To remove main disturbing ion, chlorine ion in the COD potassium dichromate reflux method, silver sulfate replaces mercury sulfate as a screening agent.
对cod重铬酸钾回流法中的主要干扰离子，氯化物的消除，选择了用硫酸银代替硫酸汞做掩蔽剂。
2
Iron line replacement method is used to recovery metal silver from silver sulfate in COD waste liquid, and it is reused to analyze, so analysis cost and environment pollution are decreased.