Study On Degradation Of Methylene Blue By Graphene/TiO₂

Photo-catalytic TiO2, as an environmentally-friendly material, has already received people’s concern because it is stable, non-toxic, efficient and has no secondary pollution and effective degradation of pollutants. However TiO2 is a wide-bandgap material, the narrow spectrum absorption range, the high recombination rate of photoelectron-hole and nanoparticles agglomerate phenomena limit its widespread application. Therefore to improve the photocatalytic property and expand the absorption spectrum of TiO2 attracted more and more attention. Graphene/titania multiplex photo-catalyst was prepared through hydrothermal method by using homemade graphite oxide and butyl titanate as precursors, the photocatalytic oxidation degradation pathway and kinetics modelof methylene blue was investigated in this paper. The research contents are as follows:(1) Graphite oxide was prepared by improved Hummers method, and composite catalyst with different graphene content was prepared by using butyl titanate and graphite oxide as precursors. The effect of doping content on the photocatalytic activity of photocatalyst was studied, and the structure and character of photocatalyst was carefully studied with SEM, TEM and XRD. The results showed that the degradation effect is the best when the graphene content of photocatalyst was 5%. The anatase TiO2 was obtained during hydrothermal process, which was approximately 25 nm in diameter and showed good dispersion. The composite catalyst could respond to visible light. Methylene Blue could be degraded by photocatalytic reaction for 60 min under UV light.(2) The composite catalyst was used to degrade methylene blue simulation dye effluents to evaluate the reclamation rate of photocatalyst and the optimum treatment condition. The results showed that the reusable photocatalyst exhibited excellent stability. The optimum conditions were obtained: simulation dye concentration 20mg/L, photocatalys quantity 100 mg, response time 60 min.(3) The photocatalytic oxidation degradation pathway of methylene blue was investigated by spectral analyses. The results showed that hydroxyl radicals firstly attacked the N-S heterocycle chromophore group of dye molecules, and the intermediate products were continued to be degraded into small-molecule products after a series of reactions, such as CO2 and H2 O.(4) The kinetics model of methylene blue simulation dye effluents by composite catalyst was investigated. The results showed that the photocatalytic degradation of methylene blue was according with the first-order model:The innovations in this paper cover the following:first of all,to improve the photocatalytic property and expand the absorption spectrum of Ti O2, grapheme was added into Ti O2. Secondly it was the first time to use UV、IR、GC-MS to analyse the intermediates and end product which degraded from methylene blue. The photocatalytic oxidation degradation pathway of methylene blue was inferred, which could supply theoretical basis and technical route for exploring degradation rule of dye wastewater.