纳米ZnO膜光催化氧化测定化学需氧量的应用研究

提出了一种利用石英管负载的纳米ZnO膜光催化测定化学需氧量的方法.通过添加无机强氧化剂K₂Cr₂O₇提高光催化体系对有机物的降解效率，在光催化氧化有机物的同时,K₂Cr₂O₇也会被纳米ZnO表面的光生电子还原为Cr(Ⅲ)，根据Cr(Ⅲ)浓度的变化量确定水样化学需氧量的值.实验结果表明，在50~1 000 mg/L的COD范围内，Cr(Ⅲ)浓度的变化量与标准水样中的COD_Cr值成正比例关系，检出限为20 mg/L.将该方法用于实际水样检测，分析时间短，减少了二次污染，光催化反应后水样无需后处理可直接进行测定,且与国家COD标准分析法具有好的相关性.

Determination of Chemical Oxygen Demand Values by Photocatalytic Oxidation Using Nano ZnO Film on Quartz(Chinese)

A COD measurement by photocatalytic oxidation using nano ZnO film was investigated.K₂Cr₂O₇ was added into the solution to enhance the efficiency of photocatalytic degradation,and simultaneously K₂Cr₂O₇ was reduced to Cr(Ⅲ) by photogenerated electrons which were adsorbed on the surface of ZnO.The measuring principle was based on direct determination of Cr(Ⅲ) concentration which was proportional to the COD value.Under the optimized experiment condition,the application range was 50~1 000 mg/L,and the detection limit was 20 mg/L.The immobilization of photocatalyst on the supports could not only solve the problem of low recovery of the catalyst and hard separation from the solution,but also overcome its shortcoming of poor stability.Applying this method to the determination of real samples,it was found to be rapid and environmentally friendly.Additionally,the method proposed above for determination of COD was in excellent correspondence with values obtained by using the conventional method.