Some standard content:
Chemical Industry Standard of the People's Republic of China
Industrial Sodium Thiosulfate
Subject Content and Scope of Application
HG/T 2328 --- 92
This standard specifies the technical requirements, test methods, inspection rules, marking, packaging, transportation and storage of industrial sodium thiosulfate. This standard applies to industrial sodium thiosulfate. The product is mainly used in textile bleaching and dyeing, chemical fiber, papermaking, leather making and pesticide industries. Molecular formula: Na2S,0, 5H,0
Relative molecular mass: 248.19 (according to the international relative atomic mass in 1989) 2 Reference standards
GB 603
GB 1250
GB 6678
GB 6682
GB 8946
3 Technical requirements
3.1 Appearance
Packaging Storage and transportation Pictorial signs
Chemical reagents
Chemical reagents
Preparation of standard solutions for titration analysis (volume analysis) Preparation of standard solutions for impurity determination
Preparation of preparations and products used in test methods Chemical reagents
Expression and determination methods of limit values General rules for sampling of chemical products
Specifications for laboratory water
Plastic woven bags
Colorless or slightly yellowish transparent monoclinic crystals. 2 Industrial sodium thiosulfate should meet the requirements of the following table. 3.2
Sodium thiosulfate (NazS,O:·5H20) content, % Water-insoluble matter content, %
Sulfide (as Na2S) content, %
Iron (Fe) content, %
pH value (200g/L.solution)
4 Test method
Superior quality
First quality
The reagents and water used in this standard, unless otherwise specified, refer to analytical pure reagents and Grade 3 water specified in GB6682. Approved by the Ministry of Chemical Industry of the People's Republic of China on June 1, 1992 and implemented on September 1, 1992
HG/T2328-92
The standard solutions, impurity standard solutions, preparations and products required in the test, unless otherwise specified, shall be prepared in accordance with the provisions of GB601, GB602 and GB603.
4.1 Determination of sodium thiosulfate content
4.1.1 Method summary
In a weakly acidic medium, use formaldehyde to mask sodium sulfite, use starch as an indicator, and titrate with iodine standard titration solution until the solution turns blue.
4.1.2 Reagents and materials
4.1.2.1 Formaldehyde (GB685): use phenol (GB10729) solution (10g/L) as an indicator, and neutralize with sodium hydroxide solution (2g/L) until it turns pink;
4.1.2.2 Acetic acid (GB676)-sodium acetate (GB693) buffer solution (pH～6); 4.1.2.3 Iodine (GB675) standard titration solution: c (1/212) about 0.1mol/L; 4.1.2.4 Soluble starch indicator solution: 10g/L. 4.1.3 Analysis steps
Weigh about 10g of sample, accurate to 0.0002g, dissolve in water, transfer to a 250mL volumetric flask, dilute to scale with water, and shake well. Use a pipette to transfer 25mL (equivalent to 1g of sample), add 5mL of formaldehyde solution and 10ml of acetic acid-sodium acetate buffer solution. Titrate with iodine standard titration solution. When approaching the end point, add 1-2mL of starch indicator solution and continue titrating until the solution turns blue and does not fade within 30s. This is the end point. 4.1.4 Expression of analysis results
The sodium thiosulfate (Na2S2O:·5H,O) content X expressed as a mass percentage is calculated according to formula (1): Xi =: V×0,248 2 × 100
248. 2 X c- V
Wherein: c is the actual concentration of the iodine standard titration solution, mol/L; V is the volume of the iodine standard titration solution consumed in the titration, mL; m is the mass of the sample, g;
(1)
is the mass of 0.248 2
of sodium thiosulfate equivalent to 1.00mL of iodine standard titration solution [c (1/2I2) = 1.000mol/L) expressed in grams.
4.1.5 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 0.2%. 4.2 Determination of water-insoluble matter content
4.2.1 Method summary
Dissolve the sample in hot water, filter with a filter, wash, dry and weigh. 4.2.2 Reagents and materials
4.2.2.1 Iodine (GB675) solution: c(1/2I2) about 0.1 mol/L. 4.2.3 Instruments and equipment
4.2.3.1 Crucible filter: filter plate pore size 5~15μm4.2.4 Analysis steps
Weigh about 20g of sample, accurate to 0.1g, place in 150mL hot water, and filter with a crucible filter that has been dried to constant weight at 105~110℃ in advance. Wash with hot water until the filtrate does not contain sodium thiosulfate (use a trace iodine solution with starch to check for non-fading). Move the crucible filter together with the insoluble matter into an electric drying oven and dry at 105-110°C to constant weight. 4.2.5 Expression of analysis results
The water-insoluble matter content X expressed as mass percentage is calculated according to formula (2): 138
HG/T2328-92
m2m2 × 100bZxz.net
-mass of volute filter and water-insoluble matter, g; where m,-
-mass of volute filter, g;
mass of sample, g.
4.2.6 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 0.005%. 4.3 Determination of sulfide content
4.3.1 Method summary
Under alkaline conditions, lead ions react with sulfur ions and visually compare with standard colorimetric solution. 4.3.2 Reagents and materials
4.3.2.1 Lead acetate (HG3--974) alkaline solution; 4.3.2.2 Sulfide standard solution: 1 mL of solution contains 0.01 mg Na2S. (2)
Weigh 0.308 g of sodium sulfide (NazS·9H,O) and dissolve it in water. Transfer it to a 1000 mL volumetric flask, dilute to the mark, and shake well. Transfer 10 mL of the solution to a 100 mL volumetric flask, dilute to the mark, and shake well. This standard solution is prepared before use. 4.3.3 Analysis steps
Weigh 2.0 ± 0.1 g of the sample, dissolve it in 10 mL of water, and add 0.5 mL of lead acetate (alkaline solution). Dilute to the mark in a 50mL colorimetric tube and shake well. The color should not be darker than the standard colorimetric solution. Preparation of standard colorimetric solution: Take a certain volume of sulfide standard solution as specified below and treat it in the same way as the test sample. Superior product
First-class product·
4.4 Determination of iron content
4.4.1 Summary of method
In an alkaline medium, use hydrogen peroxide to oxidize sodium thiosulfate and divalent iron. Then, in an acidic medium, add potassium thiocyanate to develop the color, extract with n-butanol, and compare visually with the standard colorimetric solution. 4.4.2 Reagents and materials
4.4.2.1 Ammonia water (GB631) 1+2 solution;
4.4.2.2 Hydrogen peroxide (GB6684) 1+1 solution; 4.4.2.3 Hydrochloric acid (GB622) 1+1 solution;
4.4.2.4 Potassium thiocyanate (GB648)-n-butanol (HG3--1012) solution: dissolve 10g potassium thiocyanate in 10mL water, add 90mL n-butanol, and shake vigorously to mix evenly;
4.4.2.5 Iron standard solution: 1mL solution contains 0.1mg iron. 4.4.3 Analysis steps
Weigh 5.0±0.1g sample, dissolve in 20mL water, add 5mL nitrogen solution, slowly add 40mL hydrogen peroxide solution in portions, let stand for 10min, evaporate to dryness on a steam bath; then add 5mL hydrochloric acid solution and 5mL water, heat to boiling, dilute with water to 100mL, pipette 5mL into a 50mL colorimetric tube, add 15mL potassium thiocyanate-n-butanol solution, shake vigorously for 1min; the red color of the alcohol layer shall not be darker than that of the standard colorimetric solution.
Preparation of standard colorimetric solution: Take a certain volume of iron standard solution according to the following regulations and treat it in the same way as the sample. Superior products
Superior products·
4.5 Determination of pH value
4.5.1 Method Summary
Immerse the glass electrode and saturated calomel electrode in the same solution to be tested to form a primary cell, whose potential is related to the pH value of the solution. By measuring the potential of the primary cell, the pH value of the solution can be obtained. 4.5.2 Reagents and materials
4.5.2.1 Water without carbon dioxide.
4.5.3 Instruments and equipment
4.5.3.1 Acidity meter: the graduation value is 0.02 pH unit; 4.5.3.2 Glass electrode;
4.5.3.3 Saturated calomel electrode.
4.5.4 Analysis steps
Weigh 20.0±0.1g of the sample, dissolve it in 80mL of water without carbon dioxide, dilute to 100mL, adjust the temperature of the test solution to 20℃, and measure with an acidity meter.
4.5.5 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 0.2 pH units. 5 Inspection rules
5.1 Industrial sodium thiosulfate shall be inspected by the quality supervision and inspection department of the manufacturer in accordance with the provisions of this standard. The manufacturer shall ensure that all products leaving the factory meet the requirements of this standard. Each batch of products leaving the factory shall be accompanied by a quality certificate, which includes: the name of the manufacturer, product name, grade, net weight, batch number or production date, proof that the product quality meets this standard and the number of this standard. 5.2 The user unit has the right to accept the industrial sodium thiosulfate received in accordance with the provisions of this standard. 5.3 Each batch of industrial sodium thiosulfate shall not exceed 60t. 5.4 The sampling of industrial sodium thiosulfate shall determine the number of sampling units in accordance with Article 6.6 of GB6678. When sampling, the sampler shall be inserted vertically from the center of the package to 3/4 of the depth of the material layer for sampling. After mixing the sample, reduce it to no less than 500g by quartering, and pack the sample into two clean, dry wide-mouth bottles with ground stoppers and seal them. Paste labels on the bottles, indicating the manufacturer's name, product name, grade, batch number, sampling date and the name of the sampler. One bottle is used for inspection and the other is used as a spare, with a shelf life of at least 1 month. 5.5 If one indicator of the inspection result does not meet the requirements of this standard, re-sample from twice the amount of bags for verification. Even if one indicator of the verification result does not meet the requirements of this standard, the entire batch of products cannot be accepted. 5.6 When the supply and demand parties have objections to the product quality, they shall be handled in accordance with the provisions of the "Interim Measures for National Product Quality Arbitration Inspection". 5.7 The rounded value comparison method specified in GB1250 shall be used to determine whether the inspection results meet the standards. 6 Marking, packaging, transportation, storage
6.1 The packaging bags of industrial sodium thiosulfate should have firm and clear markings, including: manufacturer name, product name, trademark, grade, net weight, batch number or production date and this standard number, as well as the mark 7 "wet-afraid" mark specified in GB1916.2 Industrial sodium thiosulfate is double-packed. The inner packaging is a polyethylene plastic film bag with a thickness of 0.05mm, and the inner bag is 100mm longer than the outer bag; the outer packaging bag is a plastic woven bag with an effective width of 550mm and an effective length determined by negotiation between the supply and demand parties. Its performance and inspection methods should comply with the provisions of GB8946C. The net weight of each bag of industrial sodium thiosulfate is 50kg. 6.3 For the packaging of industrial sodium thiosulfate, the inner bag shall be tied with vinyl rope or other rope of equivalent quality, or sealed with other equivalent methods; the outer bag shall be folded at a distance of not less than 30mm from the bag edge, and sewed with vinyl thread or other thread of equivalent quality at a distance of not less than 15mm from the bag edge, with a stitch length of 7~~12mm, neat stitching, uniform stitch length, and no leakage or skipping. 6.4 Industrial sodium thiosulfate shall be covered during transportation to prevent rain and moisture. 6.5 Industrial sodium thiosulfate shall be stored in a cool and dry place to prevent rain, moisture, sunlight and heat. 4.10
Additional Notes:
HG/T2328-92
This standard is proposed by the Science and Technology Department of the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of Tianjin Chemical Research Institute of the Ministry of Chemical Industry. This standard is drafted by Tianjin Chemical Research Institute of the Ministry of Chemical Industry, Shanghai Fluorescent Materials Factory and Jinzhou Ferroalloy Factory. The main drafters of this standard are Su Peiji, Li Wenqiang, Zhang Meifang, Gao Ruili, Huang Yadong and Wang Shunguo. This standard adopts the Soviet national standard IOCT244--76 "Technical Conditions for Crystallized Sodium Thiosulfate".
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