光电催化法在电镀废水COD测定中的应用

The Application of the Photoelectric Catalysis on the Chemical Oxygen Demand(COD) Determination of the Electroplating Wastewater

电镀废水成分复杂,除含有重金属离子外,还含有各种有毒、有害、难降解的有机物.传统的重铬酸钾氧化法在测定复杂电镀废水的化学需氧量（Chemical Oxygen Demand,COD）时,会产生明显的测定误差,同时重铬酸钾法还无法测定低浓度水体的COD.此外,重铬酸钾氧化法还存在着测定时间长（2~4 h）等问题.对于上述问题,开展了光电催化法在电镀废水COD测定中的应用研究.结果表明,光电催化法在多种不同类型有机物的测定中,其耗竭反应库伦净电量（Q_（net））与理论COD值（ρ（COD））之间均呈现良好的线性关系Q_（net）=0.018 71ρ（COD）-0.026 33,相关系数r=0.991 9,其检测限为0.50 mg/L,相对标准偏差小于5%,测定时间小于5 min.光电催化法在测定低浓度的COD时表现出明显的优势,而在测定复杂电镀废水时,其测定结果更为合理.

Electroplating wastewater with complex composition contains various poisonous, harmful and refractory organic matters besides a large quantity of heavy metal ions. The traditional potassium dichromate oxidation method will lead to obvious measurement errors in determination of the chemical oxygen demand （COD） of complex electroplating wastewater and the method is also impossible to determine the COD of the low concentration water body. Also, there exist some other problems such as the 2--4 h cost of time. To avoid those problems, the application of the photoelectric catalysis method on the determination of the electroplating wastewater COD has been researched. The results indicate that the net charges and the theoretical COD of different kinds of organic matters are in good linear relationship, the equation of which is Qnet = 0. 018 71p （COD） - 0. 026 33. Besides, the correlation coefficient is 0. 991 9, the detection limit is 0. 50 mg/L, the relative standard deviation is lower than 5%, and the determination takes less than 5 minutes. The photoelectric catalysis method shows obvious advantage on the determination of low COD concentratioru And the results of the determination of the complex electroplating wastewater are more reasonable.