Studies On Photo-electro-chemical Catalytic Decolorization And Degradation Of Dyes In Water

The article has summarized discharges of dye wastewater and its hazards and treatment methods, especially focused on assessment of advanced oxidation technologies applied to degradation of dye wastewater. Based on predecessors' photo-electro catalysis as well as our research group's former study on photo-electro-chemical catalysis, a one-chamber photo-electro-chemical reactor has been developed. The decolorization and degradation effects of reactive red X-3B, acid brilliant scarlet GR, fuchsin basic, direct fast black G, methyl orange by the reactor have been studied, some factors affecting the catalytic performance of the reactor have been evaluated. Details are shown as below.The study has designed a one-chamber photo-electro-chemical reactor. A TiO₂ thin film (made by hot oxidation method) works as the anode, high purity graphite works as the cathode, and a saturated calomel electrode (SCE) as reference electrode. A bias-voltage between two electrodes is supplied by a potentiostat in the experiment. Under the conditions of UV irradiation and constantly pumping air into the reactor, the degradation and decolorization of reactive red X-3B have been studied. Main factors affecting the catalytic performance of the reactor such as cathodic potential, pH value and supporting electrolyte have been evaluated. As data show, TiO₂ thin film is very reactive under UV irradiation, photo-generated current is so strong that the life of the holes are obviously extended; though pumping air into the reactor, dissolved oxygen is maintained, high purity graphite can generate hydrogen peroxide, as a result, the UV/H₂O₂ catalytic system is established. The anode and the cathode have the ability to produce oxidation effect in a single chamber, consequently, the goal of "one chamber, two electrodes and double effect" comes true. When supporting electrolyte CNa2so4=1000mg ? L^-1, initial pH value is 4.0 and cathodic potential -E_C=0.6V, the discoloring rate of reactive red X-3B solution(initial C=25mg ? L^-1) reaches 79%, and residual mass concentration remains only 5.2 mg ? L^-1. Compared to photo-catalytic reactor, oxidation effect is remarkably enhanced. The article systematically studies the influences of factors such as cathodic potential, pH values, electrolyte concentration,...