Some standard content:
Chemical Industry Standard of the People's Republic of China
HG/T2498-93
Sodium hypochlorite solution
Published on September 8, 1993
Ministry of Chemical Industry of the People's Republic of China
Implemented on October 1, 1994
W Chemical Industry Standard of the People's Republic of China
Sodium hypochlorite solution
Subject content and scope of application
HG/T2498-93
Replaces HG/T1-1137-78
This standard specifies the technical requirements, test methods, inspection rules and marking, packaging, transportation and storage of sodium hypochlorite solution. This standard applies to sodium hypochlorite solution prepared by chlorination of sodium hydroxide. 2 Reference standards
GB/T601
GB/T602
GB/T603
GB/T3049
GB/T6682
Chemical reagents Preparation of standard solutions for titration analysis (volume analysis) Chemical reagents
Preparation of standard solutions for impurity titration
Chemical reagents
Preparation of preparations and products used in test methods General method for determination of iron content in chemical products O-phenanthroline spectrophotometric method Specifications and test methods for laboratory water GB8170 Numerical rounding rules
3 Technical requirements
3.1 Appearance: light yellow liquid.
3.2 Sodium hypochlorite solution should meet the requirements in the following table. Item
Available chlorine content (calculated as C1), %
Free alkali content (calculated as NaOH), %
Iron content, %
Test method
The test water shall comply with the third-grade water specification in GB/T6682. 4.1 Determination of available chlorine content
4.1.1 Principle
In an acidic medium, hypochlorite reacts with potassium iodide to precipitate iodine, and starch is used as an indicator to titrate with a sodium thiosulfate standard titration solution until the blue color of the solution disappears. The reaction formula is as follows: 2H++OCI-+2I-I2+C1-+H20
I2+2S20S,+21
4.1.2 Instruments and equipment
General laboratory instruments
4.1.3 Reagents and solutions
Approved by the Ministry of Chemical Industry of the People's Republic of China on September 8, 1993 and implemented on October 1, 1994
W.4.1.3.1 Hydrochloric acid (GB/T622): 1+1 solution; HG/ T2498—93
4.1.3.2 Potassium iodide (GB/T1272): 100g/L, weigh 100g potassium iodide and dissolve it in water, dilute to 1000mL and shake well; 4.1.3.3 Sodium thiosulfate (GB/T637) standard titration solution: c(Na2S20:) = 0.1mol/L, prepared and calibrated according to GB/T601; 4.1.3.4 Starch solution (HGB3095): 10g/L, prepared according to GB/T603. This solution is prepared before use. 4.1.4 Sample and its preparation
Take 20mL of sample (5.4), place it in a 100mL beaker containing 20mL of water and weighed (accurate to 0.01g), weigh (accurate to 0.01g) and then transfer all of it into a 500mL volumetric flask, dilute to the scale with water, and shake well. 4.1.5 Analysis steps
Pipette 10.0 mL of the sample (4.1.4) and place it in a 250 mL iodine volumetric flask filled with 50 mL of water. Add 4 mL of hydrochloric acid solution (4.1.3.1), quickly add 10 mL of potassium iodide solution (4.1.3.2), cover the bottle tightly with a stopper and seal with water. After standing in a dark place for 5 min, titrate with sodium thiosulfate standard titration solution (4.1.3.3) until it turns light yellow. Add 2 mL of starch solution (4.1.3.4) and continue titrating until the blue color disappears, which is the end point. 4.1.6 Calculation of analysis results
The effective chlorine content (X1) is expressed as a mass percentage and is calculated according to formula (1): Xi = oV· 0.03545×100 = 177.250·V.100
Wherein: c——actual concentration of sodium thiosulfate standard titration solution (4.1.3.3), mol/L; V——amount of sodium thiosulfate standard titration solution (4.1.3.3), mL; m——mass of sample (4.1.4), g;
0.03545——mass of effective chlorine equivalent to 1.00mL sodium thiosulfate standard titration solution Lc(Na2S,0s)=1.000mol/L) expressed in grams.
Take the arithmetic mean of the results of two parallel determinations as the reported result. 4.1.7 Allowable difference
The absolute difference between the results of two parallel determinations shall not exceed 0.1%. 4.2 Determination of free alkali content
4.2.1 Principle
In a medium without hypochlorite, use phenolphthalein as an indicator and titrate with a standard hydrochloric acid solution until a slightly pink color is reached. The reaction formula is as follows,
OC1-+H202-C1=+02+H20
OH-+H+-H20
4.2.2 Instruments and equipment
General laboratory instruments
4.2.3 Reagents and solutions
4.2.3.1 Hydrogen peroxide (GB/T6684);
4.2.3.2 Hydrochloric acid (GB/T622) standard titration solution: c(HCI)=0.1000mol/L, prepared and calibrated according to GB/T601; 4.2.3.3 Phenol: 10g/L, prepared according to GB/T604. 4.2.4 Analysis steps
Pipette 50.0 mL of the sample (4.1.4) and place it in a 250 mL conical flask. Add hydrogen peroxide (4.2.3.1) dropwise until the solution stops bubbling. Add 2 to 3 drops of phenolic acid (4.2.3.3) and titrate with standard hydrochloric acid solution (4.2.3.2) until it turns slightly pink. 4.2.5 Calculation of analysis results
The free alkali content (X2) is expressed as a percentage by mass and is calculated according to formula (2): X2-CV0.04
HG/T2498-93
Wherein: c——actual concentration of hydrochloric acid standard titration solution (4.2.3.2), mol/LV—amount of hydrochloric acid standard titration solution (4.2.3.2), mL; m——mass of sample (4.1.4), g;
0.04The mass of sodium hydroxide expressed in grams equivalent to 1.000mL hydrochloric acid standard titration solution [c (HC) = 1.000mol/L] The arithmetic mean of the results of two parallel determinations is taken as the reported result. 4.2.6 Allowable difference
The absolute difference of the results of two parallel determinations shall not exceed 0.04%. 4.3 Determination of iron content
4.3.1 Principle
In a medium without hypochlorite, ascorbic acid is used to reduce the ferric iron in the solution to ferrous iron. In a pH 4-4.5 buffer solution system, the ferrous iron ions react with o-phenanthroline to form an orange-red complex, which is determined by spectrophotometry. The reaction formula is as follows: 2Fe3+CgHgO62Fe2++CgHgOg+2H2+2Fe2++2C12HgN2(Fe(C12HgN2)J2+4.3.2 Instruments and equipment
General laboratory instruments
4.3.3 Reagents and solutions
4.3.3.1 Hydrogen peroxide (GB/T6684);
4.3.3.2 Hydrochloric acid (GB/T622): 0.1mol/L, prepared according to GB/T601; 4.3.3.3 Iron standard solution: 1mL solution contains 0.1mg iron, prepared according to GB/T602; 4.3.3.4 Iron standard solution: 1mL solution contains 0.01mg iron, take (4.3.3.3) solution and dilute it 10 times, the solution is prepared before use; 4.3 .3.5 Acetic acid (GB/T676)-sodium acetate (GB/T694) buffer solution: pH~4.5, prepared according to GB/T603; 4.3.3.6 Ascorbic acid: 20g/L, prepared according to GB/T603; 4.3.3.7 Phenanthroline (GB/T1293): 2g/L, prepared according to GB/T603. 4.3.4 Drawing of standard curve
4.3.4.1 Determination of absorbance of standard reference solution Take 0.0, 1.0, 2.0, 3.0, 4.0, 6.0, 8.0, 10.0mL of iron standard solution (4.3.3.4) in a 100mL volumetric flask, then add 2.5mL of ascorbic acid (4.3.3.6), 10mL of buffer solution (4.3.3.5), 5mL of o-phenanthroline (4.3.3.7) Dilute with water to the scale and shake well. Adjust the absorbance of the instrument to zero with the reference solution without adding the iron standard solution. At a wavelength of 510nm, select a suitable absorption cell to measure the absorbance of the standard reference solution.
4.3.4.2 Drawing of the standard curve
Draw the standard curve with the milligrams of iron contained in the standard reference solution as the horizontal axis and the corresponding absorbance as the vertical axis. 4.3.5 Analysis steps
4.3.5.1 Determination of sample absorbance
Put 50.0mL of sample (4.1.4) in a 100mL volumetric flask, add 10mL of water, drop hydrogen peroxide solution (4.3.3.1) until no bubbles appear, then add 2.5mL of ascorbic acid solution (4.3.3.6), 10mL of buffer solution (4.3.3.5), 5mL of o-phenanthroline solution (4.3.3.7), dilute to scale with water, and shake well. Let stand for 20 minutes, adjust the instrument absorbance to zero with blank solution without sample, and then measure the sample absorbance.
4.3.5.2 Calculation of analysis results
Find the iron content mg corresponding to the sample absorbance from the standard curve. The iron content (X?) is expressed as a percentage by mass and is calculated according to formula (3): 1
m11000
×100=
HG/T2498-93
Wherein: m1——iron content corresponding to the sample absorbance, mg; m——mass of the sample (4.1.4), g.
Take the arithmetic mean of the results of two parallel determinations as the reported result. 4.3.5.3 Allowable difference
The absolute difference between the results of two parallel determinations shall not exceed 0.001%. 5 Inspection rules
5.1 The inspection results of this standard are determined by the rounding value comparison method, and data processing is carried out in accordance with GB8170. 5.2 The sodium hypochlorite solution leaving the factory shall be inspected by the quality inspection department of the production unit. Each batch of products must meet the requirements of this standard and be accompanied by a quality certificate.
5.3 The user unit has the right to accept the received products in accordance with the provisions of this standard. 5.4 When sodium hypochlorite solution is shipped by tank truck or storage tank, take out equal amounts of samples from the top, middle and bottom and mix them evenly; when shipped by cans (barrels), 10% of the total number of samples should be sampled, but in case of small batches, no less than 3 cans (barrels) should be sampled. The sampling volume shall not be less than 500mL. Put the sampled sample into a clean, dry brown wide-mouth bottle with a ground stopper. The bottle should be marked with the name of the manufacturer, product name, batch number, sampling date and name of the sampler. 5.5 All technical indicators specified in this standard are type inspection items, among which the indicators of effective chlorine and free alkali content are factory inspection items. When production is normal, type inspection shall be carried out at least once a month. 5.6 If one of the indicators in the inspection results does not meet the requirements of this standard, samples should be taken from twice the number of packages for re-inspection. If one of the indicators in the re-inspection results does not meet the requirements of this standard, the entire batch of products shall be unqualified. 5.7 When the supply and demand parties have objections to the product quality, the quality supervision department shall arbitrate. 6 Marking, packaging, transportation and storagebzxZ.net
6.1 Marking
The name of the manufacturer, product name, trademark, specification, production batch number and net weight, etc. shall be marked on the packaging barrel (tank truck) of sodium hypochlorite solution. 6.2 Packaging
Sodium hypochlorite solution shall be packaged in plastic barrels or tank trucks. The user unit may prepare special packaging containers by itself, and the packaging shall carry weight instructions. 6.3 Transportation and storage
It shall be airtight during transportation, and the shipping container shall be corrosion-resistant. It shall be stored in a dry and light-proof shed. The effective chlorine content of type I of the product shall not be less than 11.0% and that of type II shall not be less than 8.0% within 3 days from the date of ex-factory.
Additional instructions:
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 technical jurisdiction of Jinxi Chemical Research Institute of the Ministry of Chemical Industry. This standard is drafted by Jinxi Chemical Research Institute of the Ministry of Chemical Industry. The main drafters of this standard are Wang Minjie and Guan Liping. This standard type I refers to the German standard DIN19608-76 "Industrial delivery conditions for sodium hypochlorite for water treatment" 4
W.
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