氯气校正法测定高氯水COD方法的标准化研究

doi:10.19965/j.cnki.iwt.2022-0580

摘要/Abstract

摘要：

针对现行测定高氯水中COD的标准方法（氯气校正法）存在的检出限高、适用范围窄等问题，研究了氧化剂浓度、消解回流吸收装置、取样体积、碱液端氯气吸收导管、加热温度等实验条件，优化后方法的检出限由原方法的30 mg/L降至4 mg/L，与地表水环境质量标准相衔接，拓宽了方法适用范围，解决了当前高氯离子、低COD地表水无相应监测方法的技术盲区，满足当前水环境管理需要。优化方法的试剂使用量较原方法减半，减少了试剂对环境的二次污染。研究发现，对同一水样进行多次平行测定，氯气校正值和表观COD并不一定相同或相近，但表观COD扣除氯气校正值后，真实COD具有很好的精密度和正确度，从微观角度解释了产生该现象的机理。指出测试中需重点关注的加热温度、消解回流吸收装置气密性和材质等关键问题，方法准确可靠，精密度和准确度满足要求，具有普适性，易推广使用。对高氯地表水和废水水样的测定相对标准偏差范围为3.6%~6.5%，加标回收率在92.4%~94.3%，结果令人满意。

关键词: COD, 高氯水, 氯气校正法, 环境管理

Abstract:

Aiming at the problems of high detection limit and narrow application range of the current standard method （chlorine calibration method） for the determination of COD in high chlorine water， the experimental conditions such as oxidant concentration， abatement reflux absorption device， sampling volume， chlorine absorption tube at the alkali end and heating temperature were studied. The optimized method reduced the detection limit from 30 mg/L to 4 mg/L， which was in line with the environmental quality standard of surface water. The scope of application of the method was broadened， and the blind area of no corresponding monitoring method for high chloride ion and low COD surface water had been solved to meet the current needs of water environment management. Compared with the original method， the amount of reagent used in the optimized method was reduced by half， reducing the secondary pollution of the environment. It was found that the chlorine calibration value and apparent COD were not necessarily the same or similar for multiple parallel measurements of the same water sample， but the apparent COD had good precision and accuracy after deducting the chlorine correction value， which explained the mechanism of the phenomenon from a microscopic perspective. It was pointed out that the test needs to focus on the key issues such as heating temperature， air tightness and material of the digestion reflux absorption device. The method was accurate and reliable， the precision and correctness met the requirements， it was universal and easy to promote the use. The relative standard deviations for the determination of high chlorine surface water and water sample were in the range of 3.6%-6.5%， and the recovery rate were in the range of 92.4%-94.3%， which were satisfactory.

Key words: COD, high chlorine water, chlorine emendation method, environmental management

中图分类号:

X832

王文雷, 宋永超, 刘金芝, 马振国, 王振华. 氯气校正法测定高氯水COD方法的标准化研究[J]. 工业水处理, 2023, 43(4): 162-169.

Wenlei WANG, Yongchao SONG, Jinzhi LIU, Zhenguo MA, Zhenhua WANG. Study on standardization of determination of COD in high chlorine water by chlorine emendation method[J]. Industrial Water Treatment, 2023, 43(4): 162-169.

https://www.iwt.cn/CN/Y2023/V43/I4/162

图/表 14

参考文献 7

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氯离子质量浓度/ （mg·L^-1）	30%HgSO₄溶液加入量/mL	Ag₂SO₄-H₂SO₄加入量/mL	回流后加水量/mL
1 000	0.3	15	40
2 000	0.5	16	41
3 000	0.8	16	42
4 000	1.0	16	43
6 000	1.5	17	44
8 000	2.0	17	46
10 000	2.5	18	47
12 000	3.0	18	48
15 000	3.8	19	50
18 000	4.5	19	52
20 000	5.0	20	54

氯离子质量浓度/ （mg·L^-1）	30%HgSO₄溶液加入量/mL	Ag₂SO₄-H₂SO₄加入量/mL	回流后加水量/mL
1 000	0.3	15	40
2 000	0.5	16	41
3 000	0.8	16	42
4 000	1.0	16	43
6 000	1.5	17	44
8 000	2.0	17	46
10 000	2.5	18	47
12 000	3.0	18	48
15 000	3.8	19	50
18 000	4.5	19	52
20 000	5.0	20	54

氧化剂/（mol·L^-1）	氯离子质量浓度/（mg·L^-1）	理论COD/（mg·L^-1）	COD测定值/（mg·L^-1）	RE/%
0.025 0	75	17.0	16.5	2.9
	100	22.6	22.3	1.3
	150	33.9	33.2	2.1
	200	45.2	44.8	0.9

氧化剂/（mol·L^-1）	氯离子质量浓度/（mg·L^-1）	理论COD/（mg·L^-1）	COD测定值/（mg·L^-1）	RE/%
0.025 0	75	17.0	16.5	2.9
	100	22.6	22.3	1.3
	150	33.9	33.2	2.1
	200	45.2	44.8	0.9

氧化剂/（mol·L^-1）	氯离子质量浓度/（mg·L^-1）	表观COD/（mg·L^-1）	氯气校正值/（mg·L^-1）	COD测定值/（mg·L^-1）	RE/%
0.025 0	1 000	35.7	5.6	30.1	2.4
	2 000	36.2	8.0	28.2	-4.1
	5 000	34.5	4.8	29.7	1.0
	10 000	40.6	9.4	31.2	6.1
	20 000	40.8	11.0	29.8	1.4

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