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GB/T 23940-2021 English PDF (GBT23940-2021)

GB/T 23940-2021 English PDF (GBT23940-2021)

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GB/T 23940-2021: Analytical methods of persulfate products for industrial use

This document specifies the general requirements for the analysis methods of persulfate products for industrial use, the analysis methods of persulfate content and active oxygen content, pH, iron content, chloride content, moisture, manganese content, heavy metal content, ammonium salt content, and ignition residue content. This document applies to persulfate products for industrial use, including sodium persulfate for industrial use, potassium persulfate for industrial use, ammonium persulfate for industrial use, etc.
GB/T 23940-2021
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 71.060.01
CCS G 10
Replacing GB/T 23940-2009
Analytical methods of persulfate products for industrial use
ISSUED ON: AUGUST 20, 2021
IMPLEMENTED ON: MARCH 01, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of the PEOPLE Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 5
4 General provisions ... 5
5 Determination of persulfate content and active oxygen content ... 5
6 Determination of pH ... 6
7 Determination of iron content ... 7
8 Determination of chloride content ... 8
9 Determination of moisture ... 9
10 Determination of manganese content ... 10
11 Determination of heavy metal content ... 11
12 Determination of ammonium salt content ... 12
13 Determination of ignition residue content ... 13
Analytical methods of persulfate products for industrial use
Warming: Some of the reagents used in this document are corrosive, and careful handling is required! If splashed on the skin or eyes, rinse with water immediately; if it is serious, seek medical attention immediately. Personnel using this document shall have practical experience in formal laboratory work. This document does not address all possible security issues. It is the responsibility of the user to take appropriate safety and health measures and to ensure compliance with the conditions which are set by the relevant national regulations.
1 Scope
This document specifies the general requirements for the analysis methods of persulfate products for industrial use, the analysis methods of persulfate content and active oxygen content, pH, iron content, chloride content, moisture, manganese content, heavy metal content, ammonium salt content, and ignition residue content.
This document applies to persulfate products for industrial use, including sodium persulfate for industrial use, potassium persulfate for industrial use, ammonium persulfate for industrial use, etc.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the version corresponding to that date is applicable to this document; for undated references, the latest version (including all amendments) is applicable to this document. GB/T 3049-2006, Chemical products for industrial use - General method for determination of iron content - 1,10-Phenanthroline spectrophotometric method GB/T 6682-2008, Water for analytical laboratory use - Specification and test methods
GB/T 23769-2009, Inorganic chemical products - General method for the
determination of pH values
HG/T 3696.1, Inorganic chemicals for industrial use - Preparations of standard and reagent solutions for chemical analysis - Part 1: Preparations of standard volumetric solutions
HG/T 3696.2, Inorganic chemicals for industrial use - Preparations of standard and reagent solutions for chemical analysis - Part 2: Preparations of standard solutions for impurity
HG/T 3696.3, Inorganic chemicals for industrial use - Preparations of standard and reagent solutions for chemical analysis - Part 3: Preparations of reagent solutions 3 Terms and definitions
No terms and definitions need to be defined in this document.
4 General provisions
The reagents and water used in this document refer to analytical reagents and grade-3 water specified in GB/T 6682-2008, unless other requirements are specified. The standard titration solutions, impurity standard solutions, preparations and products used in the test shall be prepared according to the regulations of HG/T 3696.1, HG/T 3696.2 and HG/T 3696.3 unless other requirements are specified.
5 Determination of persulfate content and active oxygen
content
5.1 Principle
Potassium iodide reacts with persulfate to generate free iodine. In a weakly acidic solution, use starch as an indicator and use sodium thiosulfate standard titration solution for titration.
5.2 Reagents or materials
5.2.1 Potassium iodide.
5.2.2 Glacial acetic acid solution: 1+2.
5.2.3 Sodium thiosulfate standard titration solution: c(Na2S2O3) ??? 0.1 mol/L. 5.2.4 Starch indicator solution: 10 g/L (the use period is about two weeks). 5.3 Test steps
Weigh about 0.3 g of the sample, accurate to 0.000 2 g; place it in a 250 mL iodine flask. Add 30 mL of water to dissolve it; add 4 g of potassium iodide; cover the bottle; shake well; seal it with water. Place in the dark for 30 min; add 2 mL of glacial acetic acid solution and 25 mL of water; use sodium thiosulfate standard titration solution for Carbon dioxide-free water.
6.2 Instruments and equipment
Acidity meter: accuracy 0.02 pH unit. Equipped with glass electrodes, saturated calomel electrodes or combination electrodes.
6.3 Test steps
Weigh 5.00 g ?? 0.01 g of the sample; place it in a 250 mL beaker; add 100 mL of carbon dioxide-free water at about 25 ??C; after the sample is completely dissolved, follow the steps specified in 8.3 of GB/T 23769-2009.
7 Determination of iron content
7.1 Principle
Same as Chapter 3 of GB/T 3049-2006.
7.2 Reagents or materials
Same as Chapter 4 of GB/T 3049-2006.
7.3 Instruments and equipment
7.3.1 Porcelain evaporating dish: volume 50 mL.
7.3.2 Constant temperature water bath.
7.3.3 Spectrophotometer: equipped with a 4 cm cuvette.
7.4 Test steps
7.4.1 Drawing of the standard curve
According to the steps specified in 6.3 of GB/T 3049-2006, use a 4 cm cuvette to draw a standard curve with an iron content of 10 ??g ~ 100 ??g.
7.4.2 Preparation of test solution A
Weigh an appropriate amount of sample (10 g for sodium persulfate and potassium persulfate, and 20 g for ammonium persulfate), accurate to 0.01 g; place in a porcelain evaporating dish; add a small amount of water to moisten; cover with a watch glass; decompose by heating on a constant temperature water bath and evaporate to dryness. Slowly heat on the electric furnace until a large amount of white smoke begins to escape; cool down. Use water to dissolve the residue; transfer it all to a 100 mL volumetric flask; use water to dilute to the mark; shake well. This solution is the test solution A, which is used for the determination of iron content and heavy metal content. 8.2.4 Chloride standard solution: 1 mL of solution contains 0.010 mg of chlorine (Cl). Use a pipette to pipette 1 mL of chloride standard solution prepared according to the requirements of HG/T 3696.2; place it in a 100 mL volumetric flask; use water to dilute to the mark; shake well. Formulate the solution when needed.
8.3 Test steps
Weigh an appropriate amount of the sample (0.50 g ?? 0.01 g for sodium persulfate and potassium persulfate, and 2.00 g ?? 0.01 g for ammonium persulfate); place it in a 50 mL beaker; add an appropriate amount of water to dissolve it. Transfer all the solution to a 50 mL colorimetric tube; add 1 mL of 95% ethanol, 1 mL of nitric acid solution and 2 mL of silver nitrate solution; use water to dilute to the mark; shake gently; let it stand for 10 min; compare it with the standard turbidimetric solution under a black background.
The standard turbidimetric solution is based on the chloride content specified in the product standard. Use a pipette to pipette the specified amount of chloride standard solution; treat it in the same way as the sample at the same time.
9 Determination of moisture
9.1 Instruments and equipment
9.1.1 Weighing bottle: ??50 mm ?? 30 mm.
9.1.2 Electrothermal constant-temperature drying oven: the temperature can be controlled at 100 ??C ?? 2 ??C.
9.1.3 Vacuum pump.
9.1.4 Vacuum drying box: the temperature can be controlled within the temperature range specified in Table 1.
9.2 Test steps
Use a weighing bottle that has been dried to a constant mass according to the drying conditions specified in Table 1, to weigh about 5 g of the sample, accurate to 0.000 2 g. Shake the weighing bottle slowly to make the thickness of the sample uniform; place it in a drying box (if a vacuum drying box is used for drying, use a vacuum pump to draw to vacuum and keep the vacuum degree); place it for the drying time specified in Table 1; take it out; place it in a desiccator; cool to room temperature; weigh. 10.2.3 Manganese standard solution: 1 mL of solution contains 0.010 mg of manganese (Mn). Pipette 1 mL of the manganese standard solution that is prepared according to HG/T 3696.2; place it in a 100 mL volumetric flask; use water to dilute to the mark; shake well. Formulate the solution when needed.
10.3 Test steps
Weigh an appropriate amount of sample (10.50 g ?? 0.01 g for sodium persulfate and ammonium persulfate, and 1.50 g ?? 0.01 g for potassium persulfate); place it in a 50 mL beaker; add an appropriate amount of water to dissolve it, and transfer it all to a 50 mL colorimetric tube; add 0.5 mL of phosphoric acid and 1 mL of silver nitrate solution; use water to dilute to the mark; shake well. Let it stand for 5 min and compare it with the standard colorimetric solution.
Measure the standard colorimetric solution by weighing 0.50 g ?? 0.01 g of the sample and the manganese content specified in the product standard; use a pipette to pipette a specified amount of manganese standard solution; treat it in the same way as the sample. 11 Determination of heavy metal content
11.1 Principle
When the sample is in an acidic medium with a pH of 3 ~ 4, add saturated hydrogen sulfide aqueous solution to convert heavy metals into sulfides; compare the dark color with the standard colorimetric solution by visual colorimetry.
11.2 Reagents or materials
11.2.1 Ammonia solution: 1+9.
11.2.2 Glacial acetic acid solution: 1+2.
11.2.3 Saturated hydrogen sulfide water: prepare this solution before use. 11.2.4 Sodium sulfide solution.
11.2.5 Lead standard solution: 1 mL of solution contains 0.010 mg of lead (Pb). Pipette 1 mL of the lead standard solution that is prepared according to HG/T 3696.2; place it in a 100 mL volumetric flask; use water to dilute to the mark; shake well. Formulate the solution when needed.
11.2.6 Phenolphthalein indicator solution: 10 g/L.
11.3 Test steps
Pipette 20 mL of the test solution A (see 7.4.2); put it into a 50 mL colorimetric tube; add 1 ~ 2 drop(s) of phenolphthalein indicator solution; use ammonia solution to neutralize it until the solution is reddish (pH ??? 7); add water to about 25 mL; add 0.5 mL of glacial acetic acid solution, 10 mL of saturated hydrogen sulfide water or 2 drops of sodium sulfide solution; use water to dilute to the mark; shake well. Let it stand for 10 min and compare it with the standard colorimetric solution.
Prepare the standard colorimetric solution by pipetting 10 mL of test solution A (see 7.4.2) and the heavy metal content as specified in the product standard; pipette the specified amount of lead standard solution; prepare it in the same way as the sample at the same time.
12 Determination of ammonium salt content
12.1 Principle
In alkaline solution, Nessler?€?s reagent reacts with ammonia to generate yellow to brown-red insoluble compounds; compare it with standard colorimetric solutions by visual colorimetry.
12.2 Reagents or materials
12.2.1 Sodium hydroxide solution: 100 g/L.
12.2.2 Nessler?€?s reagent.
12.2.3 Ammonium standard solution: 1 mL of solution contains 0.010 mg of ammonium (NH4). Pipette 1 mL of the ammonium standard solution that is prepared according to HG/T 3696.2; place it in a 100 mL volumetric flask; use water to dilute to the mark; shake well. Formulate the solution when needed.
12.3 Test steps
Weigh 1.00 g ?? 0.01 g of the sample; place it in a 50 mL beaker; add an appropriate amount of water to dissolve it; transfer all the solution to a 100 mL volumetric flask; use water to dilute to the mark; shake well.
Use a pipette to pipette 1.00 mL of the above test solution; put it in a 50 mL colorimetric tube; add water to about 25 mL; add 2 mL of sodium hydroxide solution and 2 mL of Nessler's reagent; use water to dilute to the mark; shake well; compare it with the standard colorimetric solution.
The standard turbidimetric solution is based on the ammonium salt content specified in the product standard. Pipette the specified amount of ammonium standard solution; treat it in the same way as the sample at the same time.

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