低分子有机酸对染料废水电催化氧化的影响

Effect of low molecular organic acids on electrocatalytic oxidation of dye wastewater

研究了二维模式下,形稳性阳极(dimension stable anode,DSA)作为电极材料处理以不同比例混合的酸性大红3R(Acid Red 3R,3R)与草酸(oxalic acid,OA)模拟废水。通过COD、TOC的测定和紫外-可见光谱分析等手段及电化学性能测试可以得出,草酸在电催化降解时所需要的电流密度为10 m A/cm2,明显低于3R电解时所需的电流密度25 m A/cm2。在电催化降解混合模拟染料废水时,电解可以有效破坏发色基团,易降解的有机组分OA优先被氧化,同时会提高难降解有机组分3R的去除效率。此外,废水的p H的不同能导致电催化机理的差异。在p H较低时,阴极的析氢反应占主导地位,使p H升高,而p H较高时,阳极的析氯反应产生Cl2,其水解产生H3O+,同时有机组分被氧化成有机酸,使p H降低。

A dimensionally stable anode（ DSA） was used in 2D mode as the electrode material to handle simulated wastewater comprising Acid Red 3R（ 3R） and oxalic acid（ OA） mixed in different proportions. From the results of COD,TOC,UV-visible spectroscopy,and electrochemical measurements,it can be concluded that the current density required for OA in electrocatalytic degradation was 10 m A / cm^2,which was significantly lower than 25 m A / cm^2 required for 3R. In the electrocatalytic degradation of mixed dye wastewater,electrolysis can effectively decompose the chromophore or dye,and the degradable organic component OA would be oxidized preferentially,which would improve the removal efficiency of the refractory organic component,3R. In addition,the wastewater pH causes differences in the electrocatalytic mechanism. At low pH,the cathodic hydrogen evolution reaction dominates that increases pH. When the pH is high,Cl2 is produced by the chlorine reaction at the anode,which forms H3O^＋by hydrolysis,while the organic component is oxidized to organic acid due to the decrease in pH.