酸性大红的Fe-Cu内电解法还原脱色及其机理

Fe-Cu内电解法使酸性大红还原脱色,其机理是化学还原(零价铁还原和氢加成还原)与电化学还原共同作用的结果,偶氮双键还原为氢化偶氮.在酸性条件下化学还原起主要作用,而在碱性条件下电化学还原起主要作用.循环伏安法显示了铜阴极对酸性大红电催化作用,中性及碱性时比在酸性时更易在铜阴极上还原;而铁炭法中在炭上只有在酸性条件下才有电化学还原作用.酸性大红的FeCu内电解法处理有较宽的pH值适应范围,脱色率可达95%以上,CODCr(化学需氧量)减少50%左右.提高反应温度可以改善酸性大红废水的内电解处理效果.

Reductive Decolorization Mechanism of Acid Red 73 by Fe-Cu Internal Electrolysis

The decolorization of acid red 73 by Fe-Cu internal electrolysis is a result of chemical reduction, including reduction caused by zero valent iron and caused by hydrogen produced in reactions, and electrochemical reduction. The azo double bond is reduced to hydrogenated azo structure. In acidic solution chemical reduction is dominant and in alkaline solution electrochemical reduction is important. Cyclic voltammetry revealed that the cathodic copper had a stronger electrocatalytic activity for the reduction of acid red 73 in neutral and alkaline solution than in acidic solution. At electrodic carbon, the electrochemical reduction of the dye took place only in acidic solution. The Fe-Cu internal electrolysis of acid red 73 accommodates a wider pH range. The decolorization rate is over 95% and COD_ Cr reduces by 50%.The increase of temperature improves the efficiency of treatment.