Study On The Degradation Of X-3B By Microwave Assisted Photocatalysis Method

Photocatalytic oxidation is a novel method for wastewater treatment. There are some disadvantages for common TiO₂ catalyst, such as low photocatalytic quantum efficiency, difficult separation of TiO₂ and wastewater system and less utility of sunlight. In this study, some absorbent materials such as rectorite, pumice, granular activated carbon were used as carrier of immobilized TiO₂ catalyst. The supported TiO₂ was made by sol-gel method and X-3B was chosen as a target contaminant. Then the microwave assisted UV decoloration (MW/UV) and microwave assisted UV/TiO₂ photocatalytic decoloration (MW/UV/TiO2) were used to decolor azo dyes respectively. The mechanism of decoloration were investigated. The main results were as follows: (1) The sequence of the decoloration rates of X-3B for different systems was MW/UV/TiO₂> MW/UV > UV/TiO₂>UV. The decoloration was enhanced by MW because of the significant synergistic effects between MW and UV,TiO₂ and H₂O₂; (2) During the concentration of 100mg/L to 1000mg/L, the pseudo-first-order decoloration kinetics of X-3B were observed for both MW/UV and MW/UV/TiO₂. Decoloration rate can be significantly enhanced by the increase of light intensity or adding of H₂O₂, acid or alkaline; (3) The carrier of TiO2 film made of some absorbent materials could enable the immobility of TiO₂ as well as enrich the pollutants on the surface of the photocatalyst, which enhanced the efficiency of photocatalysis. In addition, MW could facilitate the regeneration of photocatalyst and improve the life of the photocatalyst. (4) The mechanism for the decoloration of X-3B involves both photocatalytic oxidation and direct photolysis.