化学需氧量快速应急监测方法研究

A Study of Rapid Emergent Measuring Method for COD

目的:建立一种快速废水化学需氧量(COD)测定方法。方法:对国家标准方法-重铬酸盐法(GB11914-89)的反应条件进行改良研究,选择合适条件,建立快速法;再验证快速法的敏感性和特异性,并与原标准法进行比对。结果:催化剂溶液硫酸银-硫酸溶液优于硫酸银-硫酸、磷酸混合溶液,反应溶液酸度以10.0mol/L为佳;回流时间25～35min,COD达峰值且趋于平稳,C1-的正干扰,用HgSO4作掩蔽剂比AgNO3好。以最佳条件建立的快速法,相对偏差为0.73%～1.69%,相对误差为0.75%～1.69%。与原标准法对照,误差在±2.0%以内。结论:对COD的国家标准方法进行改良,建立了快速COD测定方法,使回流时间由原来的2h缩短为30min,测定结果与原标准方法基本一致。

Purpose:To establish a method for rapidly measuring COD in wastewater.Methods:A modification study was conducted on the basis of the reaction conditions specified in the national standards-the Dichromate Method(GB11914-89)to identify suitable conditions and establish a rapid method;then,the sensitivity and specificity of the rapid method were verified and compared with the original standard method.Results:Catalyst solution silver sulfate-sulfuric acid solution proved to be superior to silver sulfate-sulfuric acid and phosphoric acid mixed solution,and the acidity of the reaction solution was preferably 10.0 mol/L;the flow time was 25～35 min;COD reached its peak value and held steady;with the positive interference of C1,HgSO 4 was a better masking agent than AgNO 3.The rapid method established using the optimum condition had a relative deviation of 0.73%～1.69% and a relative error of 0.75%～1.69%.The error compared with the original standard method was within ±2.0%.Conclusion:The COD measuring method established by modifying the original method in the national standards shortened the backflow time from 2 h to 30 min,and the measuring results were largely consistent with the original standard method.