钛基氧化物阳极氧化降解水中2,4-二氯酚

Degradation of 2,4-dichlorophenol by anodic oxidation using Ti-based oxide electrodes

采用热氧化法制备了具有TiO2、RuO2和IrO2涂层的钛基氧化物电极(Ti/TiO2/RuO2/IrO2),并以其为工作电极考察了:①水中2,4-二氯酚(DCP)的循环伏安特性;②pH值、阳极电位和反应时间对阳极氧化降解DCP的影响;③阳极氧化对DCP水溶液可生化性的影响.结果表明,电极的氧化物负载量显著影响DCP的循环伏安特性.较高的介质pH值利于DCP的电化学氧化降解,而低pH值更易导致DCP挥发.低阳极电位下,DCP主要通过阳极直接氧化降解,因受电流密度过低的限制其降解效果较差;高阳极电位下,DCP主要通过阳极间接氧化降解,当阳极电位为1.8V,反应时间为360min时,DCP去除率可达100%,COD的去除超过50%,但能耗较高.COD的检测与紫外-可视光谱曲线表明,DCP的电化学氧化降解过程产生了有机中间体.Ti/TiO2/RuO2/IrO2阳极氧化可显著提高DCP水溶液的可生化性,表明其在氯酚废水预处理或脱毒领域有一定应用潜力.

Ti-based oxide electrodes coated with IrO2,RuO2 and TiO2 （Ti/IrO2/RuO2/TiO2） prepared by a thermal oxidation process were employed to investigate：① the cyclic voltammetry characteristics of 2,4 dichlorophenol （DCP） in water solution; ② the influences of pH,anodic potential and reaction time on DCP degradation by the anodic oxidation process; ③ the influence of anodic oxidation on the bio-degradability of DCP solution. The results showed that the loading of oxides had a significant effect on the cyclic voltammetry curves. A higher pH was beneficial to the electrochemical oxidation of DCP while a lower pH tended to cause more DCP to volatize. At lower anodic potentials,DCP degradation was ascribed to the direct electrochemical oxidation and in this case,degradation was poor because of the lower current density. At higher anodic potential,DCP degradation was ascribed to indirect electrochemical oxidation. A DCP removal of 100% and a COD removal of higher than 50% were achieved at an anodic potential of 1.8 V with a reaction time of 360 min,but the power consumption was high. The results of COD reduction and the UV-visible spectra indicated that some organic intermediates were produced during the course of DCP degradation. Anodic oxidation using the Ti/ IrO2/RuO2/TiO2 electrode was able to enhance the bio-degradability of DCP solution,which suggests it is a promising alternative for the pretreatment or detoxification of wastewaters containing chlorophenols.