Some standard content:
Chemical Industry Standard of the People's Republic of China
Industrial Sulfuric Acid to
1 Subject Content and Scope of Application
HG/T 2570--94
This standard specifies the technical requirements, test methods, inspection rules and marking, packaging, transportation and storage of industrial potassium chromium sulfate. This standard applies to industrial potassium chromium sulfate, also known as chromium alum, which is obtained by acidification of potassium dichromate with sulfuric acid and reduction of organic matter. This product is mainly used in dyes, leather and oil drilling, etc.
Molecular formula: KCr(SO.)2·12H,0
Relative molecular mass: 499.41 (according to the international relative atomic mass in 1989) 2 Reference standards
GB 191
Pictorial symbols for packaging, storage and transportation
GB/T 601
GB/T 602
GB/T 603
Preparation of standard solutions for titration analysis (volume analysis) of chemical reagents Preparation of standard solutions for determination of impurities of chemical reagents Preparation of preparations and products used in test methods for chemical reagents Methods for expressing and determining limit values GB1250
GB/T6678 General rules for sampling of chemical products
GB/T 6682
3 Technical requirements
Specifications and test methods for water used in analytical laboratories 3.1 Appearance: purple-red crystals. wwW.bzxz.Net
3.2 Industrial potassium chromium sulfate shall meet the requirements of the following table. (m/m)
Potassium chromium sulfate TKCr(S,)z12H2O) content
Iron (Fe) content
Test method
Superior quality
First-class quality
Qualified quality
The reagents and water used in this standard, unless otherwise specified, refer to analytical reagents and grade 3 water specified in GB/T6682. The standard titration solutions, impurity standard solutions, preparations and products used in the test, unless otherwise specified, shall be prepared in accordance with the provisions of GB/T601GB/T602.GB/T603.
Grind the sample in a mortar.
4.1 Determination of potassium chromium sulfate content
Approved by the Ministry of Chemical Industry of the People's Republic of China on February 9, 1994. 550
Implementation on July 1, 1994
4.1.1 Summary of method
HG/T 2570-94
The trivalent chromium in the sample is oxidized to hexavalent chromium with hydrogen peroxide and reacted with potassium iodide in an acidic medium. The precipitated iodine is titrated with a standard sodium thiosulfate solution and starch is used as an indicator to indicate the end point. 4.1.2 Reagents and materials
4.1.2.1 Sulfuric acid (GB/T625) solution: 1+8; 4.1.2.2 Sodium chloride oxide (GB/T629) solution: 100g/L, 4.1.2.3 Hydrogen peroxide (GB/T2300) solution: 30%, 4.1.2.4 Potassium iodide (GB/T1272);
4.1.2.5 Soluble starch: 5g/L solution; weigh 0.5g starch, add 5mL water to make a paste, and add it to 95mL boiling water under stirring.
4.1.2.6 Sodium thiosulfate (GB/T637): c(Na2S2O,) is about 0.1mol/L standard titration solution. 4.1.3 Analysis steps
Weigh 0.5g sample (accurate to 0.0002g), place in a 500mL iodine volume flask, add 20mL water, dissolve the sample, add 5mL sodium hydroxide solution, 1mL hydrogen peroxide solution, heat to boil; remove excess hydrogen peroxide, cool to room temperature, add 20mL water, 2g potassium iodide, 10ml sulfuric acid solution, place in a dark place for 10min, add 150mL water, titrate with sodium thiosulfate standard titration solution until the solution turns grass green, add 3mL starch solution, and continue to titrate until the solution turns bright green as the end point. The same operating procedure as the analysis of the sample, add the same amount of reagent, but do not add the sample, and perform a blank test. 4.1.4 Expression of analytical results
The content of potassium chromium sulfate (CKCr(SO4)2·12H,O) expressed as mass percentage is calculated according to formula (1): (VV.) .cX. 166 5×100 .
Wherein: V is the volume of sodium thiosulfate standard titration solution consumed by titrating the test solution, mL; V. --- the volume of sodium thiosulfate standard titration solution consumed by titrating the blank solution, mL; the actual concentration of sodium thiosulfate standard titration solution, mol/L, m --- the mass of the sample, g
(1)
is the mass of potassium chromium sulfate expressed in grams equivalent to 1.00 mL of sodium thiosulfate standard titration solution [c(NazS,0.)=1.000 mol/L].
4.1.5 Allowable difference
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 0.2%. 4.2 Determination of iron content
4.2.1 Method summary
In an acidic medium, potassium permanganate is used to oxidize divalent iron ions to trivalent iron ions, and potassium thiocyanate-butanol solution is added to generate a red ferric thiocyanate complex for colorimetry.
4.2.2 Reagents and materials
4.2.2.1 Hydrochloric acid (GB/T622) solution: 1+5; 4.2.2.2 Potassium permanganate (GB/T643) solution: 1g/L; 4.2.2.3 Potassium thiocyanate (GB/T648)-butanol (HG/T3-1012) solution: Dissolve 10g potassium thiocyanate in 10mL water, add 90ml n-butanol, and shake vigorously.
4.2.2.4 Iron standard solution: 1ml. Contains 0.01mg iron.
Use a pipette to transfer 10mL of the iron standard solution prepared according to GB/T602, place it in a 100mL volumetric flask, dilute it with water to the mark, shake it. 4.2.3 Analysis steps
Weigh 1g of the sample (accurate to 0.01g), place it in a 250mL beaker, add 18mL of hydrochloric acid solution, boil it for 2min, cool it, transfer it to a 551
HG/T 2570-94
1010ml. volumetric flask, dilute it with water to the mark, and shake it. Use a pipette to transfer 5ml, place it in a 50mL colorimetric tube, add 15ml of water, drop potassium manganate solution until it turns pink, add 15ml. potassium thiocarbamide butanol solution, dilute it with water to the mark, shake it for 1min, and the color of the butanol layer should not be darker than the standard colorimetric solution.
The standard colorimetric solution is 2ml (superior product), 6ml (minus product) or 7.5mL (qualified product) of iron standard solution, placed in a 50ml colorimetric tube, and treated in the same way as the test solution starting from "add 15ml water". 5 Inspection rules
5.1 Industrial potassium chromium sulfate should be inspected by the quality supervision and inspection department of the manufacturer in accordance with the provisions of this standard. The manufacturer should ensure that all industrial potassium chromium sulfate products shipped meet the requirements of this standard. Each batch of products shipped should be accompanied by a quality certificate. The content includes the manufacturer's name, address, product name, grade, net weight, batch number or production date, proof that the product quality meets this standard and the standard number. 5.2 The user has the right to accept the industrial potassium chromium sulfate received in accordance with the provisions of this standard. 5.3 The batch of products shall not exceed 5t.
5.4 Determine the number of sampling units in accordance with the provisions of Article 6.6 of GB/T6678. Each barrel or each high-strength composite bag is a packaging unit. 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 to take a sample. From each selected packaging unit, take out no less than 50g of sample, mix the sampled sample and reduce it to about 500g by quartering, and immediately put it into two clean, dry and wide-mouth bottles with ground stoppers and seal them. Attach labels to the bottles, indicating the manufacturer's 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 for reference. 5.5 If any of the indicators in the inspection results do not meet the requirements of this standard, re-sampling should be carried out from twice the number of sampling units. Even if only one of the inspection results is found to be unsatisfactory, the sample should be re-sampled and verified. If the indicators do 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 "Product Quality Law of the People's Republic of China". 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 Industrial potassium chromium sulfate packaging barrels or bags should have firm and clear markings, including the manufacturer's name, address, product name, trademark, grade, net weight, batch number or production date and this standard number, and the moisture-proof mark specified in GB191. 6.21 Industrial potassium chromium sulfate can be packaged in iron barrels lined with plastic bags, or in high-strength composite bags. Iron barrel packaging: The inner packaging uses a polyethylene plastic film bag with specifications and dimensions: 900mm×550mm, and the thickness is not less than 0.08mm, the outer packaging adopts a sealed fully open iron barrel, the specification size is: 390mm×500mm, the thickness is 0.5mm. When using iron barrel packaging, put the industrial potassium chromium sulfate into the iron barrel lined with polyethylene plastic bags, discharge the remaining gas in the bag, tie the bag mouth with a string, cover the barrel lid and seal it. The net weight of each barrel of this product is 50kg. The high-strength composite bag packaging adopts three-layer packaging, the inner packaging adopts two layers of polyethylene plastic film bags, the specification size is: 870mm×500mm, the thickness is not less than 0.05mm, and the outer packaging adopts a high-strength composite bag, the specification size is: 800mm×450mm. During packaging, industrial potassium chromium sulfate is placed in a high-strength composite bag lined with two layers of polyethylene plastic film bags, the remaining air in the bag is discharged, the bag mouth is tied up with a string or sealed with other equivalent methods, and the outer bag is sewed with special high-strength sewing thread at a distance of not less than 17mm from the bag edge, with a stitch length of 7~12mm, neat stitches, uniform stitch length, and no leaking or skipping stitches. The seams are sealed in a "V" shape with a paper strip for binding, and the net weight of each bag of this product is 40kg. 6.31 Industrial potassium chromium sulfate should be covered during transportation to prevent sun exposure, rain, and packaging damage. 6.4L Industrial potassium chromium sulfate should be stored in a ventilated and dry warehouse to prevent sun exposure and moisture. 5
Additional instructions:
HG/T2570-94
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 Tianjin Chemical Research Institute of the Ministry of Chemical Industry. This standard was drafted by Tianjin Chemical Research Institute of the Ministry of Chemical Industry and Tianjin Tongsheng Chemical Factory. The main drafters of this standard are Xiao Naiping, Li Dahua and Zhang Jingjuan. This standard adopts the specifications of ANSI PH4.151-1986 "Photographic Grade Potassium Chromium Sulfate". 5.53
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