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Chemical Industry Standard of the People's Republic of China
HG2324—92
Industrial Potassium Dichromate
Published on June 1, 1992
Ministry of Chemical Industry of the People's Republic of China
Implemented on September 1, 1992
WChemical Industry Standard of the People's Republic of China
Industrial Potassium Dichromate
Subject Content and Scope of Application
HG2324—92
This standard specifies the technical requirements, test methods, inspection rules, and marking, packaging, transportation, storage and safety requirements for industrial potassium dichromate.
This standard applies to industrial potassium dichromate (also known as potassium dichromate) prepared by double decomposition reaction using sodium dichromate and potassium chloride as raw materials. This product is mainly used in industries such as matches, chromium trioxide, potassium chrome yellow pigment, medicine, oxidants, pond porcelain, welding rods and potassium chromium sulfate. Molecular formula: K2Cr20m
Relative molecular mass: 294.18 (according to the international relative atomic weight in 1989) Reference standards
GB6284
GB6678
GB6682
Dangerous goods packaging mark
Packaging storage and transportation pictorial mark
Preparation of standard solution for titration analysis (volume analysis) of chemical reagents Preparation of standard solution for impurity determination
Chemical Chemical reagents
Preparation of preparations and products used in test methodsChemical reagents
General method for determination of moisture content in chemical productsGravimetric methodGeneral rules for sampling of chemical products
Specifications for laboratory water
Shaanxi DB61-49-91
Safety requirements for high-strength composite bags
3 Technical requirements
3.1 Appearance: orange-red crystals
3.2 Industrial potassium dichromate should meet the requirements of the following table:% (m/m)
Potassium dichromate (KzCr20z) content
Chloride (as CI) content
Water-insoluble matter content
Sulfate (as SO) content
Approved by the Ministry of Chemical Industry of the People's Republic of China on June 1, 1992 as superior product
Qualified product
Implemented on September 1, 1992
W.bzsoso:com4Test method
HG2324-92
The reagents and water used in this standard, unless otherwise specified, refer to analytical pure reagents and grade 3 water specified in GB6682. The standard solutions, impurity standard solutions, preparations and products required in the test, unless otherwise specified, are prepared in accordance with the provisions of GB601, GB602 and GB603.
4.1 Determination of potassium dichromate content
4.1.1 Method summary
In an acidic medium, the dichromate in the sample undergoes an oxidation-reduction reaction with the divalent iron ion, and o-phenylaminobenzoic acid is used as an indicator and directly titrated with ammonium ferrous sulfate standard titration solution. 4.1.2 Reagents and materials
4.1.2.1 Sulfuric acid (GB625) solution: 1+4; 4.1.2.2 Sulfuric acid (GB625) solution: 1+8; 4.1.2.3 Phosphoric acid (GB1282);
4.1.2.4 Anhydrous sodium carbonate (GB639) solution: 2g/L; 4.1.2.5 o-phenylaminobenzoic acid: 1g/L solution. Weigh 0.1g o-phenylaminobenzoic acid and dissolve it in 100mL sodium carbonate solution; (K2Cr20r) is about 0.15mol/L.
4.1.2.6 Potassium dichromate (GB1259) standard solution: c (Preparation: weigh about 7.5g of standard potassium dichromate dried to constant weight at 105-110℃, accurate to 0.0002g, dissolve in a 1000mL volumetric flask with water, dilute to the scale, and shake well. The concentration (c1) of the potassium dichromate standard solution is calculated according to formula (1): mV
KCr20)
Where: m——the mass of the weighed standard potassium dichromate, g; 49.03——the molar mass of potassium dichromate (K.Cr:0), g/mol; V——the volume of the volumetric flask, L.
4.1.2.7 Ammonium ferrous sulfate (GB661) standard titration solution: c[Fe(NH4)2(SO4)2) is about 0.2mol/L. (1)
Preparation: Weigh 80g of ammonium ferrous sulfate [Fe(NH) (SO) z·6HzO), dissolve it in 300mL of sulfuric acid solution (4.1.2.2), add 700mL of water, shake well, and calibrate the solution before use. Calibration: Use a pipette to transfer 50mL of potassium dichromate standard solution into a 500mL conical flask, add 150mL of water, 15mL of sulfuric acid solution (4.1.2.1), and 5mL of phosphoric acid, and titrate with ammonium ferrous sulfate standard titration solution until the solution turns yellow-green, then add 2mL of o-phenylaminobenzoic acid solution and continue titrating until the purple-red color turns to green. The concentration of the standard titration solution of ammonium ferrous sulfate (c) is calculated according to formula (2): V,·ci
Wherein: V1——volume of potassium dichromate standard solution; mL; Ci——actual concentration of potassium dichromate standard solution, mol/L; V.
volume of ammonium ferrous sulfate solution to be calibrated consumed in titration, mL. 4.1.3 Analysis steps
Weigh 5.0g of the sample, accurate to 0.0002g, place it in a 150mL beaker, add water to dissolve, transfer all of it into a 500mL volumetric flask 2
WHG2324-92
, dilute to the mark, and shake well. This test solution is also used for sulfate content determination. Use a pipette to transfer 25 mL of the test solution into a 500 mL conical flask, add 150 mL of water, 15 mL of sulfuric acid solution (4.1.2.1), and 5 mL of phosphoric acid, and titrate with ammonium ferrous sulfate standard titration solution until the solution turns yellow-green. Then add 2 mL of o-phenylaminobenzoic acid solution and continue titrating until the purple-red color turns to green. 4.1.4 Expression of analysis results
The content of potassium dichromate (K2Cr20) expressed as mass percentage (X1) is calculated according to formula (3): X,
V·cX0.04903
98.06V·c
Wherein: V—volume of standard ammonium ferrous sulfate solution consumed in titrating the test solution, mL; c——actual concentration of standard ammonium ferrous sulfate solution, mol/Lm
mass of sample, g;
0.04903——mass of potassium dichromate equivalent to 1.00mL standard ammonium ferrous sulfate solution c[Fe(NH)2(SO)21.000mol/L, expressed in grams.
4.1.5 Allowable error
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 chloride content
4.2.1 Method summary
In a slightly alkaline medium, the chloride ions in the sample and the silver ions quantitatively form a precipitate, and the formation of a brick-red precipitate of silver chromate indicates the end point.
4.2.2 Reagents and materials
4.2.2.1 Saturated solution of anhydrous sodium carbonate (GB639); 4.2.2.2 Standard titration solution of silver nitrate (GB670): c (AgNOs) is about 0.05 mol/L. Preparation: Use a pipette to transfer 50 mL of the standard titration solution of silver nitrate prepared according to GB601, place it in a 100 mL volumetric flask, dilute it to the scale with water, and shake it well;
4.2.2.3 Potassium dichromate (GB642): high-grade pure. 4.2.3 Instruments and equipment
4.2.3.1 Microburette: the graduation value is 0.02mL or 0.01mL. 4.2.4 Analysis steps
Weigh 3.00g of sample, place it in a 250mL conical flask, add 50mL of water to dissolve, carefully add sodium carbonate solution until the solution turns yellow, at which point the pH is 7.5-8.0 (check with precision pH test paper), then titrate with silver nitrate standard titration solution until the solution turns slightly brick red as the end point.
Weigh 3.00g of potassium dichromate (4.2.2.3) for comparison test. When there is no change in the reagent and water, only one comparison test can be performed. 4.2.5 Expression of analytical results bZxz.net
The chloride content (in terms of Cl) expressed as mass percentage (X,) is calculated according to formula (4): X2 = -Vo) ·c× 0. 035 45
_3.545 Xc (V -Vo)
WHG2324-92
c——actual concentration of the standard silver nitrate solution, mol/L; m——mass of the sample, g;
0.03545——the mass of the sample with respect to 1.00mL silver nitrate standard titration solution [c (AgNOs) = 1.000mol/L], the mass of chloride (in terms of CI) expressed in grams.
4.2.6 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result, and the absolute difference of the parallel determination results shall not exceed 0.0005%. 4.3 Determination of water-insoluble matter content
4.3.1 Method summary
After dissolving the sample in boiling water, filter and wash it, and measure the mass of the dried filter residue. 4.3.2 Instruments and equipment
4.3.2.1 Filter: The filter plate has a pore size of 5~15μm. 4.3.3 Analysis steps
Weigh about 50g of sample, accurate to 0.01g, place in a 400mL beaker, add 200mL of water, cover with a watch glass, heat to boiling, keep warm in a boiling water bath for 1h, filter with a crucible filter that has been dried to constant weight at 105-110℃, wash with hot water until the filter plate is colorless, and bake the crucible filter together with the water-insoluble matter at 105-110℃ to constant weight. 4.3.4 Expression of analysis results
The water-insoluble matter content (X3) expressed as mass percentage is calculated according to formula (5): Xg=m2=m1×100
Where: m1—mass of the crucible filter, g; m2—mass of the crucible filter and water-insoluble matter after drying, 8; m—mass of the sample, g.
4.3.5 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result, and the absolute difference of the parallel determination results shall not exceed 0.0005%. 4.4 Determination of sulfate content
4.4.1 Method summary
In the hydrochloric acid medium, sulfate ions and barium ions generate white fine barium sulfate precipitates, which are turbid with the standard solution. 4.4.2 Reagents and materials
4.4.2.1 Hydrochloric acid (GB622) solution: 1+11; 4.4.2.2 Barium chloride (GB625) solution: 100g/L; 4.4.2.3 Potassium dichromate (GB642, high-grade pure) solution: 10g/L solution; 4.4.2.4 Sulfate standard solution: 0.050mgSOz/mL. (5)
Use a pipette to transfer 50 mL of the sulfate standard solution prepared according to GB602 into a 100 mL volumetric flask, dilute to the mark with water, and shake well.
4.4.3 Instruments and equipment
4.4.3.1 Colorimetric tube: 50 mL
4.4.4 Analysis steps
Use a pipette to transfer 25 mL of the test solution prepared in 4.1.3 (equivalent to 0.25 g of the sample) into a colorimetric tube, use a pipette to transfer 10 mL of the sulfate standard solution, then add 5 mL of hydrochloric acid solution and 5 mL of barium chloride solution, dilute to 50 mL with water, shake well, and place in a water bath at 30-40°C for 20-30 min. The turbidity shall not be greater than the standard. Preparation of standard turbidity solution: Use a pipette to transfer sulfate standard solution 4
W superior product: 2.0mL;
first-class product: 3.5mL.
HG2324-92
Put them in two colorimetric tubes respectively, add 25mL potassium dichromate solution (4.4.2.3) to each, and treat them in the same way as the test solution starting from "add 5mL hydrochloric acid solution". 4.5 Determination of moisture
4.5.1 Instruments and equipment
4.5.1.1 Weighing bottle: diameter @50mm, height h30mm. 4.5.2 Analysis steps
Use a weighing bottle that has been dried to constant weight at 105~110℃ in advance to weigh about 10g of sample, accurate to 0.0002g, and dry at 105~110℃ to constant weight.
4.5.3 Expression of analysis results
The moisture content (X,) expressed as a percentage by mass is calculated according to formula (6): X = m = m × 100
Where: m—mass of the sample, g;
—mass of the sample after drying, 8.
4.5.4 Allowable difference
The arithmetic mean of the equal determination results is taken as the determination result, and the absolute difference of the parallel determination results shall not exceed 0.0005%. 5 Inspection rules
·· (6)
5.1 Industrial potassium dichromate 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 industrial potassium dichromate 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 shall include: manufacturer name, product name, grade, batch number, net weight, production date, proof that the product quality meets this standard and the number of this standard. 5.2 The user has the right to inspect and accept the industrial potassium dichromate received in accordance with the provisions of this standard. 5.3 Each batch of products shall not exceed 5t
5.4 The number of sampling units shall be determined in accordance with Article 66 of GB6678. When sampling, insert the sampler vertically from the center of the packaging barrel or bag to 3/4 of the depth of the material layer. Mix the collected samples, reduce them to about 500g by quartering, and pack them in two clean and dry bottles, seal them, and stick labels on the bottles, indicating: manufacturer name, product name, grade, batch number, sampling date and name of the sampler. One bottle is used for inspection and the other bottle is kept for three months. 5.5 If one indicator of the inspection result does not meet the requirements of this standard, re-sampling and inspection should be carried out from the packaging of twice the number of sampling units. Even if only 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". 6 Marking, packaging, transportation, storage
6.1 Industrial potassium dichromate packaging barrels or bags 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 mark 11 "oxidant" mark and mark 14 "toxic" mark as specified in GB190. The iron barrel should also have mark 3 "upward" mark as specified in GB191. 6.2 Industrial potassium dichromate can be packaged in iron barrels or high-strength composite bags (in accordance with Shaanxi DB61-46-91 regulations). The iron barrel packaging adopts double-layer packaging, the inner packaging adopts polyethylene plastic film bags with a film thickness of 0.08-0.1mm, and the outer packaging adopts a special sealed, fully open iron barrel with an iron sheet thickness of 0.5-0.75mm. The specifications and dimensions of packaging barrels of different specifications and their inner plastic film bags are determined according to the net weight of the product. Put industrial potassium dichromate into a special sealed fully open iron barrel lined with a layer of polyethylene plastic film bag, remove the remaining gas in the bag, tie it tightly with a rope, cover the barrel lid and seal it. The net weight of each barrel of industrial potassium dichromate is 50kg or 100kg. 5
W.bzsosO.coI HG2324—92
High-strength composite bag packaging adopts three-layer packaging, the inner packaging adopts two layers of polyethylene plastic film bags, the specification size is: 930mm×530mm, the thickness is not less than 0.05mm, and the outer packaging adopts high-strength composite bags, the specification size is: 830mm×480mm. When using high-strength composite bags for packaging, industrial potassium dichromate is placed in a high-strength composite bag lined with a two-layer polyethylene plastic film bag, the residual air in the bag is exhausted, the bag mouth is tied up with a string, and the outer bag is sewed at a distance of not less than 17mm from the bag edge with a special high-strength sewing thread, with a stitch length of 12-14mm, neat stitches, uniform stitch length, and no leaking or skipping stitches. After sewing, use a "V"-shaped adhesive tape to seal the edge. The net weight of each bag of industrial potassium dichromate is 40kg. 6.3 Industrial potassium dichromate should be covered during transportation. During transportation, attention should be paid to moisture-proof, heat-proof, shock-proof, and away from flammable materials. The high-strength composite bag containing the product must not be contaminated during transportation, and must not collide with sharp devices or hook. 6.4 Industrial potassium dichromate should be stored in a ventilated and dry warehouse, and attention should be paid to moisture-proof, heat-proof, shock-proof, and away from flammable materials. During the storage and use of high-strength composite bags, the surface of the bag must not be contaminated, and it must not collide with sharp devices or hook. 7 Safety requirements
7.1 Industrial potassium dichromate is a strong oxidant. When it comes into contact with organic matter or flammable materials, it will cause combustion and explosion. 7.2 Industrial potassium dichromate is toxic. When the concentration of potassium dichromate in the air exceeds the allowable concentration, it will cause nasal mucosal ulceration. Potassium dichromate solution and powder will irritate the skin, eyes and nasal mucosa. When the broken skin comes into contact with it, it will cause ulcers that are difficult to heal. When the eyes are contaminated, it will cause conjunctivitis and even blindness. Inhalation of potassium dichromate into the body will cause severe poisoning. 7.3. All workers who come into contact with potassium dichromate must abide by the following rules: Before work, they must wear work clothes that meet standard specifications, must use personal protective masks, and when working in the production workshop, they must pay close attention to whether the ventilation device is intact: abide by personal hygiene rules, must shower after work, and apply ointment to the broken skin for protection.
Additional instructions:
This standard was proposed by the Science and Technology Department of the Ministry of Chemical Industry of the People's Republic of China. This standard was drafted by Jinan Yuxing Chemical Plant and Tianjin Chemical Research Institute of the Ministry of Chemical Industry. The main drafters of this standard are Wang Zhaolu, Qu Xiujun and Zhang Jingjuan. This standard refers to the Soviet national standard IOCT2652-78 "Technical Conditions for Industrial Potassium Dichromate" (revised in 1984). From the date of implementation of this standard, the original national standard of the People's Republic of China GB160979 "Potassium Dichromate" will be invalid. o
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