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HG/T2785—1996
This standard is a revision of ZB/TG12004—1987 "Ammonium Bisulfite for Industrial Use". Compared with the previous version, this standard changes the unit of g/L for expressing the content of ammonium bisulfite, ammonium sulfite and ammonium thiosulfate to mass percentage. This standard will replace ZB/TG12004—1987 from the date of implementation. This standard is proposed by the Technical Supervision Department of the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the sulfur and sulfuric acid standardization technical unit of the Ministry of Chemical Industry. The responsible drafting unit of this standard: Nanjing Chemical Industry (Group) Corporation Research Institute. The main drafters of this standard: Zhang Ruai, Zhao Yifang, Li Xiuling. This standard was first issued in 1987.
Chemical Industry Standard of the People's Republic of China
Industrial Ammonium Bisulfite
HG/T 2785—1996
Replaces ZB/TG12004—1987
This standard specifies the requirements, test methods, and marking, labeling, and packaging of industrial ammonium bisulfite. This standard applies to ammonium bisulfite products obtained by recovering sulfur dioxide from sulfuric acid tail gas using ammonium bicarbonate or other ammonia sources as raw materials. Molecular formula: NH, HSO:
Relative molecular mass: 99.11 (according to the 1991 international relative atomic mass) 2 Reference standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is released, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest version of the following standards. GB/T601--1988 Preparation of standard solutions for titration analysis (volumetric analysis) of chemical reagents GB/T603-1988 Preparation of preparations and products used in test methods for chemical reagents (neqISO6353-1:1982) GB/T1250-1989 Methods for expressing and determining limit values GB/T6678-1986 General rules for sampling of chemical products GB/T6680--1986 General rules for sampling of liquid chemical products GB/T6682-1992 Specifications and test methods for water used in analytical laboratories (eqvISO3696:1987) 3 Requirements
Qualified ammonium bisulfite products shall comply with the requirements of Table 1. Table 1
Total of ammonium bisulfite and ammonium sulfite/%
Ammonium thiosulfate/%
Ratio of ammonium bisulfite/ammonium sulfite
4 Sampling
Light yellow liquid
4.1 Liquid ammonium bisulfite in railway tank cars, automobile tank cars, storage tanks or plastic bags, with one car or one tank or one bag as a batch. 4.2 Sampling shall be carried out in accordance with the provisions of Chapter 2 of GB/T6680. The sampling volume shall be not less than 500mL. Divide the samples into two clean, dry wide-mouth bottles with stoppers and seal them. Label the bottles with the manufacturer name, product name, category, grade, batch number, sampling date and name of the sampler. One bottle is for inspection and the other is kept for future reference. 5 Test Methods
The reagents and water used in this standard, unless otherwise specified, are analytically pure reagents and Grade III water as specified in GB/T6682 (approved by the Ministry of Chemical Industry of the People's Republic of China on January 23, 1996 and implemented on January 1, 1997).
HG/T 2785—1996
The standard solutions, preparations and products required in the test, unless otherwise specified, are prepared in accordance with the provisions of GB/T601 and GB/T603.
The rounding value comparison method specified in (GB/T1250) is used to determine whether the test results meet the standards. 5.1 Appearance
Determine by the surrounding measurement method.
5.2 Determination of ammonium bisulfite content
5.2.1 Principle
The ammonium bisulfite in the sample is oxidized and oxidized to form ammonium bisulfate, and then methyl red-indigo mixed solution is used as an indicator and titrated with sodium hydroxide standard titration solution until the yellow-green end point. The content of ammonium bisulfite is calculated from the consumption of sodium hydroxide standard titration solution. Reaction formula:
NH,HSO +H,O2 →NH,HSO +H2O
5.2.2 Reagents and materials
2NH.HSO4+2NaOH -→(NH,),SO,Na SO.+2H20 Sodium hydroxide standard titration solution: c(NaOH)=0.1000mol/L. 5.2.2.1
5.2.2.2 Methyl red ethanol solution: 1g/L. 5:2.2.3 Indigo (chemically pure) ethanol solution: 1g/L. 5.2.2.4 Methyl red-indigo mixed indicator: prepared by adding 1 part of methyl red ethanol solution and 2 parts of indigo ethanol solution. 5.2.2.5 Hydrogen peroxide solution: 3%.
5.2.2.6 Neutral hydrogen peroxide solution:
Use methyl red-indigo mixed indicator as the indicator and use sodium hydroxide standard titration solution to neutralize the 3% hydrogen peroxide solution until it changes from red to yellow-green.
5.2.3 Determination
5.2.3.1 Test solution Preparation
Weigh about 5g~6.5g of sample (accurate to 0.0002g), place it in a 250mL volumetric flask containing 150mL of water, dilute with water to the mark, shake well, and use it as the test solution for determining the content of ammonium sulfite, ammonium bisulfite and ammonium thiosulfate. 5.2.3.2 Determination
Accurately pipette 5mL10mL (depending on the content) of the test solution, inject it into a 250ml conical flask containing 15ml of neutral hydrogen peroxide solution and 30ml of water, and shake well. If 5 drops of methyl red-indigo mixed indicator are added, the solution will turn red. Titrate with sodium hydroxide standard titration solution until the solution turns yellow-green as the end point. 5.2.4 Expression of analytical results
The ammonium bisulfite content (X) expressed as mass percentage is calculated according to formula (1): X = ic×0. 09911 × 100
m×250
Wherein: V
The volume of sodium hydroxide standard titration solution consumed during titration, mL; V.-The volume of the test solution absorbed during determination, mL;
c——--The actual concentration of sodium hydroxide standard titration solution, mol/L; m.…The mass of the sample, g;
. (1)
0.09911--The mass of ammonium bisulfite expressed in grams equivalent to 1.00mL sodium hydroxide standard titration solution [c(NaOH)=1.000mol/L).
5.2.5 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. 656
HG/T2785—1996
The absolute error of the parallel determination results shall not exceed 0.15%. 5.3 Determination of ammonium sulfate content
5.3.1 Principle
In a neutral or weakly acidic solution, iodine oxidizes ammonium bisulfite and ammonium sulfite in the test solution into ammonium bisulfate and ammonium sulfate, respectively. Then, the excess iodine is titrated with sodium thiosulfate standard titration solution using starch as an indicator. The content of ammonium sulfite is calculated based on the consumption of sodium thiosulfate standard titration solution and the consumption of sodium hydroxide standard titration solution in the determination of ammonium bisulfite content. Reaction formula:
NH HSO3 +12+H2O→NH, HSO. +2HI(NH)2SO +I2+H2O→(NH),SO4 +2HI2Naz S,O, +I →Na S, O, +2Nal5.3.2 Reagents and materials
5.3.2.1 Sodium thiosulfate standard titration solution: c(Na.S2O.）=0.1000mol/L. 5.3.2.2 Iodine standard titration solution: c(1/2I2)=0.1mol/L; 5.3.2.3 Starch solution: 10g/L.
5.3.3 Determination
Accurately pipette 5ml~10mL solution (5.2.3.1) into a 250mL iodine volumetric flask containing 25mL iodine standard solution and shake well. Titrate with sodium thiosulfate standard titration solution until the solution turns light yellow, then add 2mL starch solution as an indicator. Continue titrating until the blue color just disappears as the end point.
While performing the above determination, perform a blank test according to the above determination procedure without adding the determination solution. 5.3.4 Expression of analysis results
The ammonium sulfite content (X2) expressed as mass percentage is calculated according to formula (2): (V3 - V2 — 2Vi)c × 0.058 07X
m×250
-the volume of sodium hydroxide standard titration solution consumed when titrating ammonium bisulfite, ml; where:
--the volume of sodium thiosulfate standard titration solution consumed during the determination, mL; V2
Vthe volume of sodium thiosulfate standard titration solution consumed in the blank test, mL; VA
0.058 07--
5.3.5 Allowable error
The volume of the test solution absorbed during the determination, mL;
The actual concentration of the sodium thiosulfate standard titration solution, mol/L; The mass of the sample, g;
The mass of ammonium sulfite in grams equivalent to 1.00ml. sodium thiosulfate standard titration solution Lc (NazS,O.)-1.000mol/L>
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute error of the parallel determination results shall not exceed 0.35%. 5.4 Total ammonium sulfite content
The sum of ammonium sulfite and ammonium bisulfite expressed in mass percentage (X.) is calculated according to formula (3): X, = X+X,
Where: X.-the measured content of ammonium bisulfite, %; X,--the measured content of ammonium sulfite, %.
5.5 Ammonium bisulfite/ammonium sulfite ratio
The ratio of ammonium bisulfite/ammonium sulfite expressed as mass percentage (X.) is calculated according to formula (4): X
·(4)
HG/T 2785-1996
Wherein: X1--the measured content of ammonium bisulfite, %; X2--the measured content of ammonium sulfite, %. 5.6 Determination of ammonium thiosulfate content
5.6.1 Principle
When the sample is at pH 5~6, use starch solution as indicator and formaldehyde solution as masking agent, and titrate the ammonium thiosulfate in the test solution with iodine standard titration solution. The content of ammonium thiosulfate is calculated based on the amount of iodine solution used. Reaction formula:
2(NH),S,O +I2 -www.bzxz.net
5.6.2 Reagents and materials
5.6.2.1 Formaldehyde.
5.6.2.2 Ethyl sodium.
5.6.2.3 Glacial acetic acid.
(NH),S,O+2NH,1
5.6.2.4 Glacial acetic acid-sodium acetate buffer solution (pH approximately equal to 6): Weigh 100g sodium acetate (CH.COONa·3H,O), dissolve it in water, add 5.7mL glacial acetic acid, and dilute to 1000mL. 5.6.3 Determination
Weigh about 13 g of sample (accurate to 0.0002 g), place in a 250 mL iodine volumetric flask containing 10 mL formaldehyde, shake well, let stand for 3 min, add 20 mL buffer solution, 2 mL starch solution, then add ice cubes, and titrate with iodine standard titration solution (5.3.2.2) until blue. 5.6.4 Expression of analysis results
The content of ammonium thiosulfate expressed as mass percentage (X,) is calculated according to formula (5): X = Vc×0.1482×100
Wherein: V——the volume of the standard iodine titration solution consumed in the titration, mL; c——the actual concentration of the standard iodine titration solution, mol/L; m——the mass of the sample, g;
(5)
0.148 2——the mass of ammonium thiosulfate expressed in grams equivalent to 1.00mL of the standard iodine titration solution [c(I.)=1.00mol/L).
5.6.5 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute error of the parallel determination results shall not exceed 0.008%. 6 Marking, labeling, and packaging
6.1 Tank trucks or storage tanks and plastic bags used to transport ammonium bisulfite should have obvious markings, including: manufacturer name, address, product name, trademark, grade, specification, date of manufacture, batch number, net weight of product, etc. 6.2 Ammonium bisulfite is loaded in railway tank trucks, automobile tank trucks, storage tanks, and plastic bags, and the filling factor is 0.85 or 85% of the container volume. During storage and transportation, it should be filled according to this standard.
6.3 Ammonium bisulfite is easily oxidized and decomposed, and the storage time should not exceed one month. 658
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