水和废水中化学需氧量测定方法的改进研究

摘要

This paper introduced an improved method for determining CODcr in water.Compared with GB method, setting 30 ml recycle flow as measure standard will reduce cost of concentrated sulfuric acid and silver sulfate by 50%, reduce the time from 120 min to 30 min, reduce electricity and water consumption over 75%.At the same time, satisfied the requirement of CODcr de-termination in all kinds surface water and waste water.Research of masking agent for chlorine in water samples indicate:using Hg-SO4 as masking agent, when 10 times weight of Cl -,the recovery rate(CODcr =100 mg/L)is about 110%~120%, when 30~40 times weight of Cl -, the recovery rate is about 100%.This paper also discussed condition and mechanism of HgSO4 masking effect for Cl-.when adding H2 SO4-before HgSO4 ,the cost of HgSO4 can reduce more than 70%.%在水的CODcr测定中,将30 ml回流量确定为常规检测回流量,可节省浓硫酸和硫酸银用量50%;将消解回流时间从120 min缩短为30 min,已满足对地表水和各类废水中CODcr的准确测定,可节省水电费用75%以上,含氯水样中Cl-的掩蔽研究表明:按国标法用10倍Cl-重量的HgSO4 掩蔽Cl-,加标(CODcr =100 mg/L)回收率为110%~120%左右,用30~40倍Cl -重量的HgSO4 掩蔽Cl-,加标回收率为100%左右,对HgSO4 掩蔽Cl-的条件和机理作了适当探讨.另外,采用加入H2 SO4-后加入HgSO4 的方法可减少HgSO4 的耗用量70%以上.