铬法化学需氧量测定的影响因素分析及改进措施

通过分析铬法化学需氧量测定的操作过程和影响因素,指出水样有机质浓度、悬浮物粒径及含量、氯离子含量、移液管尖嘴口径是影响高浓度有机废水化学需氧量测定的主要因素,可通过控制取样量和稀释倍数、选择合适的重铬酸钾标准溶液浓度和加入量、合适的硫酸亚铁铵标准溶液浓度、充分振摇水样、把握好取样时机、改造取样移液管、加入适宜量的硫酸汞克服氯离子干扰等改进措施减少测定误差。

The Influencing Factors Analyses and Improvement Measures of COD Determination with Potassium Dichromate Method

Through the analysis of the operating process and influencing factors of COD determination with potassium dichromate method, this paper points out that the organic matter concentration, suspended particle size and content, chloride ion content, and pipette nozzle diameter are the major factors which influence COD determination of high concentration organic wastewater. It can be through some improvement measures to reduce measurement error,which include the control sample quantity and dilu- tion ratio,choosing the suitable potassium dichromate standard solution concentration and volume, appropriate concentration of ammonium ferrous sulfate standard solution,fully vibration water sample, the sampling time, transformation sampling pipette, add appropriate amount of mercury sulfate chloride ion to overcome interference.