Some standard content:
Chemical Industry Standard of the People's Republic of China
Industrial Basic Chromium Sulfatewww.bzxz.net
Subject Content and Scope of Application
HG/T 2678-95
This standard specifies the technical requirements, test methods, inspection rules, as well as marking, packaging, transportation and storage of industrial basic chromium sulfate. This standard applies to industrial basic chromium sulfate (also known as basic chromium sulfate, chromium salt essence) obtained by acidifying sodium dichromate or chromium-containing by-products with sulfuric acid or sodium bisulfate and reducing them. It is mainly used for leather and mordant dyeing. Molecular formula: Cr(OH)m(SO,)·XH20
2 Reference standards
GB 191
Picture mark for packaging, storage and transportation
GB/T 601
GB/T 602
GB/T603
GB 1250
Chemical reagents-Preparation of standard solutions for titration analysis (volume analysis) Chemical reagents
Preparation of standard solutions for impurity determination
Preparation of preparations and products used in chemical reagent test methods Methods for expressing and determining limit values GB/T 6678
GB/T 6682
GB 8946
GB 8947
3 Product classification
General rules for sampling of chemical products
Specifications and test methods for water used in analytical laboratoriesPlastic woven bags
Composite plastic woven bags
Industrial basic chromium sulfate is divided into two categories according to its use: Category I products are high-content, low-alkalinity products, mainly used for sheepskin; Category II products are low-content, high-alkalinity products, mainly used for cowhide and pig leather.4 Technical requirements
4.1 Appearance: amorphous dark green powder or flakes.4.2 Industrial basic chromium sulfate should comply with Meet the requirements of the following table: Index
Chromium trioxide (Cr20) content, %
Alkalinity, %
Iron (Fe) content, %
Water insoluble content, %
For products with different alkalinity required by users, the supply and demand parties shall negotiate. Approved by the Ministry of Chemical Industry of the People's Republic of China on April 5, 1995 568
32～34
21～23
1996-01-01 implementation
5 Test method
HG/T 2678—95
The reagents and water used in this standard, unless otherwise specified, refer to analytically pure reagents and grade tertiary water specified in GB/T6682. The standard titration solutions, impurity standard solutions, preparations and products used in the test, unless otherwise specified, are prepared in accordance with the provisions of GB/T601, GB/T602 and GB/T603. 5.1 Determination of chromium trioxide content
5.1.1 Summary of the method
The trivalent chromium in the sample is oxidized to hexavalent chromium with sodium peroxide, reacted with potassium iodide in a neutral medium, and the precipitated iodine is titrated with a standard sodium thiosulfate titration solution, with starch as the indicator to indicate the end point. 5.1.2 Reagents and materials|| tt||5.1.2.1 Sulfuric acid (GB/T625): 1+4 solution; 5.1.2.2 Sodium peroxide;
5.1.2.3 Potassium iodide (GB/T1272);
5.1.2.4 Soluble starch: 5g/1. solution, freshly prepared. 5.1.2.5 Sodium thiosulfate (GB/T637): c (NazS,O) is about 0.1mol/L standard titration solution. 5.1.3 Analysis steps
Weigh 5g of sample (accurate to 0.0002g), place it in a 150mL beaker, add 70~80C hot water to dissolve the sample, cool it down and transfer it to a 500ml volumetric flask, dilute it to the scale with water, and shake it well. This solution is solution A. Solution A is also used to determine alkalinity and iron content. Use a pipette to transfer 25mL of solution A, place it in a 500mL iodine volumetric flask, add about 1g of sodium peroxide, add 100mL of water, slowly heat to boil to oxidize chromium, continue heating until the volume of the solution is reduced to less than 25mL, stop heating, rinse the inner wall of the bottle with a small amount of water, cool to room temperature, neutralize with sulfuric acid solution until it turns orange-yellow, add 10mL of sulfuric acid solution, add 2g of potassium iodide, place in a dark place for 10min, add 150mL of water, titrate with sodium thiosulfate standard titration solution until the solution turns yellow-green, add 3mL of starch indicator solution, continue titrating until the solution turns bright green as the end point, and perform blank tests in between.
5.1.4 Expression of analysis results
The chromium trioxide (Cr2O.) content X expressed as mass percentage is calculated according to formula (1): Xx VV) ·cX0 025 33×100
m×500
_ 50. 66X(V-Vo) :c
-the volume of sodium thiosulfate standard titration solution consumed by titrating the test solution, mL; where: V
V.-the volume of sodium thiosulfate standard titration solution consumed by titrating the blank test solution, mL; --the actual concentration of sodium thiosulfate standard titration solution, mol/L: m-the mass of the sample, g
(1)
-the amount of trioxygen in grams equivalent to 1.00mL of sodium thiosulfate standard titration solution (c(NazS,0,)=1.000mol/L) 0.025 33-
The mass of chromium sulfate.
5.1.5 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result, and the absolute difference between the two parallel determination results shall not exceed 0.2%. 5.2 Determination of alkalinity
5.2.1 Summary of method
Use phenol as an indicator and titrate part of the acidic chromium sulfate component in the test solution with sodium hydroxide solution to obtain the alkalinity in the original sample. 5.2.2 Reagents and materials
5.2.2.1 Sodium hydrofluoride (GB/T629) standard titration solution: c (NaOH) is about 0.1 mol/L; 5.2.2.2 Phenol (GB/T10729) indicator solution: 10g/1.569
wW.bzsosocom5.2.3 Analysis steps
HG/T 2678--95
In a 500mL porcelain evaporating dish, add 400mL of boiling water, add 15-20 drops of phenolphthalein indicator solution, and titrate with sodium hydroxide standard titration solution until a reddish color appears. Accurately transfer 50mL of solution A (5.1.3) into the porcelain evaporating dish, heat to a slight boil, and titrate with sodium hydroxide standard titration solution while hot until the generated chromium hydroxide precipitate changes from green to a stable light purple-red (observed from the clear liquid above), and remains unchanged for 1 minute. This is the end point.
5.2.4 Expression of analytical results
The alkalinity X expressed as a mass basis percentage is calculated according to formula (2): 2V.cV,×100
Where: V,---consumption of sodium hydroxide standard titration solution Volume, mL; i ~ actual concentration of sodium hydroxide standard titration solution, mol/L; V -- volume of sodium thiosulfate standard titration solution consumed in 5.1.3, ml; c -- actual concentration of sodium thiosulfate standard titration solution in 5.1.3, mol/L; 2 -- coefficient of transfer solution A (5.1.3). 5.2.5 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result, and the absolute difference between the two parallel determination results shall not exceed 1.0%. 5.3 Determination of iron content
5.3.1 Summary of method
In an acidic medium, ammonium persulfate is used to oxidize the divalent iron ions to trivalent iron, and potassium thiocyanate-butanol solution is added to generate a red ferric thiocyanate complex for colorimetry.
5.3.2 Reagents and materials
5.3.2.1 Hydrochloric acid (GB/T622) solution: 1+1; 5.3.2.2 Ammonium persulfate (GB/T655); 5.3.2.3 Potassium thiocyanate (GB/T648) butanol (GB/T12590) solution: Dissolve 10g potassium thiocyanate in 10mL water, add 90mL butanol, and shake vigorously.
5.3.2.4 Iron standard solution: 1mL solution contains 0.01mgFe. Use a pipette to transfer 10mL of the iron standard solution prepared according to GB/T602, place it in a 100mL volumetric flask, dilute to the mark with water, and shake. This solution is prepared before use.
5.3.3 Instruments and equipment
Colorimetric tube: 50mL;
5.3.4 Analysis steps
Use a pipette to transfer 10mL of solution A (5.1.3) Place in a 100mL beaker, add 8mL hydrochloric acid solution, boil for 2min, cool, transfer to a 100mL volumetric flask, dilute to scale, and shake well. Use a pipette to transfer 10mL of the solution, place in a 50mL colorimetric tube, add 2mL hydrochloric acid solution, add about 50mg ammonium persulfate, add 15mL potassium thiocyanate-butanol solution, dilute to scale with water, shake for 1min, and the red color of the butanol layer should not be darker than the standard colorimetric solution.
Standard colorimetric solution is to take 1mL of iron standard solution, put it in a 50mL colorimetric tube, add 10mL of water, and start from "add 2mL of hydrochloric acid solution" and treat it in the same way as the test solution. 5.4 Determination of water-insoluble content
5.4.1 Summary of method
Dissolve the sample in water, filter and wash, dry and weigh the residue. 5.4.2 Instruments and equipment
Glass filter: The pore size of the filter plate is 5 to 15gμm. 5.4.3 Analysis steps
HG/T 2678—95
Weigh 5g of sample (accurate to 0.0002g), place in a 500ml beaker, add 250mL of hot water at 70-80°C to dissolve the sample, filter while hot through a crucible filter that has been dried to constant weight at 105-110°C, and wash the residue repeatedly with water until the washing liquid is colorless. Dry the crucible filter at 105-110°C to constant weight. 5.4.4 Expression of analysis results
The water-insoluble content Xa expressed as a mass basis percentage is calculated according to formula (3): m2-mi×100
Where: m2——the mass of the crucible filter and the residue after drying, g;m—mass of the crucible filter, g;
m——mass of the test material, g.
5.4.5 Allowable error
The arithmetic mean of the parallel determination results shall be taken as the determination result, and the absolute difference of the parallel determination results shall not exceed 0.05%. 6 Inspection rules
(3)
6.1 All technical indicators listed in this standard are type inspection items, among which chromium trioxide and alkalinity are factory inspection items. Under normal production conditions, type inspection shall be carried out at least once every three months. 6.2 Industrial basic chromium sulfate shall be inspected by the quality supervision and inspection department of the manufacturer in accordance with the provisions of this standard. Inspection, the manufacturer shall ensure that all industrial basic chromium sulfate products shipped out of the factory meet the requirements of this standard. Each batch of products shipped out of the factory shall be accompanied by a quality certificate, which includes: manufacturer name, product name, category, net weight, batch number or production date, proof that the product quality complies with this standard and the number of this standard. 6.3 The user unit has the right to inspect and accept the industrial basic chromium sulfate products received in accordance with the provisions of this standard. 6.4 Each batch of products shall not exceed 20t.
6.5 Determine the number of sampling units in accordance with the provisions of Article 6.6 of GB/T6678. Each plastic woven bag is a packaging unit. When sampling, insert the sampler obliquely into the material Sampling is carried out at 2/3 of the layer depth. From each selected packaging unit, take out a sample of no less than 50g. Mix the collected samples and then reduce them to about 500g by quartering. Immediately put them into two clean and dry wide-mouth bottles with ground stoppers and seal them. Label the bottles with the following information: manufacturer name, product name, category, batch number, sampling date and name of the sampler. One bottle is used for inspection and the other is kept for three months for future reference. 6.6 If one of the indicators in the inspection results does not meet the requirements of this standard, re-sampling should be carried out from the packaging of twice the number of sampling units. Even if only one indicator in the inspection results does not meet the requirements of this standard, the entire batch of products cannot be accepted. 6.7 When the supply and demand parties have objections to the product quality, they shall be handled in accordance with the provisions of the "Product Quality Law of the People's Republic of China". 6.8 The rounded value comparison method specified in GB1250 shall be used to determine whether the inspection results meet the requirements of this standard. 7 Marking, packaging, transportation and storage
7.1 The packaging bags of industrial basic chromium sulfate should be firmly and clearly marked, including: manufacturer name, factory address, product name, trademark, category, net weight, batch number or production date and this standard number, as well as the "heat-afraid" mark and "wet-afraid" mark in GB191. 7.2 Industrial basic chromium sulfate can be packaged in polypropylene woven bags lined with plastic bags, and the inner packaging should be polyethylene plastic film bags, with specifications and dimensions: 1000mm×650mm , thickness is not less than 0.08mm, outer packaging uses polypropylene woven bags, specification size: 950mm×600mm, thickness 0.5mm.
When packaging, industrial basic chromium sulfate is put into a polypropylene woven bag lined with a polyethylene plastic film bag, and the remaining air in the bag is discharged. The inner bag is tied twice with a string and tied tightly. The outer bag is sewed with a bag sewing machine at a distance of not less than 17mm from the upper end of the bag, with a stitch length of 6~7mm, neat stitches, and uniform stitch length. There is no leakage or skipping. This product The net weight of each bag is 25kg. 7.3 Industrial basic chromium sulfate should be covered during transportation to prevent sun exposure, rain, and packaging damage. 7.4 Industrial basic chromium sulfate should be stored in a ventilated, dry warehouse to prevent sun exposure and moisture. 571
Additional instructions:
HG/T2678-95
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 Tianjin Chemical Industry Research Institute of the Ministry of Chemical Industry. This standard is under the jurisdiction of the Tianjin Chemical Industry Research Institute of the Ministry of Chemical Industry. The Tianjin Chemical Industry Research Institute, Zhangjiagang Xingda Chemical Factory, Jinan Yuxing Chemical Factory, Chongqing Dongfeng Chemical Factory, Changsha Chromium Salt Factory Gaoling Branch, Hubei Huangshi Inorganic Salt Factory, Qinghai Chromium Salt Factory, and Shanghai Chemical Light Industry Corporation were responsible for drafting. The main drafters of this standard are Liu Shuying, Zou Zhenqiu, Xu Zhuoliang, Wang Zhaolu, Du Jian, Cheng Xichuan, Luo Guibin, Di Guihua, and Ju Lei. This standard is not equivalent to the Japanese Industrial Standard JISK6506--77 "Industrial Basic Chromium Sulfate Test Method" and the specifications of Japan Co., Ltd.8 The rounded value comparison method specified in GB1250 shall be used to determine whether the test results comply with this standard. 7 Marking, packaging, transportation, storage
7.1 The packaging bags of industrial basic chromium sulfate should have firm and clear markings, including: manufacturer name, address, product name, trademark, category, net weight, batch number or production date and this standard number, as well as the "heat-afraid" mark and "moisture-afraid" mark in GB191. 7.2 Industrial basic chromium sulfate can be packaged in polypropylene woven bags lined with plastic bags, and the inner packaging is polyethylene plastic film bags, with specifications and dimensions: 1000mm×650mm , thickness is not less than 0.08mm, outer packaging uses polypropylene woven bags, specification size: 950mm×600mm, thickness 0.5mm.
When packaging, industrial basic chromium sulfate is put into a polypropylene woven bag lined with a polyethylene plastic film bag, and the remaining air in the bag is discharged. The inner bag is tied twice with a string and tied tightly. The outer bag is sewed with a bag sewing machine at a distance of not less than 17mm from the upper end of the bag, with a stitch length of 6~7mm, neat stitches, and uniform stitch length. There is no leakage or skipping. This product The net weight of each bag is 25kg. 7.3 Industrial basic chromium sulfate should be covered during transportation to prevent sun exposure, rain, and packaging damage. 7.4 Industrial basic chromium sulfate should be stored in a ventilated, dry warehouse to prevent sun exposure and moisture. 571
Additional instructions:
HG/T2678-95
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 Tianjin Chemical Industry Research Institute of the Ministry of Chemical Industry. This standard is under the jurisdiction of the Tianjin Chemical Industry Research Institute of the Ministry of Chemical Industry. The Tianjin Chemical Industry Research Institute, Zhangjiagang Xingda Chemical Factory, Jinan Yuxing Chemical Factory, Chongqing Dongfeng Chemical Factory, Changsha Chromium Salt Factory Gaoling Branch, Hubei Huangshi Inorganic Salt Factory, Qinghai Chromium Salt Factory, and Shanghai Chemical Light Industry Corporation were responsible for drafting. The main drafters of this standard are Liu Shuying, Zou Zhenqiu, Xu Zhuoliang, Wang Zhaolu, Du Jian, Cheng Xichuan, Luo Guibin, Di Guihua, and Ju Lei. This standard is not equivalent to the Japanese Industrial Standard JISK6506--77 "Industrial Basic Chromium Sulfate Test Method" and the specifications of Japan Co., Ltd.8 The rounded value comparison method specified in GB1250 shall be used to determine whether the test results comply with this standard. 7 Marking, packaging, transportation, storage
7.1 The packaging bags of industrial basic chromium sulfate should have firm and clear markings, including: manufacturer name, address, product name, trademark, category, net weight, batch number or production date and this standard number, as well as the "heat-afraid" mark and "moisture-afraid" mark in GB191. 7.2 Industrial basic chromium sulfate can be packaged in polypropylene woven bags lined with plastic bags, and the inner packaging is polyethylene plastic film bags, with specifications and dimensions: 1000mm×650mm , thickness is not less than 0.08mm, outer packaging uses polypropylene woven bags, specification size: 950mm×600mm, thickness 0.5mm.
When packaging, industrial basic chromium sulfate is put into a polypropylene woven bag lined with a polyethylene plastic film bag, and the remaining air in the bag is discharged. The inner bag is tied twice with a string and tied tightly. The outer bag is sewed with a bag sewing machine at a distance of not less than 17mm from the upper end of the bag, with a stitch length of 6~7mm, neat stitches, and uniform stitch length. There is no leakage or skipping. This product The net weight of each bag is 25kg. 7.3 Industrial basic chromium sulfate should be covered during transportation to prevent sun exposure, rain, and packaging damage. 7.4 Industrial basic chromium sulfate should be stored in a ventilated, dry warehouse to prevent sun exposure and moisture. 571
Additional instructions:
HG/T2678-95
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 Tianjin Chemical Industry Research Institute of the Ministry of Chemical Industry. This standard is under the jurisdiction of the Tianjin Chemical Industry Research Institute of the Ministry of Chemical Industry. The Tianjin Chemical Industry Research Institute, Zhangjiagang Xingda Chemical Factory, Jinan Yuxing Chemical Factory, Chongqing Dongfeng Chemical Factory, Changsha Chromium Salt Factory Gaoling Branch, Hubei Huangshi Inorganic Salt Factory, Qinghai Chromium Salt Factory, and Shanghai Chemical Light Industry Corporation were responsible for drafting. The main drafters of this standard are Liu Shuying, Zou Zhenqiu, Xu Zhuoliang, Wang Zhaolu, Du Jian, Cheng Xichuan, Luo Guibin, Di Guihua, and Ju Lei. This standard is not equivalent to the Japanese Industrial Standard JISK6506--77 "Industrial Basic Chromium Sulfate Test Method" and the specifications of Japan Co., Ltd.
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