硫酸镍做催化剂测定COD

The determination of COD by using nickel sulfate as catalyst

对化学需氧量(COD)的测定,在国标方法中是以硫酸银做催化剂。试验研究表明,以硫酸镍替代硫酸银做催化剂,测定理论值分别为500、250mg/L的COD标准溶液(邻苯二甲酸氢钾溶液),相对标准偏差为0.9%～2.7%;测定含氯离子1000mg/L、COD理论值分别为500、250mg/L的COD标准溶液(含氯离子1000mg/L的邻苯二甲酸氢钾溶液),相对标准偏差为1.9%～3.7%;测定某工业废水,与用硫酸银做催化剂相比较,相对误差为-1.5%;对理论值为250mg/L的COD标准溶液做加标实验,加标量分别为100、200mg/L,加标回收率为99%～101%。试验结果的重复性、准确度和加标回收率均符合实验室质量控制指标的要求。

Silver sulfate is used in National Standard as catalyst to determine chemical oxygen demand（COD）. The experimental research shows that when nickel sulfate is used as catalyst instead,to determine COD standard solution （potassium biphthalate solution） with theoretical values 500,250 mg/L respectively, its relative standard deviations are 0.9%- 2.7% ;but to determine COD standard solution containing chloride ions 1 000 mg/L of potassium biphthalate solution with theoretical values 500,250 mg/L respectively,its relative standard derivations are 1.9%- 3.7%. When a certain kind of industrial wastewater is determined,compared with using silver sulfate as catalyst,the relative error is -1.5%. When the theoretical value of COD standard solution is 250 mg/L,the scalar quantities are 100,200 mgc/L,the recovery rates are 99%-101%. The repeatability and accuracy of the results and the recovery rate of scalar quantities accord with the quality control indexes in laboratory.