不同结构网基Ti/Sb-SnO2电极电催化降解苯酚效能

Electrochemical catalytic oxidation efficiency of phenol on mesh Ti/Sb-SnO with various structures

以不同孔结构及面积的网基Ti/Sb-SnO2电极为研究对象,考察其电催化氧化苯酚的效能。研究发现:各网基电极能够有效的去除废水中的污染物,在电流密度为10mA/cm2,反应20min后,面积为69.6cm2电极(M3)的TOC去除率为29.02%,是面积为57.8cm2(M2)、49.6cm2(M1)、42cm2(M0)电极的1.09倍、1.20倍、1.57倍;而M3的·OH量为M2、M1、M0的1.22倍、1.78倍及2.64倍,TOC去除速度明显小于·OH的生成速度,这是由于·OH的寿命较短、析氧副反应与·OH生成过程产生竞争,并且当反应为传质控制时,即使·OH产量较高,电极表面不能被完全利用;COMSOL结果表明过密的网结构使电场沿电极表面呈现的变化越小,进而影响电极的传质性能。增加电极面积是提高污染物处理效果的有效方法之一,然而,过高的面积会提高系统的能耗、降低矿化电流效率及传质性能。

Effect of Ti/SnO2-Sb electrodes on mesh substrate with different structure and area on electrocatalytic oxidation of phenol was investigated.The results showed that the mesh electrode can degrade organics in wastewater effectively.Under the current density of 10mA/cm2 and treatment time of 20 min,29.02%TOC was removed on the electrode with area of 69.6cm2(M3),which was 1.09,1.20and 1.57times of electrode area of 57.8cm2(M2),49.6cm2(M1),42cm2(M0).By comparison,·OH amount generated on M3was 1.22,1.78and 2.64times of M2,M1and M0.This lower increment of TOC removal compared to·OH was probably ascribed to the relative short lifetime of·OH and the competition of side reaction of oxygen evolution reaction on electrode surface.In addition,when the degradation reaction was dominated by mass transport process,the electrode surface was not utilized completely for electro-catalytic degradation reaction even at a condition of more·OH production.The COMSOL results indicated that the electric field variation along the electrode surface was smaller due to the dense network structure,which further affected the mass transfer performance of the electrode.Although increasing the electrode area is an effective method to improve the efficiency of organic degradation,however,excess area will increase the energy cost,reduce the mineralization current efficiency and mass transfer performance of the system.