Photoelectrocatalytic degradation of malachite green (MG) under visible light irradiation with TiO 2 -film electrode has been investigated to reveal the mechanism for TiO 2 photocatalytic degradation of dyes. The supported TiO 2 electrode was prepared in laboratory and detected by scanning electron micros-copy and X-ray diffractometry. We have examined the degradation kinetics, change in degradation rate of MG and photocurrent change with the bias potential, voltage-induced adsorption of dyes, accumu-lation of electrons in the TiO 2 electrode, effect of various additives such as benzoquinone (BQ), and formation of active oxygen species by UV-visible spectroscopy, TOC and spin-trap ESR spectrometry. It was found that the dyes could controllably interact with TiO 2 surface by external bias and charge of dyes. The cationic dye MG underwent efficient mineralization at negative bias under visible light irradiation, but N-dealkylation process predominated at positive bias under visible light irradiation. At negative bias of -0.4 V vs SCE, the O2 •-and dye •+ were formed simultaneously at the electrode/electrolyte interface during degradation of cationic MG. Experimental results imply both the superoxide radical and the dye cationic radical are essential to the mineralization of the dyes under visible-light-induced photocatalytic conditions. TiO 2 electrode, photocatalysis, MG, mineralization, mechanism Citation: Yang J, Dai J, Zhao J C, et al. Mechanism of photocatalytic degradation of dye MG by TiO 2 -film electrode with cathodic bias potential.
The water absorbent resin is a new type of polymer plugging materials developed in recent years, the water swelling with certain viscoelastic gel, with a certain intensity, strong water retention, salt resistance and stability. Polymerization aqueous solution of acrylic acid (AA), acrylamide (AM) as the experimental materials, the choice of a controllable expansion sealing agent the KP to determine the formula developed by the sealing agent, and has good suction rate, anti-performance of salt and water retention.
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