光同时诱导水中Cr(Ⅵ)的还原与橙黄Ⅱ的氧化

Photo-induced Simultaneous Reduction of Cr(Ⅵ) and Oxidation of OrangeⅡ in Water

利用照明金属卤化物灯为光源,研究了含Cr(Ⅵ)和染料橙黄Ⅱ模拟混合废水中Cr(Ⅵ)的还原和橙黄Ⅱ的氧化脱色;讨论了pH值、Cr(Ⅵ)、橙黄Ⅱ初始浓度对光反应的影响;对反应机理进行了初步探讨。实验表明,卤灯照射Cr(Ⅵ)和橙黄Ⅱ混合溶液能同时实现Cr(Ⅵ)的光还原和橙黄Ⅱ的脱色,同时提高Cr(Ⅵ)和橙黄Ⅱ的浓度更利于Cr(Ⅵ)和橙黄Ⅱ的处理;酸度越大,Cr(Ⅵ)的光还原率和橙黄Ⅱ的脱色率越大;Cr(Ⅵ)浓度越大,Cr(Ⅵ)还原率越小;反应初始速率越大,橙黄Ⅱ的脱色率越大;橙黄Ⅱ浓度越大,Cr(Ⅵ)的光还原率、橙黄Ⅱ的脱色率及反应初始速率越大。橙黄Ⅱ是影响反应速率的主要浓度因素,发生反应的首先是橙黄Ⅱ吸收光能成为活化状态,然后Cr(Ⅵ)与激发态橙黄Ⅱ发生氧化还原反应。利用可见/紫外光诱导水中高价重金属(如Cr(Ⅵ))的还原和有机污染物(如偶氮染料)的氧化,能实现对重金属和有机污染物的同时处理。

Simultaneous treatment of Cr （Ⅵ） antl Orange Ⅱ in wastewater was lnvestigated with a metal halide lamp as light source. The affecting factors on the photoreaction were discussed, including pH and the initial concentrations of Cr（Ⅵ） and Orange Ⅱ. The reaction mechanism was preliminarily studied. Under the irradiation of the metal halide lamp, the photoreduction of Cr（Ⅵ） and photooxidation of Orange Ⅱ occurred simultaneously in wastewater mixtures. It is beneficial to the treatment of Cr（Ⅵ） and Orange Ⅱ to increase the concentrations of Cr（Ⅵ） and Orange Ⅱ. The photoreduction rate of Cr（Ⅵ） and the discoloration rate of Orange Ⅱ increase with increasing acidity. The higher the concentration of Cr（Ⅵ） , the lower the photoreduction rate of Cr（Ⅵ）. The higher the initial rate, the higher the discoloration rate ofOrange Ⅱ ;the higher the concentration of Orange Ⅱ , the higher the photoreduction rate of Cr（Ⅵ） , the discoloration rate of Orange Ⅱ and the initial rate. Orange Ⅱ is the dominant species influencing the reaction rate. The reaction mechanism may be that Orange Ⅱ is activated by absorbing energy first, and then reacts with Cr（Ⅵ） via redox. Simultaneous treatment of Cr（Ⅵ） and organic compounds in water can be induced by UV-Vis light. These findings suggest that the method may be a new approach to remove high valent heavy metals and organic compounds simultaneously.