光电化学协同催化降解孔雀绿的研究

Studies on Photo-electron-chemical Catalytic Degradation of the Malachite Green

以热氧化法制备的TiO2/Ti薄膜电极为阳极、石墨电极为阴极、饱和甘汞电极为参比电极,设计了一种新型的双槽光电化学协同催化反应器,用离子交换膜连通反应器的两电极槽,考察了pH、孔雀绿初始浓度、连通方式等因素对降解脱色效率的影响,研究了孔雀绿的催化降解过程动力学,并根据其降解前后的紫外-可见光谱的变化,探讨了其催化降解过程.结果表明,初始浓度为30mg·L-1的孔雀绿溶液,在pH=3时,经过120min的光电化学协同催化降解,脱色率可达97.7%;孔雀绿的光电化学催化降解反应属于准一级反应;·OH不仅攻击了其分子内的强生色基团,破坏了大分子共轭体系,而且孔雀绿大分子内的芳香环或具有芳环的中间产物也被氧化降解为小分子化合物.

A novel two-compartment photo-electro-chemical catalytic reactor was designed.The TiO2 /Ti thin film electrode thermally formed was used as photo-anode,and graphite as cathode and a saturated calomel electrode （SCE） as the reference electrode in the reactor.The anode compartment and cathode compartment were connected with the ionic exchange membrane in this reactor.Effects of initial pH,initial concentration of malachite green and connective modes between the anode compartment and cathode compartment on the decolorization efficiency of malachite green were investigated.The degradation dynamics of malachite green was studied.Based on the change of UV-visible light spectrum,the degradation process of malachite green was discussed.The experimental results showed that,during the time of 120min,the decolouring ratio of the malachite green was 97.7% when initial concentration of malachite green is 30 mg·L-1 and initial pH is 3.0.The catalytic degradation of malachite green was a pseudo-first order reaction.In the degradation process of malachite green the azo bond cleavage and the conjugated system of malachite green were attacked by hydroxyl radical.Simultaneity,the aromatic ring was oxidized.Finally,malachite green was degraded into other small molecular compounds.