HG 3017-1988 Determination of chlorine content in chlorinated paraffins - Mercury titration method HG3017-1988 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determination of chlorine content in chlorinated paraffins
Mercurimetric method
Chlorinated paraffins-Determination of chlorine contentMercurimetric methodThis standard applies to the determination of chlorine content in chlorinated paraffin products. 1 Principle
UDC65.41:546.13www.bzxz.net
GB 1679-88
Replaces GB 1679-81
Burning the sample in oxygen, destroying its organic structure, the chlorine in the sample is converted into chloride ions. In a slightly acidic solution, the nitrogen ions are converted into ionized mercuric chloride using a strongly ionized nitric acid solution, and the end point is determined by using a diphenylazocarbonyl indicator to produce a purple-red complex with excess mercuric ions (H).
2 Reagents and solutions
When not specified, the reagents used are all analytical grade, and the water is all distilled water or water of corresponding purity. 2.1 Nitric acid (GB 626-78): 1:1 solution. 2.2 Hydrogen peroxide (HG3-1082-77): 30% solution. 2.3 Oxygen.
2.4 Bromophenol blue (HG 3-1224-79): 0.1% ethanol solution. 2.5 Potassium hydroxide (GB2306-80): 10g/L solution. 2.6 Benzene azocarbonyl cake: 0.5% ethanol solution. When the color change is not smooth, it should be re-prepared. 2.7 Sodium chloride (reference reagent): 0.05M standard solution. Preheat sodium chloride at 500-600℃ to constant weight, accurately weigh 2.922g (weighing to 0.001g) and place it in a beaker, add a small amount of water to dissolve, transfer all the solution into a 100)ml volumetric flask, add water to the scale, and shake the hook. 2.8 nitric acid multiplied by [HgNOg2.HzO]: 0.025M standard solution. 2.8.1 Preparation: Weigh 8.57 mercuric nitrate (2.8>) and place in a 250ml beaker, add 7ml nitric acid solution (2.1), add a small amount of water to dissolve, filter if necessary, transfer to a 1000ml volumetric flask, dilute to the mark with water, and shake. 2.8.2 Calibration: Accurately take 25ml sodium chloride standard solution (2.7), place in a 500ml conical flask, add 100ml water and 2-3 drops of bromophenol blue indicator, add nitric acid solution (2.1) until the solution changes from blue to yellow, add 1 drop in excess, add 1ml diphenylazocarbonyl indicator, and titrate with 0.025M nitric acid standard solution (2.8) until the solution changes from yellow to purple-red. The waste liquid after titration is stored in a container and handled according to Appendix A. Perform a blank test at the same time.
2. 8.3 The molar concentration of the standard solution of mercuric nitrate is calculated according to formula (1): M=
Wherein: M
The molar concentration of the standard solution of sodium chloride, Mi.Vi
2(VV)
The volume of the standard solution of sodium chloride, ml, V,
The volume of the standard solution of mercuric nitrate consumed in the titration, ml, V
Vo—The volume of the standard solution of mercuric nitrate consumed in the titration blank, ml. 3 Instruments and Equipment
3.1: General laboratory instruments and equipment.
Approved by the Ministry of Chemical Industry of the People's Republic of China on February 2, 1988: 131
Implemented on October 1, 1988
3.2 Flag filter paper: The shape is shown in Figure 1.
GB 1679-88
2u × 20
Figure 1 Flag filter paper
3.3 Combustion flask: 500ml standard ground flask, the shape is shown in Figure 2. Figure 2 Combustion flask
4 Operation steps
4.1 Preparation of test solution
Put the folded filter paper (3.2) into the spiral of platinum wire (or nickel-chromium wire) on the stopper of the combustion flask, weigh 0.03~0.05 (weighing to 0.0002g) of the sample in the filter paper by the reduction method, and put it in place so that the tail of the filter paper is exposed. 195
GB 1679—88
Add 20ml potassium hydroxide absorption liquid (2.5) to an empty combustion bottle (3.3), add 2 drops of hydrogen peroxide (2.2), and blow oxygen (2.3) at a medium flow rate on the liquid surface for about 30 seconds. Take the bottle, light the end of the filter paper on the alcohol lamp with a lance, quickly plug it tightly, and tilt the combustion bottle so that the liquid forms a liquid seal around the plug, place it in a safety cover, and shake it thoroughly to make it completely absorbed after it is completely burned. , leave for 5-10 minutes. Rinse the stopper with 100 ml of water, add the washing liquid into the combustion bottle 4, add 2-3 drops of bromophenol blue indicator (2.4), add nitric acid solution (2.1) until the color of the solution changes from blue to yellow, and then add 1 drop. 4.2 Titration
Add 1 ml of diphenylazocarbonyl hydrazide indicator (2.6) to the test solution (4.1), and titrate with 0.025M mercuric nitrate standard solution (2.8) until the color of the solution changes from yellow to purple-red. The waste liquid after titration is stored in a container and handled according to Appendix A. Perform a blank test at the same time.
5 Expression and calculation of results
5.1 The chlorine content (in terms of nitrogen) is calculated according to formula (2): V-Ve×M×35.45
Cl (%) = (2×
M (V-Vo) ×7.090
-the volume of the standard solution of mercuric nitrate consumed by the titration of the sample, ml, where:
-the volume of the standard solution of mercuric nitrate consumed by the titration of the blank, ml, M——the molar concentration of nitric acid to be calculated; the mass of the sample:
35.45——the original amount of chlorine.
5.2 The result is the arithmetic half mean of the two measured values. The difference between the two measured values ​​should not be greater than 0.5%. to
A Principle
GB 1679-88
Appendix A
Waste liquid treatment method
(Supplement)
Use excess sodium sulfide to precipitate mercury in alkaline solution, and use hydrogen peroxide to oxidize excess sodium sulfide to prevent mercury from dissolving in the form of polysulfide.
A2 operation steps
Collect the slurry in a container of about 50L. When the slurry reaches 40L, add 400ml of 40% sodium hydroxide solution and 100g of sodium sulfide (NazS-gHzO) in sequence. After 10 minutes, slowly add 400ml of 30% hydrogen peroxide solution, mix thoroughly, and after 24 hours, drain the upper clear liquid into the wastewater, transfer the precipitate into another container, and appoint a special person to be responsible for mercury recovery. The above reagents are all industrial grade.
Additional remarks:
This standard is under the jurisdiction of Shanxi Institute of Chemical Industry. This standard was drafted by Shanxi Institute of Chemical Industry. The main drafter of this standard is Li Junqing.
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