快速、无汞开管测定废水中化学需氧量的研究

Experimental study on method for rapid determination of COD in wastewater efflue nts by mercury-free open-tube.

采用无汞开管法进行了快速测定化学需氧量(ChemicalOxygenDemand,简称COD)的研究,在硫酸-磷酸为介质、重铬酸钾为氧化剂、硫酸银作催化剂、硝酸银和硫酸铬钾为氯离子掩蔽剂的条件下。将样品在玻璃试管中消化,用一台恒温器加热样品,反应温度160～165℃,加热时间只需15min,消解后剩余的重铬酸盐用滴定法或分光光度法测定.试验结果表明,该法的检测限为10.9mg/L。测定范围为40～800mg/LCOD,当COD值大约为85mg/L时,容许氯离子的最高含量为1500mg/L,由于该法不使用剧毒的汞盐,避免了汞对环境的污染,经测定大批量废水样品,结果令人满意。

A mercury-free and open-tube method was given for determining COD ra pi dly, which was reliable, simple and safe. The method employs K 2Cr 2O 7 as ox idant in a medium of H 2SO 4-H 3PO 4, with catalysis by Ag 2SO 4 and with addit ion of AgNO 3 and CrK(SO 4) 2·12H 2O to mask chloride. Samples were digested in glas s tubes and heated at 160-165 ℃ for 15 min in an attemperator. The residual dichromate was t hen determined by titration or spectrophotometry. The results showed that the de tection limit for COD was 10.9 mg/L and in the range of 40～800 mg/L COD values of the detected results were satisfied. When the COD concentration was about 85 mg/L, the maximum acceptable value for the chloride would be 1500 mg/L. The adva n tage of this method avoid using toxic mercuride that could pollute the environme nt. The developed method has been successfully applied to determine COD in large quantities of wastewater effluents samples.