用硝酸银消除高浓度氯离子对COD测定的干扰及测定废液中银的回收

分析了氯离子的干扰机理，提出了用硝酸银代替硫酸汞消除氯离子干扰测定高氯离子水样COD的分析方法，同时对COD废液的处理及废液中银的回收利用进行了研究。实验结果表明，该法具有较好的准确性和重复性，其相对误差均在国家规定的允许范围内；COD废液中的银经分离后，用Zn—H2SO4体系还原回收，银回收率为94．8％，回收的银粉纯度为99．6％，且可实现COD废液中银的循环使用。

Elimination of High Concentration Cl- Interference in COD Determination by Silver Nitrate and Recovery of Silver from Produced Waste Liquor

The interference mechanism of Cl^- in COD determination was analyzed and the new method of using silver nitrate instead of mercuric sulfate to eliminate the Cl interference was put forward. The treatment of the waste liquor produced in COD determination and the recovery of silver from the waste liquor were studied. The experimental results show that. This method is veracious and repeatable with relative error in the range of national standard; Silver in the waste liquor can be recovered by separation and reduction in Zn-H2SO4 system; The recovery of silver is 94.8% and the purity of recovered silver powder is 99.6%, which indicate that the silver in the waste liquor can realize recycling.