxide solution, concentration exactly c(NaOH) = 0.1 mol/dm3, g/cm3.
The result of the analysis is taken as the arithmetic mean of the results of two parallel measurements, the permissible differences between which should not exceed 0.3% with a confidence level P = 0,95.
The permissible differences between the results obtained in two laboratories should not exceed 0.6%. Relative total error of determination ±2% with confidence level P = 0,95.
6.6 Determination of the mass fraction of iron
6.6.1 The mass fraction of iron is determined in hydrochloric acid after diluting the sample without preliminary neutralization. Neutralization is carried out after the introduction of sulfosalicylic acid, that is, neutralization and the formation of iron sulfosalicylate complex 3, colored yellow in a slightly alkaline environment (pH 8.0 - 11.5), occur simultaneously. The intensity of light absorption of the formed complex is measured using a photoelectrocolorimeter. Measuring range 5 · 10 -4 - 2.0 · 10 -2%.
6.6.2 Equipment, solutions, reagents:
Photoelectric laboratory colorimeter FEK-56M, KFK or another type, providing the specified sensitivity and accuracy;
Mechanical stopwatch of any brand;
Cup SZ-14/8 according to GOST 25336;
Flasks 1.2-50, 100, 250 and 1000 cm 3 according to GOST 1770;
Pipettes 1, 2, 5, 7-1, 25, 2, 5, 10 according to GOST 29169;
Hydrochloric acid according to GOST 3118, chemically pure, aqueous solution (1:1);
Aqueous ammonia according to GOST 3760, analytical grade, solution with a mass fraction of 25%;
Sulfosalicylic acid according to GOST 4478, analytical grade, solution concentration 100 g/dm 3 ;
Ferroammonium alum in accordance with current regulatory documentation;
An iron solution with a concentration of 1 mg/cm 3 is prepared according to GOST 4212; a solution with a concentration of 10 μg/cm 3, freshly prepared, is prepared by dilution;
6.6.3 Preparation for analysis
6.6.3.1 Preparation of sulfosalicylic acid solution
Transfer 10 g of sulfosalicylic acid into a 100 cm3 volumetric flask, dissolve, adjust the volume to the mark with water, and mix. Weighing results are recorded to the second decimal place.
6.6.3.2 Preparation of calibration solutions and calibration of the photoelectric colorimeter.
Calibration and determination are carried out according to GOST 10555 using the sulfosalicylic method.
30 cm 3 of distilled water is introduced into volumetric flasks with a capacity of 50 cm 3, and 1 cm 3 of hydrochloric acid solution, 1.0, is added with a pipette. 2.0; 3.0; 4.0; 6.0 cm 3 of iron solution with a concentration of 10 μg/cm 3 , 2 cm 3 of sulfosalicylic acid solution and 5 cm 3 of ammonia solution. After adding each reagent, the solution is stirred. The volume of the solution is adjusted to the mark with water and mixed. At the same time, prepare a control solution: add 30 cm 3 of water, 1 cm 3 of hydrochloric acid into a volumetric flask with a capacity of 50 cm 3, add 2 cm 3 of sulfosalicylic acid solution and then proceed as described above.
The optical density of calibration solutions is measured after (10 ± 1) min in cuvettes with a light-absorbing solution layer thickness of 50 mm at a wavelength of 434 nm relative to the control solution. The instrument can be calibrated using the least squares method.
Based on the results obtained, a calibration graph is constructed, plotting the mass of iron introduced into the calibration solutions in micrograms on the abscissa axis, and the corresponding values of optical densities on the ordinate axis. The calibration schedule is checked once a quarter, as well as when replacing reagents or instruments.
6.6.4 Conducting analysis
A sample of the analyzed hydrochloric acid weighing (20 ± 1) g is transferred quantitatively into a volumetric flask with a capacity of 250 cm 3, rinsing the glass several times with water, the volume of the solution is adjusted to the mark with water and mixed. Weighing results are recorded to the second decimal place.
Using a pipette, 25 cm 3 is taken for grades A and B of the highest grade, and for grade B of the 1st grade - 2.5 cm 3 of the prepared solution, transferred to a volumetric flask with a capacity of 50 cm 3, 2 cm 3 of sulfosalicylic acid solution is added and mixed. Then add 10 cm 3 of ammonia solution, adjust the volume to the mark with water and mix.
The control solution is prepared as described in 6.6.3.2. After (10 ± 1) minutes, measure the optical density and, using the calibration graph, find the mass of iron in the analyzed solution in micrograms.
6.6.5 Processing results
Mass fraction of iron X 1,%, calculated by the formula
Where m 1 - mass of iron in the analyzed solution, found from the calibration curve, mcg;
m- mass of a sample of hydrochloric acid taken for analysis, g;
V- volume of hydrochloric acid solution obtained after diluting the mass of hydrochloric acid, cm 3;
V 1 - volume of dilute hydrochloric acid solution taken to perform the analysis, cm 3.
The result of the analysis is taken as the arithmetic mean of the results of two parallel measurements, the differences between which should not exceed 0.0005%. Determination results are rounded to the fourth decimal place.
Absolute total error of determination ±0.2A, where A is the result of determination with confidence probability P = 0,95.
( Amendment )
6.7 Determination of the mass fraction of residue after calcination
6.7.1 The mass fraction of the residue after calcination at 600 °C is measured by the gravimetric method. The detection range is from 0.005% to 0.100%.
6.7.2 Equipment, solutions and reagents:
Cylinder 2-100 according to GOST 1770;
Quartz cup type KP with a capacity of 100 cm 3 according to GOST 19908, platinum or porcelain;
Desiccator 2-190 mm, 250 mm according to GOST 25336;
Muffle furnace with a thermocouple, ensuring temperature maintenance (600 ± 10) °C;
Sulfuric acid according to GOST 4204, chemical grade;
Calcium chloride, calcined at 250 - 300 °C;
Hourglass at 5 minutes.
6.7.3 Preparation for analysis
The cup is calcined in a muffle furnace at a temperature of (600 ± 10) °C for (5 ± 1) minutes. The cup is then placed in a desiccator with calcium chloride and kept for (30 ± 5) minutes. The cooled cup is weighed. Weighing results are recorded to the fourth decimal place.
6.7.4 Conducting analysis
Using a cylinder, 85 cm 3 of the analyzed hydrochloric acid is taken and placed in a quartz cup, 1 drop of sulfuric acid is added and evaporated in a water bath almost to dryness. The cup with the residue is heated on an electric stove until the release of sulfuric acid vapors stops. Evaporation of the analyzed acid and decomposition of sulfuric acid can be carried out under an infrared lamp.
After this, the cup with the residue is transferred to a muffle furnace, preheated to (600 ± 10) °C, and calcined for (5 ± 1) minutes. Transfer the cup to a desiccator, leave for (30 ± 5) minutes and weigh.
6.7.5 Processing results
Mass fraction of residue after calcination X 2,%, calculated by the formula
Where m 1 - mass of the cup with the residue after calcination, g;
m- mass of an empty cup, g;
V- volume of hydrochloric acid sample taken for analysis, cm 3;
The result of the analysis is taken as the arithmetic mean of the results of two parallel measurements, the permissible differences between which should not exceed 0.0006%. The results of parallel determinations are rounded to 0.0001%, the result of the determination is 0.001%.
The permissible differences between the results obtained in two laboratories should not exceed 0.0008%. Absolute total error of determination ±0.0005% with confidence probability P = 0,95.
6.8 Determination of the mass fraction of free chlorine
6.8.1 The method is based on the oxidation reaction of methyl orange with chlorine:
(5)As a result of the oxidation of methyl orange, the color of its solutions becomes less intense. The intensity of the color depends on the order in which the solutions are mixed, so the hydrochloric acid to be analyzed is added last during stirring. The method is selective; iron (III) interferes with the determination. Measuring range 5 · 10 -4 - 8 · 10 -3%.
6.8.2 Equipment, reagents and solutions:
Photoelectric laboratory colorimeter KFK or another type, providing the specified sensitivity and accuracy;
Volumetric flasks 2-25, 1000 according to GOST 1770;
Pipettes 1.5-1.2 according to GOST 29169;
Hydrochloric acid according to GOST 3118, chemically pure, solution (1:2);
Methyl orange (indicator), a solution with a concentration of 0.1 g/dm3, is prepared as follows: 0.1 g of methyl orange is transferred to a volumetric flask with a capacity of 1000 cm3, the volume of the solution is adjusted to the mark with water and mixed. Weighing results are recorded to the second decimal place.
6.8.3 Preparation of calibration solutions and calibration of the photoelectric colorimeter
15 cm 3 of water is introduced into volumetric flasks with a capacity of 25 cm 3, and 2.0 is added with a pipette; 1.6; 1.2; 0.8; 0.4 cm 3 of methyl orange solution, which corresponds to 0; 10; 20; thirty; 40 mcg of chlorine, add 1 cm 3 of hydrochloric acid solution, bring the volume of the solution to the mark with water and mix. The optical density of the resulting solutions is measured on a photoelectrocolorimeter at a thickness of the light-absorbing layer of the solution of 10 mm and at a wavelength of 490 - 505 nm. The reference solution is distilled water.
Based on the data obtained, a calibration graph is constructed, plotting the mass of chlorine in micrograms on the abscissa axis, and the corresponding optical density value on the ordinate axis.
The calibration curve is checked once a quarter, as well as when replacing reagents or instruments.
The instrument can be calibrated using the least squares method.
6.8.4 Conducting analysis
Place 15 cm 3 of distilled water into a volumetric flask with a capacity of 25 cm 3, stirring vigorously, pipet 2 cm 3 of a solution of methyl orange, (0.5 - 2) cm 3 of the analyzed hydrochloric acid, adjust the volume of the solution with water to the mark and mix. The optical density of the resulting solution is measured using a photoelectrocolorimeter at a light-absorbing solution layer thickness of 10 mm and a wavelength of 490 - 505 nm. The reference solution is distilled water.
The mass of chlorine in micrograms in acid is found using a calibration curve.
6.8.5 Processing results
Mass fraction of free chlorine X 3,%, calculated by the formula
Where m- mass of chlorine in the analyzed hydrochloric acid, found from the calibration curve, mcg;
V- volume of hydrochloric acid taken to perform the analysis, cm 3;
ρ is the density of the analyzed hydrochloric acid, g/cm 3 .
The result of the analysis is taken as the arithmetic mean of the results of three parallel measurements, the differences between which should not exceed 0.0003%. Determination results are rounded to 0.0001%.
The permissible differences between the results obtained in two laboratories should not exceed 0.0005%.
The absolute total error of determination is in the range ±0.2A, where A is the result of determination at a confidence level P = 0,95.
6.9 Determination of the mass fraction of arsenic
6.9.1 The method is based on the distillation of arsenic compounds in the form of arsenic hydrogen and its further interaction with mercury bromide to form an orange compound, the color intensity of which is compared with the color intensity of a standard containing 0.002 and 0.004 mg of arsenic. The sensitivity of the method is 0.0001%.
6.9.2 Equipment, solutions, reagents:
Flasks Kn-2-100, 250 according to GOST 25336;
Pipettes 1.5-2.10 according to GOST 29169;
Volumetric flasks 2.2-100, 1000 according to GOST 1770;
Device for distilling arsenic according to GOST 10485;
Cylinder 1.2-100 according to GOST 1770;
Hydrochloric acid according to GOST 3118, chemically pure, solution with a mass fraction of 15%;
Tin dichloride according to current regulatory documentation - solution with a mass fraction of 10%;
Tin granulated in accordance with current regulatory documentation;
Granulated zinc in accordance with current regulatory documentation;
An arsenic solution with a mass concentration of 1 mg/cm 3 is prepared according to GOST 4212;
Distilled water according to GOST 6709;
Bromine-mercury paper, prepared according to GOST 4517.
6.9.3 Preparation for analysis
6.9.3.1 Preparation of stannous chloride solution
10 g of the reagent is dissolved in 15 cm 3 of hydrochloric acid (if necessary, the conical flask is heated). The solution is transferred to a volumetric flask with a ground stopper with a capacity of 100 cm 3, 0.5 g of granulated tin is added, and the volume is adjusted to the mark with water. Weighing results are recorded to the second decimal place.
6.9.3.2 Preparation of arsenic solution with a concentration of 0.001 mg/cm3
Pipette 1 cm 3 of arsenic solution, prepared according to GOST 4212, into a volumetric flask with a capacity of 100 cm 3, bring the volume of the solution to the mark with water and mix. Using a pipette, 10 cm 3 of the resulting solution is taken, transferred to a volumetric flask with a capacity of 100 cm 3, the volume is adjusted to the mark with water and mixed. The solution is used freshly prepared.
6.9.4 Conducting analysis
The determination is carried out according to GOST 10485. To do this, 1.7 cm 3 (2 g) of the analyzed hydrochloric acid is taken with a pipette and placed in a flask of an instrument for determining arsenic containing 30 cm 3 of distilled water. At the same time, a reference solution is prepared: 30 cm 3 of distilled water is placed in the instrument flask and 2 cm 3 is added with a pipette to one flask, and 4 cm 3 of arsenic solution with a concentration of 0.001 mg/cm 3 is added to the second flask.
Then 7 cm 3 of concentrated hydrochloric acid and 0.5 cm 3 of tin dichloride solution are added to both flasks. Add 5 g of zinc to each flask, and bromine-mercury paper to the nozzle. Quickly close the stopper with a nozzle, carefully mix with a rotational motion and leave alone for (90 ± 10) minutes. After this time, the bromine-mercury papers are removed from the instruments and the color intensity of the paper is compared with the analyzed solution and the reference solution.
The product meets the established standard if the color intensity of the paper from the analyzed hydrochloric acid solution is the same as or less than the intensity of the reference solution.
6.10 Determination of mass fraction of mercury
6.10.1 Determination of the mass fraction of mercury using the “Mercury-101” analyzer
6.10.1.1 The method is based on measuring the concentration of metallic mercury vapor in the gas phase by atomic absorption of the resonance radiation of its atoms at a wavelength of 253.7 nm.
Sample preparation involves boiling it in the presence of potassium bichromate to remove chlorine gas. Measuring range from 0.5% to 5 10 -4%.
6.10.1.2 Equipment, reagents, solutions:
Mercury analyzer type “Mercury-101” (or other device with similar metrological characteristics);
Flasks 2-100, 1000 according to GOST 1770;
Pipettes 1, 2, 6, 7-1, 2, 5, 10 according to GOST 29169;
Cylinder 3-100 according to GOST 1770;
Flasks Kn-1.50 according to GOST 25336;
Potassium dichromate according to GOST 4220, solution concentration 40 g/dm 3 (prepared as follows: 4 g of the reagent is dissolved in 100 cm 3 of water; stored in a flask with a ground stopper; weighing results are recorded accurate to the second decimal place);
The dilution solution is prepared as follows: place 50 cm 3 of nitric acid, 5 cm 3 of potassium dichromate solution into a volumetric flask with a capacity of 1000 cm 3 and add water to the mark;
Tin dichloride, a solution with a mass fraction of 10%, is prepared as follows: 10 g of the reagent is dissolved in a volumetric flask with a capacity of 100 cm 3 in 25 cm 3 of hydrochloric acid at boiling until the reagent is completely dissolved; after cooling to (20 ± 5) °C, the volume is adjusted to the mark with water; the freshly prepared solution is cleaned of mercury by blowing with air for at least 5 minutes; use on the day of preparation; weighing results are recorded accurate to the second decimal place;
Mercury (II) nitrate 1-aqueous according to GOST 4520, chemically pure, solution of concentration 0.01 μg/cm 3 (the initial solution of concentration 1 mg/cm 3 is prepared according to GOST 4212 - solution A; a solution of concentration 0 is prepared by appropriate dilution 01 μg/cm 3 , for which 10 cm 3 of solution A is placed in a volumetric flask with a capacity of 100 cm 3 and the volume is adjusted to the mark with the dilution solution - solution B with a concentration of 100 μg/cm 3 ; good for 3 months; 1 cm 3 of solution B is placed into a volumetric flask with a capacity of 100 cm 3 and bring the volume with the dilution solution to the mark - solution G with a concentration of 1 μg/cm 3, good for 7 hours; 10 cm 3 of solution G is placed in a volumetric flask with a capacity of 100 cm 3 and bring the volume with the dilution solution to the mark - working solution with a concentration of 0.01 μg/cm 3 , good for 7 hours);
Distilled water according to GOST 6709.
6.10.1.3 Safety requirements when working with the “Mercury-101” device
Personnel who have studied the design of the device and have been instructed to work with electrical devices operating at a voltage of 1000 V are allowed to work. It is necessary to check the reliability of grounding before work. When repairing or replacing reagents, the device should be disconnected from the network.
6.10.1.4 Preparation for analysis
The device is calibrated according to the passport (technical description and instructions) attached to the device.
6.10.1.5 Sample preparation
10 g of hydrochloric acid to be analyzed is placed into two pre-weighed conical flasks containing (20 ± 1) cm 3 of distilled water. Weighing results are recorded to the second decimal place. Then up to 1 cm 3 of potassium bichromate solution is added to the flasks and the samples are boiled for 5 minutes, provided that the yellow color of potassium bichromate is preserved. Otherwise, add a solution of potassium dichromate in portions of 0.5 cm 3. After cooling, the solution is quantitatively transferred into a volumetric flask with a capacity of 100 cm 3 and adjusted to the mark with water (solution D).
At the same time, under the same conditions, a control experiment is carried out, for which 20 cm 3 of water and the same amount of potassium dichromate that was used in preparing the sample are introduced into the same conical flask. Boil for 5 minutes. After cooling, the solution is transferred to a 100 cm 3 volumetric flask (solution E).
2 cm 3 of solution D is placed in a volumetric flask with a capacity of 100 cm 3 and the volume is adjusted to the mark with a dilution solution (solution D 1). Solution E is also diluted and solution E 1 is obtained.
6.10.1.6 Conducting analysis.
Solutions D 1 and E 1 are placed sequentially, starting with the control one, into the reactor of the analyzer and the measurement is carried out according to the instructions for the device.
The result of the analysis is taken as the arithmetic mean of the analyzer readings for two parallel samples (a), the discrepancy between which does not exceed ±(10 + 0.05), where is the arithmetic mean of the analyzer readings for two parallel samples.
6.10.1.7 Processing results
Mass fraction of mercury X 4,%, calculated by the formula
where is the arithmetic mean of the analyzer readings when measuring two parallel samples;
b- analyzer readings when measuring the control solution;
1/1000 - analyzer division value, µg;
m- mass of the analyzed acid sample, g (10 g).
Measurement results are rounded to 1 · 10 -5%.
Relative total measurement error ±10% with confidence level P = 0,95.
6.10.2 Determination of the mass fraction of mercury with dithizone
6.10.2.1 Equipment, solutions and reagents:
Aqueous ammonia according to GOST 3760, diluted 1:10;
Acetic acid according to GOST 61, chemical grade, concentration solution c(CH 3 COOH) = 1 mol/dm 3 ;
Sodium acetate according to GOST 199, analytical grade, concentration solution c(CH 3 COONa) = = 1 mol/dm 3 ;
An acetate buffer solution is prepared as follows: mix equal volumes of a solution of sodium acetate and a solution of acetic acid;
Hydroxylamine hydrochloric acid according to GOST 5456, analytical grade, aqueous solution with a mass fraction of 10%, freshly prepared;
Nitric acid according to GOST 4461, chemical grade;
Sulfuric acid according to GOST 4204, concentration solution c(1/2 H 2 SO 4) = 0.1 mol/dm 3;
Disodium salt of ethylenediamine-N,N,N′,N′-tetraacetic acid 2-water (trilon B) according to GOST 10652, concentration solution c(trilon B) = 0.1 mol/dm 3 ;
Chloroform according to GOST 20015;
Dithizone (diphenylthiocarbazone) according to current regulatory documentation, analytical grade. (a solution of dithizone in chloroform is prepared as follows: 0.2 g of dithizone is dissolved in 50 cm 3 of chloroform, transferred to a separating funnel with a capacity of 250 cm 3, add 100 cm 3 of ammonia solution (1:10) and shake; the ammonia solution is separated and transferred to another separating funnel; the operation is repeated three times; then the ammonia solution is acidified with sulfuric acid to pH 3 - 4 and dithizone is extracted three times with chloroform in portions of 20 cm 3; the chloroform extract is washed three times and diluted to 100 cm 3 with chloroform (solution A); save the solution dithizone under a layer of sulfuric acid solution in a dark, cool place; before use, solution A is diluted with chloroform so that the optical density of the solution, measured on a FEK-56 photoelectrocolorimeter or another brand device, at a wavelength of 580 - 587 nm (light filter 8 in a cuvette with a thickness light-absorbing layer of solution 0.5 cm) would be 0.75 (solution B);
Mercury oxide yellow according to GOST 5230;
A sample solution of mercury is prepared according to GOST 4212 or as follows: 0.1079 g of mercury oxide is dissolved by gently heating in 2 - 3 cm 3 of concentrated nitric acid and brought to 100 cm 3 with water; 1 cm 3 of the resulting solution contains 1 mg of mercury; by dilution prepare a solution containing 0.010 mg of mercury per 1 cm3; weighing results are recorded accurate to the fourth decimal place:
Universal indicator paper;
Distilled water according to GOST 6709;
Photoelectric colorimeter FEK-56 or a similar device with a specified accuracy and sensitivity;
Funnel VD1-250 according to GOST 25336;
Glass 1.2-100 according to GOST 25336.
6.10.2.2 Construction of a calibration graph
Into five separating funnels with a capacity of 250 cm 3 add 50 cm 3 of water, 1, 2, 3, 4 and 5 cm 3 of a diluted standard solution of mercury, which corresponds to 0.010; 0.020; 0.030; 0.040 and 0.050 mg of mercury, 5 cm 3 of Trilon B solution, 10 cm 3 of buffer solution, stirred for 1 minute, added 5 cm 3 of chloroform, stirred again for 1 minute and after settling, the chloroform was discarded. Then add 10 cm 3 of solution B (dithizone) and shake for 2 minutes. In parallel, a control solution containing all reagents except mercury is prepared under the same conditions.
After phase separation, the chloroform layer is separated and the optical density is measured on a photoelectrocolorimeter in a cuvette with a light-absorbing solution layer thickness of 0.5 cm with a light filter of 8. The reference solution is chloroform.
The calibration graph is plotted in the coordinates “optical density - mercury concentration, mg”.
6.10.2.3 Conducting analysis
5 cm 3 of the acid being analyzed is placed in a glass with a capacity of 100 cm 3 and water is added to 30 cm 3. The contents of the glass, after cooling, are slowly neutralized with an ammonia solution to pH 4 on indicator paper, water is added to 50 cm 3, 5 cm 3 of Trilon B solution, 10 cm 3 of a buffer solution, 1 - 3 cm 3 of hydroxylamine solution. After 10 minutes, the solution is transferred to a separating funnel with a capacity of 250 cm 3, 5 cm 3 of chloroform is added, mixed, and after settling, the chloroform layer is discarded.
To check the purity of the reagents, a control experiment is carried out, for which 50 cm 3 of water is placed in a separating funnel with a capacity of 250 cm 3, 5 cm 3 of Trilon B, 10 cm 3 of a buffer solution, and 1 - 3 cm 3 of hydroxylamine solution are introduced. After 10 minutes, 5 cm 3 of chloroform is added, stirred for 1 minute, and after settling, the chloroform layer is discarded. Extraction and determination of mercury are carried out as described in 6.10.2.2.
6.10.2.4 Processing results
Mass fraction X 6,%, calculated by the formula
Where m 1 - mass of mercury in the analyzed sample, found from the calibration curve, mg;
m 2 - mass of mercury found in the control experiment, mg;
V- volume of hydrochloric acid taken for analysis, cm 3;
ρ - density of hydrochloric acid, g/cm3.
The result of the analysis is taken as the arithmetic mean of the results of two parallel measurements, the permissible differences between which should not exceed 3 · 10 -5%.
In case of disagreement in assessing the quality of products, the mass fraction of mercury is determined using a chemical method.
7 Transportation and storage
7.1 Technical synthetic hydrochloric acid is transported in accordance with the rules for the transportation of dangerous goods:
In bulk in railway tanks (“Rules for the transportation of dangerous goods No. 340”, part 2, section 41);
Packed in barrels and bottles in boxes - by rail in covered wagons by wagonload (“Rules for the transportation of dangerous goods No. 340”, part 2, section 42);
Packed in containers, barrels, bottles - by road and water transport.
7.2 When shipped in packages, barrels and bottles are formed on flat wooden pallets in accordance with GOST 9557-87 in accordance with the requirements of GOST 21650, GOST 24597 and GOST 26663.
The weight of the package should not exceed the load capacity of the pallet.
In a railway car, packages are installed so that the capacity (carrying capacity) of the car is fully used.
7.3 Technical synthetic hydrochloric acid is stored in sealed containers of the manufacturer and consumer, made of materials resistant to hydrochloric acid.
The shelf life of the product is unlimited.
METHODOLOGY
measuring the mass concentration of hydrogen chloride in the air of industrial premises
A.1Purpose and scope
This technique is intended to measure the mass concentration of hydrogen chloride in the air of industrial premises.
The technique was carried out in accordance with current regulatory documentation.
Measurement range - (0.6 - 20) mg/m3.
Duration of analysis - 30 minutes.
A.2Method of measurement
To measure the mass concentration of hydrogen chloride in the air, a photocolorimetric analysis method is used, based on the interaction of chloride with mercury thiocyanate and the formation of a colored iron complex with thiocyanate.
Photometric conditions:
Wavelength - (480 ± 5) nm;
The thickness of the light-absorbing layer is 10 mm.
A.3Glassware, instruments and reagents:
General purpose laboratory scales of accuracy classes 2 and 4 according to GOST 24104 with maximum weighing limits of 200 and 500 g;
Photoelectric colorimeter of the KFK type or another type, providing the specified sensitivity and accuracy;
Flasks 2-100 (500, 1000) according to GOST 1770;
Pipettes 4.5-2-1 (2); 6.7-2-5 (10) according to GOST 29169;
Graduated test tubes P-1-15-0.1 according to GOST 1770;
Flat-bottomed colorimetric test tubes made of colorless glass, 120 mm high, with an internal diameter of 15 mm;
Absorption devices with porous plate No. 2;
Nitric acid according to GOST 4461, chemical grade;
Ferrous ammonium alum in accordance with current regulatory documentation, solution mass concentration 61 g/dm 3 ;
Mercury rhodanate, solution in ethyl alcohol, mass fraction 0.25%;
A solution of chlorides with an exact mass concentration of 1 mg/cm 3, prepared according to GOST 4212, is prepared by dilution.
Rectified technical ethyl alcohol according to GOST 18300, premium grade;
Distilled water according to GOST 6709.
A.4Preparing to take measurements
A4.1 Preparation of a solution of ferroammonium alum
A solution of ferroammonium alum with a mass concentration of 61 g/dm 3 is prepared as follows: 61.00 g of ferroammonium alum is transferred to a flask, 100 cm 3 of water and 310 cm 3 of nitric acid are added, dissolved and filtered through a funnel with a porous glass plate No. 4 into a volumetric flask. 2-1000-2. The solution in the flask is brought to the mark with water and mixed.
A.4.2 Air sampling
Air at a speed of 1 dm 3 /min is passed for (15 ± 0.3) minutes through two series-connected absorption devices with a porous plate containing 10 cm 3 of distilled water. Absorption solutions are quantitatively transferred into graduated test tubes, the volume is adjusted to 15 cm 3 with water and mixed.
A.4.3 Construction of a calibration graph
Place 0 in colorimetric tubes; 0.3; 0.6; 0.9; 1.2; 1.5; 2.0 cm 3 of chloride solution with an exact mass concentration of 10 μg/cm 3, which corresponds to 0; 3; 6; 9; 12; 15; 20 mcg of chlorides, bring the volume to 5 cm 3 with water, add 0.5 cm 3 of ferric ammonium alum solution and 0.4 cm 3 of thiocyanate solution and mix. After 10 minutes, measure the optical density of the calibration solutions on a photoelectrocolorimeter at a wavelength of (480 ± 5) nm and a light-absorbing layer thickness of 10 mm relative to a solution that does not contain chlorides.
Based on the data obtained, a calibration graph is constructed, plotting the masses of chlorides introduced into the calibration solutions in micrograms on the abscissa axis, and the corresponding optical densities values on the ordinate axis.
Calibration solutions prepared simultaneously with samples can be used for visual determination. Solutions are stable for 1 hour.
A.5Taking measurements
Place 1 - 5 cm 3 of the analyzed solution from the first absorption device and 5 cm 3 of the analyzed solution from the second absorption device into colorimetric test tubes, if necessary, adjust the volume with water to 5 cm 3, add 0.5 cm 3 of ferroammonium alum solution and 0.4 cm 3 solution of mercury rhodanite and proceed as described in 4.3. At the same time, prepare a control solution for the reagents. To do this, place 5 cm 3 of water and 0.5 cm 3 of ferroammonium alum solution into a colorimetric test tube and proceed as per 4.3. After 10 minutes, measure the optical densities of the analyzed solutions in relation to the control solution for reagents and, using the calibration graph, find the mass of chlorides in the analyzed solutions in mcg.
A.6Processing of measurement results
Mass concentration of hydrogen chloride X in air, mg/dm 3, calculated by the formula
P- barometric pressure during sampling, kPa;
t° - air temperature during the test, °C: (101.33 kPa = 760 mm Hg)
INTERNATIONAL STANDARD ISO 905-76
WITH hydrochloric acid for industrial use. Estimating the concentration of hydrochloric acid by measuring density
B.1Application area
This International Standard describes a method for approximately estimating the concentration of hydrochloric acid (HCl) by measuring the density of hydrochloric acid for industrial use.
B.2Principle
Determination of density at 20 °C using a hydrometer. Estimation of appropriate hydrochloric acid (HCl) concentration
B.3Equipment
Common laboratory equipment.
B.3.1 Hydrometer, graduated at 0.005 g/cm 3 , calibrated at 20 °C (see ISO (R 649)).
B.3.2 Glass test tube with a capacity of at least 500 ml, a diameter at least 25 mm greater than the diameter of the hydrometer (3.1), and a height at least 25 mm greater than the immersion level of the hydrometer.
B.4Methodology
B.4.1 Density determination
Place approximately 500 cm 3 of the test sample in a glass test tube (3.2). Adjust the temperature of the test tube contents to 20 ± 0.5 °C. Immerse the hydrometer (3.1) and, once static equilibrium is achieved, again ensure that the acid temperature is 20 ± 0.5 °C. Determine the density indicated on the hydrometer scale.
B.4.2 Estimation of hydrochloric acid (HCl) content
Take from the table the concentration corresponding to the density shown by the hydrometer.
Table B.1 - Relationship between density and concentration of aqueous solutions of hydrochloric acid
| Density at 20 °C, g/cm 3 | HCl, % , mm | Density at 20 °C, g/cm 3 | HCl, % , mm |
* Saturation value at 20 °C.
NOTE The data shown in the table is obtained by graphical interpolation of the data presented in the International Directory of Physical, Chemical and Technological Quantities, vol. 3, p. 54, rounded to the first decimal place.
B.5Expressing Results
State the density determined on the hydrometer scale, expressed in grams per cubic centimeter and the corresponding concentration of hydrochloric acid obtained from Table B.1.
TOKey words: commercial hydrochloric acid, hydrogen chloride, technical requirements, acceptance, safety measures, mass fraction, analysis result, transportation
Reagents. Mercury (II) nitrate 1-aqueous. Specifications
3.3 Marking
3.3.1 Transport marking of barrels and bottles - in accordance with GOST 14192 with the application of the handling sign “Sealed packaging”.
Marking characterizing the transport danger of the cargo - according to GOST 19433 (class 8, subclass 8.1, classification number 8172, drawing 8/6 a), UN serial number 1789.
Table 1
|
Indicator name |
Standard for the brand |
Analysis methods |
||
|
B OKP 21 2211 0200 |
||||
|
premium grade OKP |
first grade OKP |
|||
|
1 Appearance |
Transparent colorless or yellowish liquid |
Clear yellow liquid |
||
|
2 Mass fraction of hydrogen chloride, %, not less |
||||
|
3 Mass fraction of iron (Fe), %, no more |
||||
|
4 Mass fraction of residue after calcination, %, no more |
||||
|
5 Mass fraction of free chlorine, %, no more |
||||
|
6 Mass fraction of arsenic (As), %, no more |
||||
|
7 Mass fraction of mercury (Hg), %, no more |
||||
|
Notes 1 The mass fraction of mercury is normalized in the acid obtained from hydrogen and chlorine mercury electrolysis. 2 It is allowed for the food industry, by agreement with the consumer, to produce acid with a mass fraction of hydrogen chloride of no more than 26%. 3 In the acid supplied for pickling metals, the mass fraction of iron and residue after calcination is not standardized. 4 By agreement with the consumer, a mass fraction of hydrogen chloride of at least 30% is allowed in acid of both brands |
||||
3.3.2 A label made of plywood or thick cardboard, protected by an acid-resistant and moisture-proof shell, is attached to each barrel or bottle, on which data characterizing the packaged product is applied:
Name of the enterprise and (or) its trademark;
Name of the product, its brand, grade;
Designation of this standard;
Gross and net weight;
The number of the barrel or bottle and the total number of them in the batch.
3.3.3 Signs and inscriptions on tanks and containers are applied in accordance with the requirements of the “Rules for the Transportation of Dangerous Goods” (Part 2, Section 41, 1987, Moscow).
3.4 Packaging
3.4.1 Technical synthetic hydrochloric acid is poured into special rubberized tanks of the sender or recipient, rubberized containers, polyethylene barrels with a capacity of 50 and glass bottles with a capacity of 20 in accordance with the current regulatory documentation.
Glass bottles are packed in boxes type V - 1, number 3 - 2 according to GOST 18573. Packaging must comply with GOST 26319.
3.4.2 It is allowed to pour the product into tanks and containers with hydrochloric acid residue if analysis of the residue confirms that its quality meets the requirements of this standard. Otherwise, the remaining hydrochloric acid is removed and the tank or container is washed.
Barrels and bottles must be dry and clean.
3.4.3 Filling hatches of tanks, containers and barrel plugs must be sealed with rubber or polyethylene gaskets, both when sent to consumers (filled with acid) and when empty containers are returned to the supplier.
The necks of bottles, sealed with ground glass stoppers or screw caps, should be wrapped in plastic film and tied with twine.
3.4.4 The level (degree) of filling of tanks, containers, barrels and bottles is calculated taking into account the maximum use of the carrying capacity (capacity) and volumetric expansion of the product with a possible temperature difference along the route.
4 Safety requirements
4.1 Technical synthetic hydrochloric acid is a caustic liquid, chemically stable.
In air it “smoke” as a result of the release of hydrogen chloride and its attraction of air moisture with the formation of acid fog.
Metals located in the voltage series to the left of hydrogen (Al, Zn, Fe, Co, Ni, Pb, etc.) displace it from hydrochloric acid, which can lead to the formation of explosive hydrogen-air mixtures.
Safety measures include eliminating contact of hydrochloric acid with these metals through anti-corrosion coatings, nitrogen purging and testing the gas phase from equipment and pipelines for explosiveness before hot work.
4.3 Hydrochloric acid mist irritates the upper respiratory tract and mucous membranes of the eyes. In case of contact with skin, it causes burns.
4.5 Technological processes for the production and use of hydrochloric acid and the production equipment used must comply with the requirements of sanitary rules N 1042-73.
Production premises must be equipped with ventilation in accordance with GOST 12.4.021 and SNiP 2.04.05-91 and a water supply that meets the requirements of GOST 2874.
4.6 All work with hydrochloric acid must be carried out in special clothing of type K50 in accordance with GOST 12.4.103 and in safety glasses of type G in accordance with GOST 12.4.013.
All workers must be provided with industrial filtering gas masks of grade B (RPE FGP, FG-130) in accordance with GOST 12.4.121.
4.7 In the event of a spill, wash off hydrochloric acid from floor surfaces and equipment with plenty of water or an alkaline solution. Acidic wastewater must be neutralized at local treatment plants before entering the general plant sewage system.
4.8 Fire extinguishing is carried out using sprayed water and air-mechanical foam.
4.9 The substandard product is neutralized with an alkali solution. Gas emissions are captured and neutralized.
5 Acceptance
5.1 Technical synthetic hydrochloric acid must be presented for acceptance in batches.
A batch is considered to be any quantity of hydrochloric acid, homogeneous in its qualitative composition, documented in one quality document.
The quality document must contain the following data:
Name and (or) trademark of the manufacturer;
Name of the product and its brand, grade, standard designation;
Batch number, date of manufacture;
Tank number, number of containers, barrels, bottles;
Net weight;
Classification code according to GOST 19433;
The results of the analysis or confirmation of quality compliance with the requirements of this standard.
5.2 To check the quality of hydrochloric acid, acceptance and periodic tests are carried out.
5.3 The manufacturer determines the mass fraction of arsenic periodically once a quarter.
5.4 During acceptance tests at the manufacturer, samples are taken from a commercial tank intended for filling containers.
To check the quality of hydrochloric acid, samples are taken from the consumer:
From each tank and container;
From 10% of barrels, bottles, but not less than three for batches of less than 10 barrels, bottles.
5.5 If unsatisfactory analysis results are obtained for at least one of the indicators, a repeat analysis is carried out on a double sample or a newly selected sample from a tank, container, barrels, bottles.
The results of the re-analysis apply to the entire batch.
6 Methods of analysis
6.1 Point samples from the reservoir and tank are taken by slowly immersing a sampler of any design, made of acid-resistant materials, to the bottom of the reservoir or tank.
Point samples from barrels, bottles and containers are taken using a glass or polyethylene tube with a diameter of 10-15 mm with an extended end.
The pooled sample is obtained by mixing equal volumes of spot samples.
6.2 From the thoroughly mixed combined sample, take a sample for analysis with a volume of at least 1, which is placed in a dry, clean bottle with a ground-in stopper or a plastic jar with a screw-on lid. A label is placed on the bottle or plastic jar indicating:
Manufacturer and product names;
Designations of this standard, brand and grade;
Dates and places of sampling;
Batch numbers and production dates;
Last name of the person who took the sample.
6.3 General instructions for analysis
When performing the analysis, the air temperature should be .
When weighing, general-purpose laboratory scales in accordance with GOST 24104 of accuracy classes 2 and 4 with the largest weighing limits of 200 and 500 g should be used.
It is allowed to use imported utensils with an accuracy class and reagents with a quality no lower than domestic ones.
It is allowed to determine the density of hydrochloric acid according to Appendix B.
6.4 Definition of appearance
The appearance is determined visually in the transmitted light of a column of liquid poured into a cylinder 1.2-100 according to GOST 1770.
6.5 Determination of the mass fraction of hydrogen chloride
6.5.1 The determination method is based on the reaction of neutralization of hydrogen ions with sodium hydroxide:
Methyl orange is used as an indicator.
6.5.2 Equipment, reagents, solutions:
Sodium hydroxide according to GOST 4328, chemically pure, solution concentration with (NaON) = 0.1, prepared according to GOST 25794.1;
Methyl orange (indicator), solution with a mass fraction of 0.1%; an aqueous solution is prepared according to GOST 4919.1;
6.5.3 Conducting analysis
In a pre-weighed flask with a ground stopper with a capacity of 100 and containing 20 water, place 3 of the acids being analyzed and weigh again (the weighing result is recorded accurate to the fourth decimal place). The solution is quantitatively transferred into a volumetric flask with a capacity of 250, rinsed repeatedly with distilled water, poured into a volumetric flask, the volume is adjusted to the mark with water and mixed. Using a pipette, take 20 of the resulting hydrochloric acid solution into a conical flask with a capacity of 250, add 25 of water, 2-3 drops of methyl orange indicator and titrate with a solution of sodium hydroxide until the red color turns yellow.
6.5.4 Processing results
The mass fraction of hydrogen chloride X, %, is calculated using the formula
where V is the volume of sodium hydroxide solution of concentration exactly with (NaOH) = 0.1, used for titration;
The volume of the analyzed hydrochloric acid solution taken to perform the analysis is ;
m is the mass of the flask with water, g;
Mass of the flask with water and the acid being analyzed, g;
0.003646 - mass of hydrogen chloride corresponding to 1 solution of sodium hydroxide, concentration exactly with (NaOH) = 0.1, .
The result of the analysis is taken as the arithmetic mean of the results of two parallel measurements, the permissible differences between which should not exceed 0.3% with a confidence probability of P = 0.95.
The permissible differences between the results obtained in two laboratories should not exceed 0.6%. Relative total error of determination at confidence level P = 0.95.
6.6 Determination of the mass fraction of iron
6.6.1 The mass fraction of iron is determined in hydrochloric acid after diluting the sample without preliminary neutralization. Neutralization is carried out after the introduction of sulfosalicylic acid, that is, neutralization and the formation of an iron sulfosalicylate complex, colored yellow in a slightly alkaline environment (pH 8.0-11.5), occur simultaneously. The intensity of light absorption of the formed complex is measured using a photoelectrocolorimeter. Measurement range %.
6.6.2 Equipment, solutions, reagents:
Photoelectric laboratory colorimeter FEK-56M, KFK or another type, providing the specified sensitivity and accuracy;
Mechanical stopwatch of any brand;
Flasks 1.2-50, 100, 250 and 1000 according to GOST 1770;
6.6.3 Preparation for analysis
6.6.3.1 Preparation of sulfosalicylic acid solution
Transfer 10 g of sulfosalicylic acid into a 100 volumetric flask, dissolve, adjust the volume to the mark with water, and mix. Weighing results are recorded to the second decimal place.
6.6.3.2 Preparation of calibration solutions and calibration of the photoelectric colorimeter.
Calibration and determination are carried out according to GOST 10555 using the sulfosalicylic method.
30 distilled water is introduced into volumetric flasks with a capacity of 50, and 1 solution of hydrochloric acid is added with a pipette, 1.0; 2.0; 3.0; 4.0, 6.0 iron solutions of concentration 10, 2 solutions of sulfosalicylic acid and 5 ammonia solutions. After adding each reagent, the solution is stirred. The volume of the solution is adjusted to the mark with water and mixed. At the same time, prepare a control solution: add 30 water, 1 hydrochloric acid into a volumetric flask with a capacity of 50, add 2 solutions of sulfosalicylic acid and then proceed as described above.
The optical density of calibration solutions is measured every minute in cuvettes with a light-absorbing solution layer thickness of 50 mm at a wavelength of 434 nm relative to the control solution. The instrument can be calibrated using the least squares method.
Based on the results obtained, a calibration graph is constructed, plotting the mass of iron introduced into the calibration solutions in micrograms on the abscissa axis, and the corresponding values of optical densities on the ordinate axis. The calibration schedule is checked once a quarter, as well as when replacing reagents or instruments.
6.6.4 Conducting analysis
A weighed portion of the hydrochloric acid being analyzed, weighing g, is quantitatively transferred into a volumetric flask with a capacity of 250, rinsing the glass several times with water, adjusting the volume of the solution with water to the mark and mixing. Weighing results are recorded to the second decimal place.
With a pipette, for grades A and B of the highest grade, 25 are taken, and for grade B of the 1st grade - 2.5 of the prepared solution, transferred to a volumetric flask with a capacity of 50, 2 solutions of sulfosalicylic acid are added and mixed. Then add 10 ammonia solution, bring the volume to the mark with water and mix.
The control solution is prepared as described in 6.6.3.2. After a minute, the optical density is measured and, using a calibration graph, the mass of iron in the analyzed solution is found in micrograms.
6.6.5 Processing results
The mass fraction of iron,%, is calculated using the formula
where is the mass of iron in the analyzed solution, found from the calibration curve, μg;
m is the mass of a sample of hydrochloric acid taken to perform the analysis, g;
V is the volume of hydrochloric acid solution obtained after diluting the mass of hydrochloric acid;
The volume of dilute hydrochloric acid solution taken to perform the analysis is .
The result of the analysis is taken as the arithmetic mean of the results of two parallel measurements, the differences between which should not exceed 0.0005%. Determination results are rounded to the fourth decimal place.
The permissible differences between the results obtained in two laboratories should not exceed 0.0005%.
Absolute total error of determination A, where A is the result of determination with a confidence probability of P = 0.95.
6.7 Determination of the mass fraction of residue after calcination
6.7.1 The mass fraction of the residue after calcination at 600°C is measured by the gravimetric method. The detection range is from 0.005 to 0.100%.
6.7.2 Equipment, solutions and reagents:
Quartz cup type KP with a capacity of 100 according to GOST 19908, platinum or porcelain;
Muffle furnace with thermocouple, ensuring temperature maintenance;
Calcium chloride, calcined at 250-300°C;
Hourglass at 5 minutes.
6.7.3 Preparation for analysis
The cup is calcined in a muffle furnace at a temperature of min. Then the cup is placed in a desiccator with calcium chloride and left for a minute. The cooled cup is weighed. Weighing results are recorded to the fourth decimal place.
6.7.4 Conducting analysis
Using a cylinder, 85 of the hydrochloric acid to be analyzed is taken and placed in a quartz cup, 1 drop of sulfuric acid is added and evaporated in a water bath almost to dryness. The cup with the residue is heated on an electric stove until the release of sulfuric acid vapors stops. Evaporation of the analyzed acid and decomposition of sulfuric acid can be carried out under an infrared lamp.
After this, the cup with the residue is transferred to a muffle furnace, preheated to , and calcined for minutes. Transfer the cup to a desiccator, soak it for a minute and weigh it.
6.7.5 Processing results
The mass fraction of the residue after calcination, %, is calculated using the formula
where is the mass of the cup with the residue after calcination, g;
m is the mass of the empty cup, g;
V is the volume of the hydrochloric acid sample taken for analysis;
Density of hydrochloric acid, .
The result of the analysis is taken as the arithmetic mean of the results of two parallel measurements, the permissible differences between which should not exceed 0.0006%. The results of parallel determinations are rounded to 0.0001%, the result of the determination is 0.001%.
The permissible differences between the results obtained in two laboratories should not exceed 0.0008%. The absolute total error of determination is % with a confidence probability of P = 0.95.
6.8 Determination of the mass fraction of free chlorine
6.8.1 The method is based on the oxidation reaction of methyl orange with chlorine:
As a result of the oxidation of methyl orange, the color of its solutions becomes less intense. The intensity of the color depends on the order in which the solutions are mixed, so the hydrochloric acid to be analyzed is added last during stirring. The method is selective; iron (III) interferes with the determination. Measurement range %.
6.8.2 Equipment, reagents and solutions:
Photoelectric laboratory colorimeter KFK or another type, providing the specified sensitivity and accuracy;
Device for distilling arsenic according to GOST 10485;
Bromine-mercury paper, prepared according to GOST 4517.
6.9.3 Preparation for analysis
6.9.3.1 Preparation of stannous chloride solution
10 g of the reagent is dissolved in 15 hydrochloric acid (if necessary, the conical flask is heated). The solution is transferred to a volumetric flask with a ground stopper with a capacity of 100, add 0.5 g of granulated tin, and adjust the volume to the mark with water. Weighing results are recorded to the second decimal place.
6.9.3.2 Preparation of arsenic solution of concentration 0.001.
Pipette 1 arsenic solution, prepared according to GOST 4212, into a volumetric flask with a capacity of 100, bring the volume of the solution to the mark with water and mix. Using a pipette, take 10 of the resulting solution, transfer it to a 100 volumetric flask, adjust the volume to the mark with water and mix. The solution is used freshly prepared.
6.9.4 Conducting analysis
The determination is carried out according to GOST 10485. To do this, 1.7 (2 g) of the analyzed hydrochloric acid is pipetted and placed in a flask of an instrument for determining arsenic containing 30% distilled water. At the same time, prepare a reference solution: place 30 distilled water in the flask of the device and add 2 arsenic solutions with a pipette to one flask, and 4 arsenic solutions of a concentration of 0.001 to the second.
Then 7 concentrated hydrochloric acid and 0.5 tin dichloride solution are added to both flasks. Add 5 g of zinc to each flask, and bromine-mercury paper to the nozzle. Quickly close the stopper with a nozzle, carefully mix with a rotational motion and leave alone for min. After this time, the bromine-mercury papers are removed from the instruments and the color intensity of the paper is compared with the analyzed solution and the reference solution.
The product meets the established standard if the color intensity of the paper from the analyzed hydrochloric acid solution is the same as or less than the intensity of the reference solution.
6.10 Determination of mass fraction of mercury
6.10.1 Determination of the mass fraction of mercury using the “Mercury-101” analyzer.
6.10.1.1 The method is based on measuring the concentration of metallic mercury vapor in the gas phase by atomic absorption of the resonance radiation of its atoms at a wavelength of 253.7 nm.
Sample preparation involves boiling it in the presence of potassium bichromate to remove chlorine gas. Measuring range from % to %.
6.10.1.2 Equipment, reagents, solutions:
Mercury analyzer type "Mercury-101" (or other device with similar metrological characteristics);
Potassium dichromate according to GOST 4220, solution of concentration 40 (prepared as follows: 4 g of the reagent is dissolved in 100 water; stored in a flask with a ground-in stopper; weighing results are recorded accurate to the second decimal place);
The dilution solution is prepared as follows: place 50 nitric acid, 5 potassium dichromate solution into a 1000 volumetric flask and dilute to the mark with water;
Tin dichloride, a solution with a mass fraction of 10%, is prepared as follows: 10 g of the reagent is dissolved in a volumetric flask with a capacity of 100 in 25 hydrochloric acid at boiling until the reagent is completely dissolved; after cooling to water, adjust the volume to the mark; the freshly prepared solution is cleaned of mercury by blowing with air for at least 5 minutes; use on the day of preparation; weighing results are recorded accurate to the second decimal place;
Mercury (II) nitrate 1-aqueous according to GOST 4520, chemically pure, solution of concentration 0.01 (the initial solution of concentration 1 is prepared according to GOST 4212 - solution A; a solution of concentration 0.01 is prepared by appropriate dilution, for which 10 of solution A is placed into a volumetric flask with a capacity of 100 and bring the volume with the dilution solution to the mark - solution B of concentration 100; good for 3 months; 1 solution B is placed in a volumetric flask with a capacity of 100 and bring the volume with the dilution solution to the mark - solution D of concentration 1, good for 7 hours; 10 solutions G are placed in a volumetric flask with a capacity of 100 and the volume is adjusted to the mark with the dilution solution - a working solution with a concentration of 0.01, good for 7 hours);
6.10.1.3 Safety requirements when working with the “Mercury-101” device
Personnel who have studied the design of the device and have been instructed to work with electrical devices operating at a voltage of 1000 V are allowed to work. It is necessary to check the reliability of grounding before work. When repairing or replacing reagents, the device should be disconnected from the network.
6.10.1.4 Preparation for analysis
The device is calibrated according to the passport (technical description and instructions) attached to the device.
SYNTHETIC TECHNICAL HYDRATE ACID
GOST 857-95, STO 00203275-233-2009
CHEMICAL FORMULA HCl
MOLECULAR WEIGHT 36.46
|
APPEARANCE: |
|||
|
Transparent colorless or yellowish liquid. |
|||
|
SPECIFICATION: |
|||
|
INDICATOR NAME |
MEANING |
||
|
TOP GRADE |
FIRST GRADE |
||
|
Mass fraction of hydrogen chloride, %, not less |
|||
|
Mass fraction of iron (Fe), %, no more |
|||
|
Mass fraction of residue after calcination, %, no more |
|||
|
Mass fraction of free chlorine, %, no more |
|||
|
Mass fraction of arsenic (As), %, no more |
|||
|
Mass fraction of mercury (Hg),%, no more |
|||
|
Note: |
|||
|
1. The values of indicators for acid produced according to STO 00203275-233-2009 are indicated in parentheses. |
|||
APPLICATION:
In the chemical industry in the production of dyes, mineral fertilizers, coagulants and other chemical compounds; in the food industry for washing equipment, obtaining protein sausage casings, ethyl alcohol and molasses; in non-ferrous and ferrous metallurgy for pickling and preparing metal surfaces for electroplating, as well as in the medical industry.
Container, Packaging, Transportation, Storage.
According to GOST 857-95, synthetic hydrochloric acid is packaged in special rubberized railway tanks. According to STO 00203275-233-2009, synthetic hydrochloric acid is poured into special rubberized automobile tanks; special containers with a capacity of 1000 dm3, consisting of a metal lathing, a wooden pallet and a plastic container.
By rail and road transport in accordance with the rules for the transportation of dangerous goods in force for this type of transport. Store in sealed containers made of materials resistant to hydrochloric acid. The shelf life of the product is unlimited.
SPECIAL SAFETY FEATURES:
Caustic, non-flammable liquid. It “smoke” in the air. Hydrochloric acid vapors irritate the upper respiratory tract and mucous membranes of the eyes. Causes burns upon contact with skin. Dangerous product. When working with acid, it is mandatory to use personal protective equipment. KShch gloves, Gas mask, Chemical protection.
page 1
page 2
page 3
page 4
page 5
page 6
page 7
page 8
page 9
page 10
page 11
page 12
page 13
page 14
page 15
page 16
page 17
page 18
page 19
page 20
GOST 857-95
INTERSTATENUMBER STANDARD
ACIDSALT
SYNTHETIC TECHNICAL
Ttechnical conditions
INTERSTATE COUNCIL
ON STANDARDIZATION, METROLOGY AND CERTIFICATION
Minsk
Preface
1 DEVELOPED by the Kyiv Research Institute of Synthesis and Ecology (KNII "SINTECO")
INTRODUCED by the Technical Secretariat of the Interstate Council for Standardization, Metrology and Certification
2 ADOPTED by the Interstate Council for Standardization, Metrology and Certification (Protocol No. 7 of April 26, 1995)
3 Appendix B of this standard contains the full authentic text of the international standard ISO 905-76 “Hydrochloric acid for industrial use. Estimation of hydrochloric acid concentration by measuring density"
4 By Decree of the Committee of the Russian Federation on Standardization, Metrology and Certification dated February 27, 1996 No. 117, the interstate standard GOST 857-95 was put into effect directly as a state standard of the Russian Federation on January 1, 1997.
6 REPUBLICATION. November 2005
GOST 857-95
INTERSTATENUMBER STANDARD
ACIDSALT SYNTHETIC TECHNICAL
Ttechnical conditions
Synthetic hydrochloric acid for industrial use.
Specifications
Ddate of introduction 1996-07-01
1 area of use
This standard applies to technical synthetic hydrochloric acid produced by the absorption of hydrogen chloride with water, formed by the interaction of evaporated, electrolytic chlorine, chlorine liquefaction exhaust gases with hydrogen.
Technical synthetic hydrochloric acid is used in the chemical, medical, food industries, non-ferrous and ferrous metallurgy.
Formula: HCl.
Molecular mass (according to international atomic masses 1985) - 36.46.
Mandatory requirements for products aimed at ensuring their safety for life and health of the population and environmental protection are given in Table 1, paragraphs 6 and 7.
2 Normative references
3.4.2 It is allowed to pour the product into tanks and containers with hydrochloric acid residue if analysis of the residue confirms that its quality meets the requirements of this standard. Otherwise, the remaining hydrochloric acid is removed and the tank or container is washed.
Barrels and bottles must be dry and clean.
3.4.3 Filling hatches of tanks, containers and barrel plugs must be sealed with rubber or polyethylene gaskets, both when sent to consumers (filled with acid) and when empty containers are returned to the supplier.
The necks of bottles, sealed with ground glass stoppers or screw caps, should be wrapped in plastic film and tied with twine.
3.4.4 The level (degree) of filling of tanks, containers, barrels and bottles is calculated taking into account the maximum use of the carrying capacity (capacity) and volumetric expansion of the product with a possible temperature difference along the route.
4 Safety requirements
4.1 Technical synthetic hydrochloric acid is a caustic liquid, chemically stable.
In air it “smoke” as a result of the release of hydrogen chloride and its attraction of air moisture with the formation of acid fog.
Metals located in the voltage series to the left of hydrogen (Al, Zn, Fe, Co, Ni, Pb, etc.) displace it from hydrochloric acid, which can lead to the formation of explosive hydrogen-air mixtures.
Safety measures include eliminating contact of hydrochloric acid with these metals through anti-corrosion coatings, nitrogen purging and testing the gas phase from equipment and pipelines for explosiveness before hot work.
4.5 Technological processes for the production and use of hydrochloric acid and the production equipment used must comply with the requirements of sanitary regulations No. 1042-73.
Production premises must be equipped with ventilation in accordance with GOST 12.4.021 and SNiP 2.04.05-91 and a water supply that meets the requirements of GOST 2874.
4.6 All work with hydrochloric acid must be carried out in workwear type K50 in accordance with GOST 12.4.103 and in safety glasses type G in accordance with GOST 12.4.013.
All workers must be provided with industrial filter gas masks of grade B (RPE FGP, FG-130) in accordance with GOST 12.4.121.
4.7 In the event of a spill, wash off hydrochloric acid from floor surfaces and equipment with plenty of water or an alkaline solution. Acidic wastewater must be neutralized at local treatment plants before entering the general plant sewage system.
4.8 Fire extinguishing is carried out using sprayed water and air-mechanical foam.
4.9 The substandard product is neutralized with an alkali solution. Gas emissions are captured and neutralized.
5 Acceptance
5.1 Technical synthetic hydrochloric acid must be presented for acceptance in batches.
A batch is considered to be any quantity of hydrochloric acid, homogeneous in its qualitative composition, documented in one quality document.
The quality document must contain the following data:
Name and (or) trademark of the manufacturer;
Name of the product and its brand, grade, standard designation;
Batch number, date of manufacture;
Tank number, number of containers, barrels, bottles;
Net weight;
Classification code according to GOST 19433;
The results of the analysis or confirmation of quality compliance with the requirements of this standard.
5.2 To check the quality of hydrochloric acid, acceptance and periodic tests are carried out.
5.3 The manufacturer determines the mass fraction of arsenic periodically once a quarter.
5.4 During acceptance tests at the manufacturer, samples are taken from a commercial tank intended for filling containers.
To check the quality of hydrochloric acid, samples are taken from the consumer:
From each tank and container;
From 10% of barrels, bottles, but not less than three for batches of less than 10 barrels, bottles.
5.5 If unsatisfactory analysis results are obtained for at least one of the indicators, a repeat analysis is carried out on a double sample or a newly selected sample from a tank, container, barrels, bottles.
The results of the re-analysis apply to the entire batch.
6 Methods of analysis
6.1 Point samples from the reservoir and tank are taken by slowly immersing a sampler of any design, made of acid-resistant materials, to the bottom of the reservoir or tank.
Point samples from barrels, bottles and containers are taken using a glass or polyethylene tube with a diameter of 10 - 15 mm with an extended end.
The pooled sample is obtained by mixing equal volumes of spot samples.
6.2 From the thoroughly mixed combined sample, a sample for analysis with a volume of at least 1 dm 3 is taken, which is placed in a dry, clean bottle with a ground stopper or a plastic jar with a screw cap. A label is placed on the bottle or plastic jar indicating:
Manufacturer and product names;
Designations of this standard, brand and grade;
Dates and places of sampling;
Batch numbers and production dates;
Last name of the person who took the sample.
6.3 General instructions for conducting analysis
When performing the analysis, the air temperature should be (20 ± 5) °C.
When weighing, general-purpose laboratory scales in accordance with GOST 24104 of accuracy classes 2 and 4 with the largest weighing limits of 200 and 500 g should be used.
It is allowed to use imported utensils with an accuracy class and reagents with a quality no lower than domestic ones.
It is allowed to determine the density of hydrochloric acid according to Appendix B.
6.4 Defining Appearance
The appearance is determined visually in the transmitted light of a column of liquid poured into a cylinder 1.2-100 according to GOST 1770.
6.5 Determination of the mass fraction of hydrogen chloride
6.5.1 The determination method is based on the reaction of neutralization of hydrogen ions with sodium hydroxide:
H + + OH - = H 2 O. (1)
Methyl orange is used as an indicator.
6.5.2 Equipment, reagents, solutions:
Methyl orange (indicator), solution with a mass fraction of 0.1%; an aqueous solution is prepared according to GOST 4919.1;
6.5.3 Conducting analysis
In a pre-weighed flask with a ground stopper with a capacity of 100 cm 3 and containing 20 cm 3 of water, place 3 cm 3 of the acid being analyzed and weigh again (the weighing result is recorded accurate to the fourth decimal place). The solution is transferred quantitatively into a volumetric flask with a capacity of 250 cm 3, rinsed repeatedly with distilled water, poured into a volumetric flask, the volume is adjusted to the mark with water and mixed. Using a pipette, 20 cm 3 of the resulting hydrochloric acid solution is taken into a conical flask with a capacity of 250 cm 3, 25 cm 3 of water, 2-3 drops of methyl orange indicator are added and titrated with a solution of sodium hydroxide until the red color turns yellow.
6.5.4 Processing results
Mass fraction of hydrogen chloride X, %, calculated by the formula
Where V- volume of sodium hydroxide solution concentration exactly c(NaOH) = 0.1 mol/dm 3, used for titration, cm 3;
V 1 - volume of solution of the analyzed hydrochloric acid taken to perform the analysis, cm 3;
m- mass of the flask with water, g;
m 1 - mass of the flask with water and the acid being analyzed, g;
0.003646 - mass of hydrogen chloride corresponding to 1 cm 3 sodium hydroxide solution, concentration exactly c(NaOH) = 0.1 mol/dm3, g/cm3.
The result of the analysis is taken as the arithmetic mean of the results of two parallel measurements, the permissible differences between which should not exceed 0.3% with a confidence level P = 0,95.
The permissible differences between the results obtained in two laboratories should not exceed 0.6%. Relative total error of determination ±2% with confidence level P = 0,95.
6.6 Determination of the mass fraction of iron
6.6.1 The mass fraction of iron is determined in hydrochloric acid after diluting the sample without preliminary neutralization. Neutralization is carried out after the introduction of sulfosalicylic acid, that is, neutralization and the formation of iron sulfosalicylate complex 3, colored yellow in a slightly alkaline environment (pH 8.0 - 11.5), occur simultaneously. The intensity of light absorption of the formed complex is measured using a photoelectrocolorimeter. Measuring range 5 · 10 -4 - 2.0 · 10 -2%.
6.6.2 Equipment, solutions, reagents:
Photoelectric laboratory colorimeter FEK-56M, KFK or another type, providing the specified sensitivity and accuracy;
Mechanical stopwatch of any brand;
6.6.3 Preparation for analysis
6.6.3.1 Preparation of sulfosalicylic acid solution
Transfer 10 g of sulfosalicylic acid into a 100 cm3 volumetric flask, dissolve, adjust the volume to the mark with water, and mix. Weighing results are recorded to the second decimal place.
6.6.3.2 Preparation of calibration solutions and calibration of the photoelectric colorimeter.
Calibration and determination are carried out according to GOST 10555 using the sulfosalicylic method.
30 cm 3 of distilled water is introduced into volumetric flasks with a capacity of 50 cm 3, and 1 cm 3 of hydrochloric acid solution, 1.0, is added with a pipette. 2.0; 3.0; 4.0; 6.0 cm 3 of iron solution with a concentration of 10 μg/cm 3 , 2 cm 3 of sulfosalicylic acid solution and 5 cm 3 of ammonia solution. After adding each reagent, the solution is stirred. The volume of the solution is adjusted to the mark with water and mixed. At the same time, prepare a control solution: add 30 cm 3 of water, 1 cm 3 of hydrochloric acid into a volumetric flask with a capacity of 50 cm 3, add 2 cm 3 of sulfosalicylic acid solution and then proceed as described above.
The optical density of calibration solutions is measured after (10 ± 1) min in cuvettes with a light-absorbing solution layer thickness of 50 mm at a wavelength of 434 nm relative to the control solution. The instrument can be calibrated using the least squares method.
Based on the results obtained, a calibration graph is constructed, plotting the mass of iron introduced into the calibration solutions in micrograms on the abscissa axis, and the corresponding values of optical densities on the ordinate axis. The calibration schedule is checked once a quarter, as well as when replacing reagents or instruments.
6.6.4 Conducting analysis
A sample of the analyzed hydrochloric acid weighing (20 ± 1) g is transferred quantitatively into a volumetric flask with a capacity of 250 cm 3, rinsing the glass several times with water, the volume of the solution is adjusted to the mark with water and mixed. Weighing results are recorded to the second decimal place.
Using a pipette, 25 cm 3 is taken for grades A and B of the highest grade, and for grade B of the 1st grade - 2.5 cm 3 of the prepared solution, transferred to a volumetric flask with a capacity of 50 cm 3, 2 cm 3 of sulfosalicylic acid solution is added and mixed. Then add 10 cm 3 of ammonia solution, adjust the volume to the mark with water and mix.
The control solution is prepared as described in 6.6.3.2. After (10 ± 1) minutes, measure the optical density and, using the calibration graph, find the mass of iron in the analyzed solution in micrograms.
6.6.5 Processing results
Mass fraction of iron X 1,%, calculated by the formula
Where m 1 - mass of iron in the analyzed solution, found from the calibration curve, mcg;
m- mass of a sample of hydrochloric acid taken for analysis, g;
V- volume of hydrochloric acid solution obtained after diluting the mass of hydrochloric acid, cm 3;
V 1 - volume of dilute hydrochloric acid solution taken to perform the analysis, cm 3.
The result of the analysis is taken as the arithmetic mean of the results of two parallel measurements, the differences between which should not exceed 0.0005%. Determination results are rounded to the fourth decimal place.
The permissible differences between the results obtained in two laboratories should not exceed 0.0005%.
Absolute total error of determination ±0.2A, where A is the result of determination with confidence probability P = 0,95.
6.7 Determination of the mass fraction of residue after calcination
6.7.1 The mass fraction of the residue after calcination at 600 °C is measured by the gravimetric method. The detection range is from 0.005% to 0.100%.
6.7.2 Equipment, solutions and reagents:
Quartz cup type KP with a capacity of 100 cm 3 according to GOST 19908, platinum or porcelain;
Muffle furnace with a thermocouple, ensuring temperature maintenance (600 ± 10) °C;
Calcium chloride, calcined at 250 - 300 °C;
Hourglass at 5 minutes.
6.7.3 Preparation for analysis
The cup is calcined in a muffle furnace at a temperature of (600 ± 10) °C for (5 ± 1) minutes. The cup is then placed in a desiccator with calcium chloride and kept for (30 ± 5) minutes. The cooled cup is weighed. Weighing results are recorded to the fourth decimal place.
6.7.4 Conducting analysis
Using a cylinder, 85 cm 3 of the analyzed hydrochloric acid is taken and placed in a quartz cup, 1 drop of sulfuric acid is added and evaporated in a water bath almost to dryness. The cup with the residue is heated on an electric stove until the release of sulfuric acid vapors stops. Evaporation of the analyzed acid and decomposition of sulfuric acid can be carried out under an infrared lamp.
After this, the cup with the residue is transferred to a muffle furnace, preheated to (600 ± 10) °C, and calcined for (5 ± 1) minutes. Transfer the cup to a desiccator, leave for (30 ± 5) minutes and weigh.
6.7.5 Processing results
Mass fraction of residue after calcination X 2,%, calculated by the formula
Where m 1 - mass of the cup with the residue after calcination, g;
m- mass of an empty cup, g;
V- volume of hydrochloric acid sample taken for analysis, cm 3;
The result of the analysis is taken as the arithmetic mean of the results of two parallel measurements, the permissible differences between which should not exceed 0.0006%. The results of parallel determinations are rounded to 0.0001%, the result of the determination is 0.001%.
The permissible differences between the results obtained in two laboratories should not exceed 0.0008%. Absolute total error of determination ±0.0005% with confidence probability P = 0,95.
6.8 Determination of the mass fraction of free chlorine
6.8.1 The method is based on the oxidation reaction of methyl orange with chlorine:
As a result of the oxidation of methyl orange, the color of its solutions becomes less intense. The intensity of the color depends on the order in which the solutions are mixed, so the hydrochloric acid to be analyzed is added last during stirring. The method is selective; iron (III) interferes with the determination. Measuring range 5 · 10 -4 - 8 · 10 -3%.
6.8.2 Equipment, reagents and solutions:
Photoelectric laboratory colorimeter KFK or another type, providing the specified sensitivity and accuracy;
Device for distilling arsenic according to GOST 10485;
Bromine-mercury paper, prepared according to GOST 4517.
6.9.3 Preparation for analysis
6.9.3.1 Preparation of stannous chloride solution
10 g of the reagent is dissolved in 15 cm 3 of hydrochloric acid (if necessary, the conical flask is heated). The solution is transferred to a volumetric flask with a ground stopper with a capacity of 100 cm 3, 0.5 g of granulated tin is added, and the volume is adjusted to the mark with water. Weighing results are recorded to the second decimal place.
6.9.3.2 Preparation of arsenic solution with a concentration of 0.001 mg/cm3
Pipette 1 cm 3 of arsenic solution prepared according to GOST 4212 into a volumetric flask with a capacity of 100 cm 3, bring the volume of the solution to the mark with water and mix. Using a pipette, 10 cm 3 of the resulting solution is taken, transferred to a volumetric flask with a capacity of 100 cm 3, the volume is adjusted to the mark with water and mixed. The solution is used freshly prepared.
6.9.4 Conducting analysis
Potassium dichromate according to GOST 4220, solution concentration 40 g/dm 3 (prepared as follows: 4 g of the reagent is dissolved in 100 cm 3 of water; stored in a flask with a ground stopper; weighing results are recorded accurate to the second decimal place);
The dilution solution is prepared as follows: place 50 cm 3 of nitric acid, 5 cm 3 of potassium dichromate solution into a volumetric flask with a capacity of 1000 cm 3 and add water to the mark;
Tin dichloride, a solution with a mass fraction of 10%, is prepared as follows: 10 g of the reagent is dissolved in a volumetric flask with a capacity of 100 cm 3 in 25 cm 3 of hydrochloric acid at boiling until the reagent is completely dissolved; after cooling to (20 ± 5) °C, the volume is adjusted to the mark with water; the freshly prepared solution is cleaned of mercury by blowing with air for at least 5 minutes; use on the day of preparation; weighing results are recorded accurate to the second decimal place;
Mercury (II) nitrate 1-aqueous, chemically pure, solution of concentration 0.01 μg/cm 3 (the initial solution of concentration 1 mg/cm 3 is prepared according to GOST 4212 - solution A; a solution of concentration 0.01 μg is prepared by appropriate dilution /cm 3 , for which 10 cm 3 of solution A is placed in a volumetric flask with a capacity of 100 cm 3 and the volume is adjusted to the mark with the dilution solution - solution B with a concentration of 100 μg/cm 3 ; good for 3 months; 1 cm 3 of solution B is placed in a volumetric flask with a capacity of 100 cm 3 and bring the volume with the dilution solution to the mark - solution G with a concentration of 1 μg/cm 3, good for 7 hours; 10 cm 3 of solution G is placed in a volumetric flask with a capacity of 100 cm 3 and bring the volume with the dilution solution to the mark - working solution concentration 0.01 μg/cm 3, good for 7 hours);
6.10.1.3 Safety requirements when working with the “Mercury-101” device
Personnel who have studied the design of the device and have been instructed to work with electrical devices operating at a voltage of 1000 V are allowed to work. It is necessary to check the reliability of grounding before work. When repairing or replacing reagents, the device should be disconnected from the network.
6.10.1.4 Preparation for analysis
The device is calibrated according to the passport (technical description and instructions) attached to the device.
6.10.1.5 Sample preparation
10 g of hydrochloric acid to be analyzed is placed into two pre-weighed conical flasks containing (20 ± 1) cm 3 of distilled water. Weighing results are recorded to the second decimal place. Then up to 1 cm 3 of potassium bichromate solution is added to the flasks and the samples are boiled for 5 minutes, provided that the yellow color of potassium bichromate is preserved. Otherwise, add a solution of potassium dichromate in portions of 0.5 cm 3. After cooling, the solution is quantitatively transferred into a volumetric flask with a capacity of 100 cm 3 and adjusted to the mark with water (solution D).
At the same time, under the same conditions, a control experiment is carried out, for which 20 cm 3 of water and the same amount of potassium dichromate that was used in preparing the sample are introduced into the same conical flask. Boil for 5 minutes. After cooling, the solution is transferred to a 100 cm 3 volumetric flask (solution E).
2 cm 3 of solution D is placed in a volumetric flask with a capacity of 100 cm 3 and the volume is adjusted to the mark with a dilution solution (solution D 1). Solution E is also diluted and solution E 1 is obtained.
6.10.1.6 Conducting analysis.
Solutions D 1 and E 1 are placed sequentially, starting with the control one, into the reactor of the analyzer and the measurement is carried out according to the instructions for the device.
The result of the analysis is taken as the arithmetic mean of the analyzer readings for two parallel samples (a), the discrepancy between which does not exceed ±(10 + 0.05), where is the arithmetic mean of the analyzer readings for two parallel samples.
6.10.1.7 Processing results
Mass fraction of mercury X 4,%, calculated by the formula
where is the arithmetic mean of the analyzer readings when measuring two parallel samples;
b- analyzer readings when measuring the control solution;
1/1000 - analyzer division value, µg;
m- mass of the analyzed acid sample, g (10 g).
Measurement results are rounded to 1 · 10 -5%.
Relative total measurement error ±10% with confidence level P = 0,95.
6.10.2 Determination of the mass fraction of mercury with dithizone
6.10.2.1 Equipment, solutions and reagents:
Dithizone (diphenylthiocarbazone) according to current regulatory documentation, analytical grade. (a solution of dithizone in chloroform is prepared as follows: 0.2 g of dithizone is dissolved in 50 cm 3 of chloroform, transferred to a separating funnel with a capacity of 250 cm 3, add 100 cm 3 of ammonia solution (1:10) and shake; the ammonia solution is separated and transferred to another separating funnel; the operation is repeated three times; then the ammonia solution is acidified with sulfuric acid to pH 3 - 4 and dithizone is extracted three times with chloroform in portions of 20 cm 3; the chloroform extract is washed three times and diluted to 100 cm 3 with chloroform (solution A); save the solution dithizone under a layer of sulfuric acid solution in a dark, cool place; before use, solution A is diluted with chloroform so that the optical density of the solution, measured on a FEK-56 photoelectrocolorimeter or another brand device, at a wavelength of 580 - 587 nm (light filter 8 in a cuvette with a thickness light-absorbing layer of solution 0.5 cm) would be 0.75 (solution B);
A sample solution of mercury is prepared according to GOST 4212 or as follows: 0.1079 g of mercury oxide is dissolved by gently heating in 2 - 3 cm 3 of concentrated nitric acid and brought to 100 cm 3 with water; 1 cm 3 of the resulting solution contains 1 mg of mercury; by dilution prepare a solution containing 0.010 mg of mercury per 1 cm3; weighing results are recorded accurate to the fourth decimal place:
Universal indicator paper;
Photoelectric colorimeter FEK-56 or a similar device with a specified accuracy and sensitivity;
6.10.2.2 Construction of a calibration graph
Into five separating funnels with a capacity of 250 cm 3 add 50 cm 3 of water, 1, 2, 3, 4 and 5 cm 3 of a diluted standard solution of mercury, which corresponds to 0.010; 0.020; 0.030; 0.040 and 0.050 mg of mercury, 5 cm 3 of Trilon B solution, 10 cm 3 of buffer solution, stirred for 1 minute, added 5 cm 3 of chloroform, stirred again for 1 minute and after settling, the chloroform was discarded. Then add 10 cm 3 of solution B (dithizone) and shake for 2 minutes. In parallel, a control solution containing all reagents except mercury is prepared under the same conditions.
After phase separation, the chloroform layer is separated and the optical density is measured on a photoelectrocolorimeter in a cuvette with a light-absorbing solution layer thickness of 0.5 cm with a light filter of 8. The reference solution is chloroform.
The calibration graph is plotted in the coordinates “optical density - mercury concentration, mg”.
6.10.2.3 Conducting analysis
5 cm 3 of the acid being analyzed is placed in a glass with a capacity of 100 cm 3 and water is added to 30 cm 3. The contents of the glass, after cooling, are slowly neutralized with an ammonia solution to pH 4 on indicator paper, water is added to 50 cm 3, 5 cm 3 of Trilon B solution, 10 cm 3 of a buffer solution, 1 - 3 cm 3 of hydroxylamine solution. After 10 minutes, the solution is transferred to a separating funnel with a capacity of 250 cm 3, 5 cm 3 of chloroform is added, mixed, and after settling, the chloroform layer is discarded.
To check the purity of the reagents, a control experiment is carried out, for which 50 cm 3 of water is placed in a separating funnel with a capacity of 250 cm 3, 5 cm 3 of Trilon B, 10 cm 3 of a buffer solution, and 1 - 3 cm 3 of hydroxylamine solution are introduced. After 10 minutes, 5 cm 3 of chloroform is added, stirred for 1 minute, and after settling, the chloroform layer is discarded. Extraction and determination of mercury are carried out as described in 6.10.2.2.
6.10.2.4 Processing results
Mass fraction X 6,%, calculated by the formula
Where m 1 - mass of mercury in the analyzed sample, found from the calibration curve, mg;
m 2 - mass of mercury found in the control experiment, mg;
V- volume of hydrochloric acid taken for analysis, cm 3;
ρ - density of hydrochloric acid, g/cm3.
The result of the analysis is taken as the arithmetic mean of the results of two parallel measurements, the permissible differences between which should not exceed 3 · 10 -5%.
In case of disagreement in assessing the quality of products, the mass fraction of mercury is determined using a chemical method.
7 Transportation and storage
7.1 Technical synthetic hydrochloric acid is transported in accordance with the rules for the transportation of dangerous goods:
In bulk in railway tanks (“Rules for the transportation of dangerous goods No. 340”, part 2, section 41);
Packed in barrels and bottles in boxes - by rail in covered wagons by wagonload (“Rules for the transportation of dangerous goods No. 340”, part 2, section 42);
7.3 Technical synthetic hydrochloric acid is stored in sealed containers of the manufacturer and consumer, made of materials resistant to hydrochloric acid.
The shelf life of the product is unlimited.
APPENDIX A
METHODOLOGY
measuring the mass concentration of hydrogen chloride in the air of industrial premises
A.1Purpose and scope
This technique is intended to measure the mass concentration of hydrogen chloride in the air of industrial premises.
The technique was carried out in accordance with current regulatory documentation.
Measurement range - (0.6 - 20) mg/m3.
Duration of analysis - 30 minutes.
A.2Method of measurement
To measure the mass concentration of hydrogen chloride in the air, a photocolorimetric analysis method is used, based on the interaction of chloride with mercury thiocyanate and the formation of a colored iron complex with thiocyanate.
;Flat-bottomed colorimetric test tubes made of colorless glass, 120 mm high, with an internal diameter of 15 mm;
Absorption devices with porous plate No. 2;
Ferrous ammonium alum in accordance with current regulatory documentation, solution mass concentration 61 g/dm 3 ;
Mercury rhodanate, solution in ethyl alcohol, mass fraction 0.25%;
A solution of chlorides with an exact mass concentration of 1 mg/cm 3, prepared in accordance with GOST 4212, a solution of chlorides with an exact mass concentration of 10 μg/cm 3 is prepared by dilution;
Rectified technical ethyl alcohol according to GOST 18300, premium grade;
A.4Preparing to take measurements
A4.1 Preparation of a solution of ferroammonium alum
A solution of ferroammonium alum with a mass concentration of 61 g/dm 3 is prepared as follows: 61.00 g of ferroammonium alum is transferred to a flask, 100 cm 3 of water and 310 cm 3 of nitric acid are added, dissolved and filtered through a funnel with a porous glass plate No. 4 into a volumetric flask. 2-1000-2. The solution in the flask is brought to the mark with water and mixed.
A.4.2 Air sampling
Air at a speed of 1 dm 3 /min is passed for (15 ± 0.3) minutes through two series-connected absorption devices with a porous plate containing 10 cm 3 of distilled water. Absorption solutions are quantitatively transferred into graduated test tubes, the volume is adjusted to 15 cm 3 with water and mixed.
A.4.3 Construction of a calibration graph
Place 0 in colorimetric tubes; 0.3; 0.6; 0.9; 1.2; 1.5; 2.0 cm 3 of chloride solution with an exact mass concentration of 10 μg/cm 3, which corresponds to 0; 3; 6; 9; 12; 15; 20 mcg of chlorides, bring the volume to 5 cm 3 with water, add 0.5 cm 3 of ferric ammonium alum solution and 0.4 cm 3 of thiocyanate solution and mix. After 10 minutes, measure the optical density of the calibration solutions on a photoelectrocolorimeter at a wavelength of (480 ± 5) nm and a light-absorbing layer thickness of 10 mm relative to a solution that does not contain chlorides.
Based on the data obtained, a calibration graph is constructed, plotting the masses of chlorides introduced into the calibration solutions in micrograms on the abscissa axis, and the corresponding optical densities values on the ordinate axis.
Calibration solutions prepared simultaneously with samples can be used for visual determination. Solutions are stable for 1 hour.
A.5Taking measurements
Place 1 - 5 cm 3 of the analyzed solution from the first absorption device and 5 cm 3 of the analyzed solution from the second absorption device into colorimetric test tubes, if necessary, adjust the volume with water to 5 cm 3, add 0.5 cm 3 of ferroammonium alum solution and 0.4 cm 3 solution of mercury rhodanite and proceed as described in 4.3. At the same time, prepare a control solution for the reagents. To do this, place 5 cm 3 of water and 0.5 cm 3 of ferroammonium alum solution into a colorimetric test tube and proceed as per 4.3. After 10 minutes, measure the optical densities of the analyzed solutions in relation to the control solution for reagents and, using the calibration graph, find the mass of chlorides in the analyzed solutions in mcg.
A.6Processing of measurement results
Mass concentration of hydrogen chloride X in air, mg/dm 3, calculated by the formula
or according to this formula
Where a 1 and a 2 - masses of chlorides in the analyzed solutions in the first and second absorption devices, respectively, found according to the calibration curve, μg;
1.028 - conversion factor to hydrogen chloride;
V 1 - volume of the analyzed solution of the first absorption device, taken for analysis, cm 3;
V 0 - volume of air in dm 3, selected for analysis and reduced to standard conditions according to the formula
Where V t- volume of air selected for analysis, dm 3 ;
P- barometric pressure during sampling, kPa;
t° - air temperature during the test, °C: (101.33 kPa = 760 mm Hg)
APPENDIX B
INTERNATIONAL STANDARD ISO 905-76
WITH hydrochloric acid for industrial use. Estimating the concentration of hydrochloric acid by measuring density
B.1Application area
This International Standard describes a method for approximately estimating the concentration of hydrochloric acid (HCl) by measuring the density of hydrochloric acid for industrial use.
B.2Principle
Determination of density at 20 °C using a hydrometer. Estimation of appropriate hydrochloric acid (HCl) concentration
B.3Equipment
Common laboratory equipment.
B.3.1 Hydrometer, graduated at 0.005 g/cm 3 , calibrated at 20 °C (see ISO (R 649)).
B.3.2 Glass test tube with a capacity of at least 500 ml, a diameter at least 25 mm greater than the diameter of the hydrometer (3.1), and a height at least 25 mm greater than the immersion level of the hydrometer.
B.4Methodology
B.4.1 Density determination
Place approximately 500 cm 3 of the test sample in a glass test tube (3.2). Adjust the temperature of the test tube contents to 20 ± 0.5 °C. Immerse the hydrometer (3.1) and, once static equilibrium is achieved, again ensure that the acid temperature is 20 ± 0.5 °C. Determine the density indicated on the hydrometer scale.
B.4.2 Estimation of hydrochloric acid (HCl) content
Take from the table the concentration corresponding to the density shown by the hydrometer.
Table B.1 - Relationship between density and concentration of aqueous solutions of hydrochloric acid
|
Density at 20 °C, g/cm 3 |
HCl, % , mm |
Density at 20 °C, g/cm 3 |
HCl, % , mm |
* Saturation value at 20 °C.
NOTE The data shown in the table is obtained by graphical interpolation of the data presented in the International Directory of Physical, Chemical and Technological Quantities, vol. 3, p. 54, rounded to the first decimal place.
B.5Expressing Results
State the density determined on the hydrometer scale, expressed in grams per cubic centimeter and the corresponding concentration of hydrochloric acid obtained from Table B.1.
TOKey words: commercial hydrochloric acid, hydrogen chloride, technical requirements, acceptance, safety measures, mass fraction, analysis result, transportation
