Role of the Cathode in a Novel Photo-Electro-Chemical Catalytic Reactor

A novel photo-electro-chemical catalytic reactor with single/double-tank was designed. TiO2/Ti thin film electrode was used as photo-anodes, graphite as cathode and a saturated calomel electrode (SCE) as the reference electrode in the reactor. The efficiency of photo-electro-chemical catalysis was enhanced because the target pollutant was degraded not only titanium dioxide electrode in anodic tank, but also hydrogen peroxide through reducing dissolved oxygen with graphite electrode in catholyte. Malachite green (MG) and crystal violet (CV) were degradated effectively in these two reactors. The degradation efficiency of the double-tank reactor is superior to that of single-tank reactor and its apparent reaction rate constant is twice or more of than that of the single-tank reactor, which was result from the higher concentration of H2O2 in the double-tank reactor. In the single-tank reactor, H2O2 generated during cathodal reaction diffused to the anode and was consumed, while it could be prevented in the double-tank reactor. Under the conditions of cathodic potential Ec at-0.6V, initial solution pH at 3.0 and initial solution concentration 30 mg·L-1, the catalytic degradation of MG and CV were both pseudo-first order reactions.