风冷型恒温回流消解及微量滴定法测定COD  

Measurement of COD with Air-cooling Type Constant Temperature Reflux Digestion and Micro-titration Method

作　　者：吴俊[1] 吴平[2] 

机构地区：[1]苏州科技学院电子与信息工程学院,江苏苏州215009 [2]苏州科技学院环境科学与工程学院,江苏苏州215009

出　　处：《中国给水排水》2016年第8期127-130,共4页China Water & Wastewater

摘　　要：采用国标分析方法测定水样COD时,取用水样量较多,造成银试剂的耗量高和汞的污染。为了达到节银减汞的目的,采用专用的微小水样量恒温回流加热器,将水样取用量由20 m L减为2 m L,达到了减少实际用量、节约银量成本及减少汞污染的明显效果。分析水样量的减少,也相应降低了COD监测的准确度。通过研究专用配套的玻璃微量滴定管(量程范围为3.50 m L),滴定的毛细滴嘴可以确保细滴精度达到0.01 m L。此外,还对滴定平台进行了技术改进,增加了平面LED绿光(510 nm波长)背衬光,加强了指示剂颜色突变的光吸收敏感度,解决了滴定终点精准定位的难点问题,降低了测定过程的偶然误差。The amount of water sample for COD analysis by the international standard method is relatively more than that by the other methods, which usually causes high silver reagent consumption and mercury pollution. In order to achieve the goal of saving silver reagent consumption and reducing mercury pollution, the specific micro-water sample constant temperature reflux heater was adopted, and obvious effects of reducing actual water amount, saving silver reagent consumption and decreasing mercury pollution were achieved by reducing the amount of water sample from 20 mL to 2 mL. The decrease in amount of water sample for analysis also correspondingly reduced the measurement accuracy of COD. By studying the specific supporting glass micro-burette （ range ability 3.50 mL）, the accuracy of titrimetric capillary drip nozzle could reach to 0.01 mL. In addition, the titration platform was reconstructed by enhancing the backing light of flat LED green ray （510 nm wavelength） and increasing the light absorption sensitivi- ty of indicator color immediate change, which solved the difficult problem of titration end point precise positioning and reduced the accidental errors of the measurement process.

关 键 词：COD测定 节银减汞 回流加热 恒温微沸腾 微量滴定 

分 类 号：X832[环境科学与工程—环境工程]