高氯离子低浓度COD水样的分析技术

分析了氯离子的干扰机理和重铬酸钾氧化法测定COD质量浓度的方法原理,进行了氯离子消解时间实验,提出了测定COD质量浓度的方法:先不加硫酸银,只加重铬酸钾和浓硫酸,加热0.5h后取出,冷却5min后加入0.3g硫酸银,继续加热回流1.5h,测定总的表观COD质量浓度值,经氯离子表观COD质量浓度校正后,测定高氯离子水样中低浓度COD质量浓度值。该法能较准确的反映水样的COD质量浓度,且结果重复性好,无污染,成本低,是值得推广的清洁分析方法。

Analysis techniques of low COD in water sample with high chlorine ion

The interference mechanisms of chlorine ion and the method and principle of measurement of COD using the potassium dichromate oxidation method were analyzed. Based on the digestion time experiment on chlorine ion, a method was proposed to measure COD. First, potassium dichromate and oil of vitriol were heated for 0.5h without silver sulphate added. Then, 0.3g silver sulphate was added into the mixture after a 0.5h-cooling. The total apparent COD was measured when the heating and recycling process was continued for 1.5h. The low COD in water samples with high chlorine was rectified by the apparent COD curve of chlorine ion. This method, with the advantages of high duplicate, no pollution, low cost, can well reflect the COD in waters and is a cleaning analysis method worthy of use in practice.