Some standard content:
HG/T2784—1996
This standard is a revision of ZB/TG12003.—1987 "Ammonium sulfite for industrial use". This standard differs from the original standard in the following aspects:
The indicator used in the determination of solid ammonium sulfite in this standard is changed from the phenolphthalein-methyl green mixed indicator used in the original standard to the phenolyl 1
thymol blue mixed indicator.
2 The index items are adjusted and the free water index is cancelled. 3 The allowable error in the determination of solid ammonium sulfite is adjusted. 4 The unit g/L expressing the content of liquid ammonium sulfite in the original standard is changed to mass percentage. This standard will replace ZB/TG12003—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 is Nanjing Chemical Industry (Group) Corporation Research Institute. The main drafters of this standard are Zhang Ruai, Zhao Yifang and Li Xiuling. This standard was first issued in 1987.
Chemical Industry Standard of the People's Republic of China
Industrial Ammonium Sulfite
HG/T 2784--1996
Replaces HG/TG12003-1987
This standard specifies the requirements, sampling, test methods, and marking, labeling, and packaging of industrial ammonium sulfite. This standard applies to solid ammonium sulfite and liquid ammonium sulfite products obtained by recovering sulfur dioxide from sulfuric acid tail gas using ammonium bicarbonate or other ammonia sources as raw materials.
Molecular formula of solid ammonium sulfite: (NH4), SO,·H,ORelative molecular weight: 134.15 (according to the 1991 international relative atomic mass)Molecular formula of liquid ammonium sulfite: (NH.), SO3Relative molecular weight: 116.14 (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 published, the versions shown are valid. All standards will be revised, and the parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T 601-
GB/T 603—1988
GB/T1250-
GB/T 6678-
GB/T 6680-
GB/T 8946-1988
GB/T 8947— 1988
GB/T 9724—1988
3 Requirements
Chemical reagents Preparation of standard solutions for titration analysis (volume analysis) Preparation of preparations and products used in test methods (neqISO6353-1:1982) Chemical reagents
Methods for expressing and determining limit values General rules for sampling of chemical products
General rules for sampling of liquid chemical products
Specifications and test methods for water used in analytical laboratories (eqv1SO3696:1987) Plastic woven bags
Composite plastic woven bags
General rules for pH determination of chemical reagents
Solid ammonium sulfite should meet the requirements of Table 1. Table 1
-Water ammonium sulfite/%
Ammonium bisulfite or ammonium bicarbonate/%
Ammonium sulfate/%
3.2 Liquid ammonium sulfite should meet the requirements of Table 2. Approved by the Ministry of Chemical Industry of the People's Republic of China on January 23, 1996, 648
Qualified product
White or light yellow crystals
Implemented on January 1, 1997
Ammonium sulfite/%
4 Sampling
4.1 Solid ammonium sulfite is taken as one batch based on daily output, HG/T 2784—1996
First-class product
Light yellow liquid
Qualified product
4.2 Bagged solid ammonium sulfite Determine the number of sampling units as specified in 6.6 of GB/T6678. From the selected bags, insert the sampler into 2/3 of the depth to take samples. Use the quartering method to reduce the sample to about 1000g. Put the samples into two clean, dry brown wide-mouth bottles with stoppers and seal them. A label is attached to the bottle, indicating the manufacturer's name, product name, category, grade, batch number, sampling date and name of the sampler. One bottle is used for inspection, and the other bottle is kept for one month for reference. 4.3 Liquid ammonium sulfite loaded in railway tank cars or storage tanks and automobile tank cars is sampled in accordance with the provisions of Chapter 2 of GB/T6680, with each car or tank as a batch.
5 Test method
The reagents and water used in this standard are analytical pure reagents and grade 3 water that meets the provisions of GB/T6682 unless otherwise specified. The standard solutions, preparations and products required for the test are prepared and calibrated in accordance with the provisions of GB/T601 and GB/T603 unless otherwise specified. The rounded value comparison method specified in GB/T1250 is used to determine whether the test results meet the standards. 5.1 Determination of solid ammonium sulfite
5.1.1 Appearance
The chain is measured by the moon sight method.
5.1.2 Determination of ammonium sulfite monohydrate
5.1.2.1 Principle
In a neutral or weakly acidic solution, iodine oxidizes ammonium sulfite to form ammonium sulfate. Then, using starch solution as an indicator, the excess iodine is titrated with sodium thiosulfate standard titration solution until the blue color of the solution just fades away. The content of ammonium sulfate monohydrate is calculated from the consumption of sodium thiosulfate standard titration solution.
Reaction formula:
(NH4SO4)+I2+H2O-→(NH4SO4)+2HI2Na2S2O2+I2-→NazSO2+2Nal5.1.2.2 Reagents and materials
5.1.2.2.1 Sodium thiosulfate standard titration solution: cNazS2O2)=0.1mol/L. 5.1.2.2.2 Iodine standard titration solution: c(1/2 1z)=0.1 mol/L. 5.1.2.2.3 Starch indicator: 10g/L. 5.1.2.3 Determination
Use the difference subtraction method to quickly weigh 0.1g~0.15g of the sample (accurate to 0.0002g). Place it in a 250ml iodine volumetric flask containing 25ml of iodine standard titration solution, shake well, titrate with sodium thiosulfate standard titration solution until the solution turns light yellow, add 2mL of starch indicator and continue titrating until the blue color just fades to the end point. Keep this solution for the determination of ammonium sulfate content. While carrying out the above determination, do a blank test without adding the sample to correct the determination result. 5.1.2.4 Expression of analysis results
The content of ammonium sulfite monohydrate expressed as mass percentage (X,) is calculated according to formula (1): 649
Wherein: Vo-
HG/T2784—1996
Xi = (V.-Vi)c× 0.06708 × 100 -- XX 1.353 5
The volume of sodium thiosulfate standard titration solution consumed in blank test, mL; The volume of sodium thiosulfate standard titration solution consumed in determination, ml.; \The actual concentration of sodium thiosulfate standard titration solution, mol/L; The mass of the sample, g;
The content of ammonium bisulfite, %
The mass of monohydrate ammonium sulfite expressed in grams equivalent to 1.00mL sodium thiosulfate standard titration solution [c(Na2S,)=1.000mol/L);
The coefficient of ammonium bisulfite converted to monohydrate ammonium sulfite (134.15/99.11). 5.1.2.5 Allowable difference
The arithmetic mean of the parallel determination results shall be taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.40%. 5.1.3 Determination of ammonium sulfate content
5.1.3.1 Principle
Ammonium sulfate in the sample reacts with formaldehyde to generate hexamethylenetetramine and sulfuric acid in an equal mole to ammonium sulfate. Using phenolphthalein-thymol blue mixed solution as an indicator, titrate with sodium hydroxide standard titration solution until the solution turns purple. The content of ammonium sulfate is calculated from the consumption of sodium hydroxide standard titration solution.
Reaction formula:
2(NH4) SO4 +6CH20 (CH2).N4 +2H, SO4 +6H20H2 SO4 +2NaOH →Na2 SO +2H2 O5.1.3.2 Reagents and materials
5.1.3.2.1 Sodium hydroxide standard titration solution: c(NaOH)=0.1mol/1. 5.1.3.2.2 Phenol ethanol solution: 50g/I. 5.1.3.2.3 Thymol blue ethanol solution: 50 g/L. 5.1.3.2.4 Phenol-thymol blue mixed indicator: use one part of phenol ethanol solution (5.1.3.2.2) and one part of thymol blue ethanol solution (5.1.3.2.3). 5.1.3.2.5 Methyl red ethanol solution: 1g/L. 5.1.3.2.6 Formaldehyde.
5.1.3.2.7 Formaldehyde neutral solution: 1+1. Use phenolphthalein-thymol blue mixed indicator (5.1.3.2.4) as the indicator and neutralize with sodium hydroxide standard titration solution (5.1.3.2.1) until the solution turns purple. If the volume of the solution is greater than 100mL, use a pH meter to measure the pH of the solution to 8.5. 5.1.3.2.8 Sodium hydroxide solution: 80g/L. 5.1.3.3 Determination
Add one drop of methyl red ethanol solution as an indicator to the solution after the determination of ammonium sulfite monohydrate (5.1.2.3). The solution is now red. Adjust the color to a light red with sodium hydroxide solution, and then neutralize it with a standard sodium hydroxide solution until it just turns yellow. Immediately add 10 mL of neutral formaldehyde solution, shake well, and let stand for 3 minutes. Add 5 drops of phenol-thymol blue mixed indicator, and titrate with a standard sodium hydroxide solution until the solution turns purple, which is the end point.
5.1.3.4 Expression of analysis results
The ammonium sulfate content (X?) expressed as mass percentage shall be calculated according to formula (2) or formula (3) according to the presence of ammonium bisulfite or ammonium bicarbonate in the sample:
X Vc×0.066 07×100 X ×0.985 0 - X ×0.66 6m
Wherein:
HG/T 2784—1996
--the volume of sodium hydroxide standard titration solution consumed during titration, mL;--the actual concentration of sodium hydroxide standard titration solution, mol/L;--the mass of the sample, g;
--the percentage of ammonium sulfite in water, %;
--the percentage of ammonium bisulfite, %;
0.066 07-
The mass of ammonium sulfate in grams equivalent to 1.00mL sodium hydroxide standard titration solution Cc(NaOH)=1.000mol/L>;
The coefficient of ammonium sulfite in water converted to ammonium sulfate (132.14/134.15);0. 985 0
Wherein:
-The coefficient of ammonium bisulfite in water converted to ammonium sulfate (132.14/99.11×2). X2 = Vc× 0. 066 07、
× 100 - X; × 0. 985 0 - X4 × 0. 835 7m
The volume of sodium hydroxide standard titration solution consumed during titration, mL; The actual concentration of sodium hydroxide standard titration solution, mol/L; m——The mass of the sample, g;
X,——The percentage of ammonium sulfite in water, %; X. —-Ammonium bicarbonate percentage, %;
(3)
-The mass of ammonium sulfate in grams equivalent to 1.00mL of sodium hydroxide standard titration solution Cc (NaOH) = 1.000mol/L]0. 066 07-
Ammonium sulfate;
0.9850--The coefficient of ammonium sulfite converted to ammonium sulfate (132.14/134.15);0.8357--The coefficient of ammonium bicarbonate converted to ammonium sulfate (132.14/79.06×2). 5.1.3.5 Allowable difference
The arithmetic mean of the parallel determination results shall be taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.50%. 5.1.4 Determination of ammonium bisulfite content
5.1.4.1 Principle
Ammonium bisulfite in the sample is oxidized by hydrogen peroxide 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 solution turns yellow-green. The content of ammonium bisulfite is calculated from the consumption of sodium hydroxide standard titration solution.
Reaction formula:
NH, HSO: +H,O, --NH, HSO +H,O2NH HSO +2NaOH -(NH ) SO. +Na2 SO +2H,05.1.4.2 Reagents and materials
5.1.4.2.1 Indigo (chemically pure) ethanol solution: 1g/L. 5.1.4.2.2 Methyl red-indigo mixed indicator: Prepared by adding 1 part of methyl red ethanol solution (5.1.3.2.5) to 2 parts of indigo ethanol solution.
5.1.4.2.3 Hydrogen peroxide solution: 3%. Use methyl red-indigo mixed indicator as the indicator and neutralize with sodium hydroxide standard titration solution (5.1.3.2.1) until the solution changes from red to yellow-green. 5.1.4.3 Determination
Use the difference subtraction method to quickly weigh about 0.5g of the sample (accurate to 0.0002g), place it in a 250mL conical flask containing 15mL of 3% hydrogen peroxide solution and about 30ml of water, and shake the hook. Add 5 drops of methyl red-indigo mixed indicator, the solution is red at this time, and titrate with sodium hydroxide standard titration solution (5.1.3.2.1) until the solution turns yellow-green as the end point. 5.1.4.4 Expression of analysis results
The content of ammonium bisulfite expressed as mass percentage (X) is calculated according to formula (4): 651
Wherein:
0. 099 11--
HG/T 2784-1996
Vc X 0. 099 11
The volume of sodium hydroxide standard titration solution consumed during the determination, mL: the actual concentration of sodium hydroxide standard titration solution, mol/l.; the mass of the sample, g;
The mass of ammonium bisulfite equivalent to 1.00mL of sodium hydroxide standard titration solution Cc(NaOH)=1.000moi/L) expressed in grams.
5.1.4.5 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.10%. 5.1.5 Determination of ammonium bicarbonate content
5.1.5.1 Principle
According to the principle of acid-base neutralization reaction, methyl red-indigo mixed solution is used as an indicator and titrated with hydrochloric acid standard titration solution until the solution turns slightly red. The content of ammonium bicarbonate is calculated from the consumption of hydrochloric acid standard titration solution. Reaction formula:
NH, HCO: +HCI -
+NH CI+CO,+H,O
5.1.5.2 Reagents and materials
Hydrochloric acid standard titration solution: c(HCI)=0.1 mol/L. 5.1.5.3 Determination
Use the difference subtraction method to quickly weigh about 0.5g of the sample (accurate to 0.0002g), place it in a 250mL conical flask containing 15mL of hydrogen peroxide solution (5.1.4.2.3) and about 30ml of water, and shake well. Add 5 drops of methyl red-indigo mixed indicator (5.1.4.2.2), and the solution will turn yellow-green. Titrate with hydrochloric acid standard titration solution until the solution turns slightly red. 5.1.5.4 Expression of analytical results
The content of ammonium bicarbonate (X) expressed as a mass percentage is calculated according to formula (5): X4 YcX0. 077 06 × 100
-the volume of hydrochloric acid standard titration solution consumed in titration, mL; where: V
-the actual concentration of hydrochloric acid standard titration solution, mol/L; m-Www.bzxZ.net
0. 077 06---
the mass of the sample, g;
the mass of ammonium bicarbonate expressed in grams equivalent to 1.00mL hydrochloric acid standard titration solution Ec(HCI)1.000mol/LJ.
5.1.5.5 Allowable difference
Take the arithmetic mean of the parallel determination results as the determination result. The absolute difference of the parallel determination results shall not exceed 0.10%. 5.2 Determination of liquid ammonium sulfite
5.2.1 Appearance
Determine by visual method.
5.2.2 Determination of ammonium sulfite content
5.2.2.1 Preparation of sample
Weigh about 0.6g of sample (accurate to 0.0002g), put it into a 250mL volumetric flask containing about 150mL of water, dilute with water to the scale, shake well, and use it as the test solution.
5.2.2.2 Determination
Accurately pipette 5mL of test solution into a 250mL iodine volumetric flask containing 25mL of iodine standard solution (5.1.2.2.2), and shake well. After titrating with sodium thiosulfate standard titration solution (5.1.2.2.1) until it turns pale yellow, add 2 mL of starch solution (5.1.2.2.3) as an indicator and continue titrating until the blue color of the solution just fades away. While performing the above determination, do a blank test without adding test solution to correct the determination results. 5.2.2.3. Expression of analysis results
The content of ammonium sulfite expressed as mass percentage (X,) is calculated according to formula (6): X; = V. -Vi)c× 0. 058 07 ×m×250
Wherein:
The volume of sodium thiosulfate standard titration solution consumed during blank test, ml; The volume of sodium thiosulfate standard titration solution consumed during titration, mL; The actual concentration of sodium thiosulfate standard titration solution, mol/L; The mass of the sample, g;
(6)
The mass of ammonium sulfite equivalent to 1.00mL sodium thiosulfate standard titration solution Cc (Na2SzO) = 1.000mol/L) expressed in grams.
5.2.2.4 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.15%. 5.2.3 Determination of pH value
According to 5.6 of GB/T9724.
6 Marking, labeling and packaging
6.1 Solid ammonium sulfite is packaged in plastic woven bags lined with dark high-density polyethylene or polyvinyl chloride plastic bags. The net weight of each bag is 25kg, 40kg or 50kg. When 10 bags are randomly selected, the average deviation is no more than ±0.2kg. When a bag is randomly selected and weighed, the deviation is no more than ±0.3kg. The inner bag is sealed with heat or tied with a thin rope. 6.2 The packaging of solid ammonium sulfite leaving the factory should have firm and obvious markings, including: manufacturer name, factory address, product name, trademark, grade, specification, date of manufacture, batch number, product net weight and sun protection mark. 6.3 Solid ammonium sulfite should be stored in a cool place and the bag should not be broken during transportation and storage. 6.4 Liquid ammonium sulfite is transported in railroad tank cars, automobile tank cars or plastic bags. The filling factor is 0.85 or 85% of the container volume. During storage and transportation, it should be filled according to this standard.
6.5 Each batch of liquid ammonium sulfite leaving the factory should have a quality certificate. The quality certificate includes the following contents: manufacturer name, trademark, standard number, grade, product production date, analysis results and inspection unit seal. 6.6 The effective storage period of solid ammonium sulfite is one month. 653
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