废水中残留过硫酸盐对COD检测的干扰及消除方法

Interference of residual persulfates in wastewater to COD detection and elimination

为研究活化过硫酸盐氧化法处理有机废水时残留的过硫酸盐对水样COD测定产生的误差影响,考察了过硫酸根对COD测定的影响情况,分析干扰机理并提出消除影响的优化方法。研究表明,可将352、420 nm作为测定过硫酸盐阴离子的波长,以忽略来自试剂基质的光谱干扰。过硫酸盐活化处理水样后,溶液中若含有较高浓度过硫酸根离子(0~25 g/L),浓度测定方法为稀释水样后于352 nm处测定吸光值,线性关系方程式为y=0.0214x-0.0013,R^(2)=0.9992;若含有低浓度过硫酸根(0~2.5 g/L),应在未稀释水样的情况下于420 nm处测定吸光度,线性关系方程式为y=0.2556x-0.006,R^(2)=0.9993;过硫酸盐浓度与其消耗COD值之间的线性关系方程为y=18.83894x-7.11549,R^(2)=0.99926。

To study the influence of residual persulfates during the treatment of organic wastewater by activated persulfate oxidation on the determination of COD in water samples,the influence of persulfate ion on the determination of COD is investigated,the interference mechanism is analyzed and the optimized method to eliminate interference is proposed.Research results show that 352 nm and 420 nm wavelengths can serve as the determination of persulfate anions to ignore the spectral interference from the reagent matrix.If the solution contains a high concentration of persulfate ion(0-25 g·L^(-1))after water sample has been treated by persulfate activation,the absorbance value of diluted water sample at 352 nm is determined,the linear relation equation is y=0.0214 x-0.0013,R^(2)=0.9992.If the solution contains a low concentration of persulfate ion(0-2.5 g·L^(-1)),the absorbance shall be determined at 420 nm for undiluted water sample,and the linear relation equation is y=0.2556 x-0.006,R^(2)=0.9993.A linear equation between the concentration of persulfates and COD value consumed is y=18.83894 x-7.11549,R^(2)=0.99926.