Studies On Photoelectrochemical Catalytic Degradation Of Dyes Wastewater

Photocatalytic oxidation is a technique for removal of pollutants from aqueous and airstreams by semiconductors such as TiO2,ZnO.And photocatalytic and electrochemical oxidation combined to achieve synergistic combination of photoelectrocatalytic technology.lt has become a new advanced oxidation Processes(AOPs),and has widely used, because of high-efficiency, low-power, wide-safety.Therefore,it is important that photocatalytic oxidation be developed.The dyes wastewater treatments in and out domestic, and photocatalytic, photoelectrocatalytic technology degradated on dyes wastewater were analyze in this article.The work principle and configuration of the photocatalytic reactor was rearched.A novel two-compartment photoelectrochemical 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.The photoelectrochemical catalytic degradation of malachite green and crystal violet dyes wastewater were investigated, and got a successful removal in this work. The experimental results shown that, during the time of 120min, the decolouring ratio of the malachite green was 97.7%, and crystal violet was 99.3%,when the initial concentration of dye solution is 30mg·L-1,the initial pH is 3.0,the cathode potential Ec=-0.60V.The degradation dynamics of malachite green in photoelectrocatalytic and the degradation decoloration and mineralization of dyes were studied.The experimental results show that, in the degradation process of malachite green,the catalytic degradation of malachite green was a pseudo-first order reaction.The catalytic degradation of dyes in photoelectrochemical reactor,decolorization occurred prior to mineralization,compared to the decolorization process, mineralization is a relatively slow process.Based on the GC/MS,FT-IR,UV,the intermediates were analyzed,the degradation pathways of malachite green in two-electrode tanks were respectively investigated. The experimental results showed that, the catalytic degradation pathways of malachite green were similar in two-electrode tanks:The double bond of molecular structure was attacked by strong oxidative hydroxyl radical,and then the malachite green was degraded by two pathways into Dimethylamino-benzophenone,4-Dimethyl aminobenzo phenone,4-Dimethyl amino-phenol and other intermediate products.Eventually, malachite green was degraded into oxalate as a small molecular organic acids,which were then mineralized into CO2 and H2O,degraded by the process such as de-methylation, deamination, nitration, substitution, addition and other reactions.