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HJ/T 28-1999 English version translation pdf

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发表于 2019-7-3 13:24:53 | 显示全部楼层 |阅读模式
4.23 Potassium cyanide standard solution: c = 10.0ug (HCN) / ml.
Accurately absorb a certain volume of potassium cyanide standard stock solution (4.22) into a 100mL volumetric flask, dilute it to the mark with 0.1mol/L sodium hydroxide solution (4.18), store in the refrigerator (2 ~ 5), can be stable for 5 days.
4.24 Standard potassium cyanide solution: c(HCN)=1.00 ug/ml
Pipette 10.0 ug/ml potassium cyanide standard solution (4.23) 10.0 ml in a 100 ml volumetric flask and dilute it to the mark with 0.1 mol/L sodium hydroxide solution (4.18).
4.25 phosphate buffer solution: pH=7.00
Weigh 34.0 g of anhydrous potassium dihydrogen phosphate (4.7) and 35.5 g of anhydrous disodium hydrogen phosphate (4.8), dissolve it in water, and transfer it to a 1000 ml volumetric flask. Dilute it to the mark with water.
4.26 Potassium chromate indicator
Weigh 10.0 g of potassium chromate (4.9), dissolve it in a small amount of water, add a silver nitrate standard solution (4.21)drop by drop until a small amount of brick red precipitate is produced, leave it overnight, filter it, and dilute the filtrate to 100 mL with water, and set aside.
4.27 phenolphthalein indicator: c = 0.1%
Weigh 0.1 g of phenolphthalein, dissolve it in 95% ethanol, and dilute it to 100 mL. If it is turbid, then it should be filtered.
4.28 chloramine T solution
Weigh 0.50 g of chlorinated ammonia T (CH3C6H4SO2NClNa·H2O, Chloramine-T) (4.10), dissolve it in a brown thin-mouth bottle, and store it in a refrigerator for 3 days.
4.29 p-dimethylaminobenzalrhodanine indicator
Weigh 0.02 g of p-dimethylaminobenzalrhodanine(paradimethylaminobenzalrhodanine) (4.11) and dissolve it with 100 mL acetone. Store it in a brown thin-mouth bottle and stabilize it for 1 month in the dark.
4.30 isonicotinic acid solution
Weigh 3.0 g of isonicotinic acid (C6H5NO2, Iso-Nicotinic acid) (4.12), dissolve it in 2% sodium hydroxide solution (4.15).After dissolved, dilute it to 200 mL with water.
4.31 pyrazolone solution
Weigh 0.50 g of pyrazolone (3-methyl-1-phenyl-5-pyrazolone, C10H10ON2, 3-methyl-1-pheny-5-pyrazolone) (4.13), dissolve it in 40.0 mL of N,N'-Dimethylamide [HCON(CH3)2, N,N'--dimethylformamide] (4.14).
4.32 isonicotinic acid-pyrazolone solution
Immediately before use, mix the isonicotinic acid solution (4.30) and the pyrazolone solution (4.31) in 5:1 volume ratio, and store it in a brown reagent bottle.
5. Instrument
5.1 spectrophotometer: with 1cm cuvette
5.2 colorimetric tube with stopper: 25mL
5.3 brown acid burette: 25mL
5.4 sampling instrument
5.4.1 Organized emission monitoring sampling instrument
Refer to 9.3 Configuration of sampling instrument in GB16157-1996
5.4.1.1 Sampling tube
Made of stainless steel, hard glass or Teflon, the diameter of the tube is 6~8mm and has a thermal jacket that can be heated to above 120 .
5.4.1.2 Sample absorption device
Porous glass absorption bottle, 125mL
5.4.1.3 Flow metering device
Refer to 9.3.6 of GB16157-1996
5.4.1.4 Vacuum pump
Refer to 9.3.7 of GB16157-1996
5.4.1.5 Connecting tube
Silicone rubber tube or lined latex tube with PTFE film
5.4.2 Unorganized emission monitoring sampling instrument
5.4.2.1 intake pipe
Polyethylene, Teflon hose, head connected to a glass funnel
5.4.2.2 Sample absorption device
Multi-hole glass plate absorption tube: 10~25mL
5.4.2.3 Flow metering device
Refer to 9.3.6 of GB16157-1996
5.4.2.4 Air pump
Refer to 9.3.7 of GB16157-1996
5.4.2.5 connecting pipe
Same as 5.4.1.5
6 Sample collection and preservation
6.1 Organized emission sample collection
6.1.1 Sampling position and sampling point
The sampling position and sampling point are determined according to 9.1.1 and 9.1.2 of GB16157-1996.
6.1.2 Connection of sampling device
Refer to Figure 28 in part 9.3 of GB16157-1996, connect the sampling system in the order of sampling tube, sample absorption device, flow metering device and air pump. The connecting pipe should be as short as possible. Check the air-tightness and reliability of the sampling system according to the requirements of 9.4 in GB16157-1996.
6.1.3 Sample Collection
Connect two 125ml porous glass plate absorption bottles containing 20mL sodium hydroxide absorption liquid B (4.18) respectively, then connect it to the sampling system, and the sampling tube head is stuffed with an appropriate amount of alkali-free glass wool to penetrate the sampling point of the exhaust pipe. Sample at a flow rate of 0.5L/min for 10~30min, record the flow rate, time, temperature, pressure, etc., seal the inlet and outlet of the absorption bottle, and transport it back to the laboratory avoiding light.
6.2 Unorganized emission sample collection
6.2.1 Sampling position and sampling point
Determine the location of the unorganized emission monitoring point according to Appendix C of GB16297-1996, or determine the sampling point according to other specific requirements.
6.2.2 Connection of the sampling device
Connect the sampling device in the order of the air inlet pipe, sample absorption device, flow metering device and air pump. The connecting pipe should be as short as possible. If it is not necessary, the air pipe should not be connected before the sample absorption device. Check the airtightness and reliability of the sampling system with reference to the requirements of 9.4 of GB16157-1996.
6.2.3 Use a porous glass plate absorption tube containing 0.05 mol/L sodium hydroxide absorption solution A (4.17) 5 mL, and sample at a flow rate of 0.5 L/min for 30 to 60 minutes. Record the sampling flow rate, time, temperature, pressure, etc., seal the inlet and outlet of the absorption tube, and transport it back to the laboratory avoiding light.
6.3 Sample preservation
If the sample cannot be measured on the same day of the collection, the sample should be sealed and stored at 2~5 for a period of not more than 48 hours. Sunlight should be avoided during sampling, transportation and storage.
6.4 sampling protection
The person who samples the organized exhaust must have more than two people and bring with gas mask to enter the site for sampling.
7 analysis steps
7.1 Drawing a calibration curve
Take 8 25ml colorimetric tubes with stopper and configure the standard color column according to Table 1.
Table 1 potassium cyanide standard color column
Tube No.
0
1
2
3
4
5
6
7
Potassium cyanide standard solution, ml
0.00
0.20
0.50
1.00
2.00
3.00
4.00
5.00
Sodium hydroxide absorption liquid, ml
5.00
4.80
4.50
4.00
3.00
2.00
1.00
0.00
Hydrogen cyanide content, μg
0.00
0.20
0.50
1.00
2.00
3.00
4.00
5.00
Add 1 drop of 0.1% phenolphthalein indicator (4.27) to each tube respectively, add 0.6% acetic acid solution (4.19) drop by drop with shaking, until the phenolphthalein indicator just fades, then add 5.00 ml phosphate buffer solution (4.25), shake well, and add 0.20ml of chloramine-T solution (4.28), immediately cover the stopper, gently shake well, then place for 5min, add isonicotinic acid-pyrazolone solution (4.32) 5.00ml, immediately cover the stopper and shake well, then dilute it to the mark with water and shake well. Place it at 20~35 for 40min. Measure the absorbance at 638 nm by using 1 cm cuvette, with water as a reference. From the absorbance and its corresponding hydrogen cyanide content (μg), draw its calibration curve and calculate its linear regression equation.
7.2 Sample determination
7.2.1 Determination of unorganized emission samples
After sampling, transfer the sample into a 25 ml colorimetric tube with stopper, and wash the absorption tube twice with a small amount of water. The washing liquid is also transferred into the colorimetric tube with stopper. And the total volume should not exceed 10 ml, then add 1 drop of 0.1% phenolphthalein indicator (4.27). The following steps are as same as drawing the calibration curve.
7.2.2 Determination of organized emissions samples
After sampling, transfer the absorption liquid of the first absorption bottle and the second absorption bottle into a 50 ml volumetric flask, and wash the first and the second absorption bottle with a small amount of water separately. And transfer the washing liquid into a 50 ml volumetric flask. Finally dilute it to the mark and shake well. Absorb 5.00 ml of sample solution in a 25 ml colorimetric tube with stopper. The following steps areas same as drawing the calibration curve.
8 calculation and result
8.1 Calculation the sample concentration of unorganized emission
Hydrogen cyanide (HCN, mg/m3)=W/Vnd
In the formula: W--hydrogen cyanide content in the sample solution, μg
Vnd--converted to the dry gas volume under standard conditions, L
8.2 Calculation sample concentration of organized emission
Hydrogen cyanide(HCN, mg/m3)=(W/Vnd)x(Vt/Va)
In the formula: W--the content of hydrogen cyanide in the sample solution taken during the measurement, μg
Vnd--converted to the dry gas volume under standard conditions, L
Vt--the total volume of the sample solution, ml
Va--the volume of the sample solution taken during the measurement, ml
Calculate Vnd according to 10.1 or 10.2 of GB 16157-1996
8.3 Calculation of “emission concentration” of organized hydrogen cyanide emissions
Calculate the “emission concentration” of hydrogen cyanide according to 11.1.2 or 11.1.4 of GB16157-1996.
8.4 Calculation of the “emission rate” of organized hydrogen cyanide emissions
Calculate the hydrogen cyanide emission rate according to 11.4 of Gb16157-1996
8.5 Calculation of “unorganized emission monitoring concentration value” of hydrogen cyanide
8.5.1 Calculate the average concentration of hydrogen cyanide of an unorganized emission monitoring point as follows:
file:///C:/Users/Abel/AppData/Local/Temp/msohtmlclip1/01/clip_image002.jpg
In the formula: c--the average concentration of hydrogen cyanide of an unorganized emission monitoring point;
ci--the concentration of hydrogen cyanide in a sample
n--Number of samples collected at an unorganized emission monitoring point
8.5.2 Calculation of “unorganized emission monitoring concentration value”
Calculate the “unorganized emission monitoring concentration value” of hydrogen cyanide according to C2.3 in Appendix C of GB16297-1996
9 precision and accuracy
9.1 Accuracy
Five laboratories measure a uniform sample with HCN concentration of 0.37 mg/m3. The standard deviation of the method is 0.01 mg/m3, the repeatability relative standard deviation is 3.1%, and the repeatability is 0.030 mg/m3. The method of reproducibility standard deviation is 0.016 mg/m3, the reproducibility relative standard deviation is 4.1%, and the reproducibility is 0.040 mg/m3.
The relative standard deviation of the actual samples determined by these 5 laboratories is between 0.81% and 11%.
9.2 Accuracy
Five laboratories measure a uniform sample of 0.37 mg/m3 respectively, and the relative error of determined average values is 2.9%. The relative error of each laboratory is between ±5.4%.
The recoveries of the uniform sample among those five laboratories are between 93.2% and 103%, and the recoveries of the actual samples are between 90.1% and 102%.
10 instructions
10.1 Hydrogen cyanide is a volatile toxic substance. During the operation, the colorimetric tube should be tightly sealed except for the addition of reagents.
10.2 The difference between the temperature at which the calibration curve is drawn and the temperature at which the sample is measured should not > 3 .
10.3 If a silver nitrate reference reagent can be obtained, the silver nitrate standard solution can be prepared directly, eliminating the calibration step.
10.4 In order to reduce the blank value of the reagent, it is preferred to use colorless N,N' dimethylformamide in the experiment.
10.5 Waste liquid containing potassium cyanide should be treated with trivalent iron salt or bleaching powder, then discharged.
10.6 The presence of oxidant (such as Cl2) and hydrogen sulfide may interfere with the determination. The method for detecting the presence of oxidant and hydrogen sulfide in the sample and eliminating interference is described in Appendix A of this standard.
Appendix A
Method for testing oxidants and sulfides in samples and eliminating interference
A1 Check the sample for the presence of oxidant (such as available chlorine). Take 1 drop of the sample onto the starch-potassium iodide test paper. If it turns blue, then the oxidant is present in the sample. The determination of hydrogen cyanide cannot be carried out if a significant amount of oxidant is present. If there is a small amount of oxidant, a certain amount of sodium sulfite solution could be added to the sample solution to eliminate the interference. The specific practice: take two identical copies of the same volume of the same sample, and add one to three pieces of starch-potassium iodide test paper to one of the samples, acidified with sulfuric acid, and titrated with sodium sulfite solution until the starch-potassium iodide test paper changes from blue to colorless, record the used amount of sodium sulfite. For another sample, without adding test paper and sulfuric acid, only add the same amount of sodium sulfite solution as mentioned before. And the solution is titrated with hydrogen cyanide.
A2 Check if there is sulfide in the sample. Take 1 drop of the sample on the lead acetate test paper. If it turns black, it indicates the presence of sulfide. If the sample contains a small amount of sulfide, it can be removed by pre-distillation. Add 2ml of 0.02mol/L silver nitrate solution before distillation.
Additional information:
This standard is proposed by the Science and Technology Standards Department of the State Environmental Protection Administration.
This standard was drafted by China Textile University.
The main drafters of this standard: Yan Danli, Wang Yonghui, Jiang Peihua.
This standard is entrusted to China Environmental Monitoring Station to Explain.

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