Removal of MTBE by Gas-Phase Photocatalytic Technology

摘要

This study investigated the feasibility of applying gas-phase photocatalytic technology to MTBErnremoval. A series of experiments for photocatalytic oxidation of MTBE were conducted in anrnannular photocatalytic reactor. Several experimental parameters including MTBE initialrnconcentrations, water vapor content, oxygen concentrations, and reaction temperatures wererntested. The experimental results showed that MTBE reaction rate increased with increasingrninfluent concentration. Lower water vapor concentration improves the photocatalyticrndecomposition of MTBE. Alternatively, water vapor would compete with MTBE for active sitesrnon TiO2 surfaces and would retard the degradation rates of MTBE as water vapor concentrationsrnwere too high. A first-order reaction for MTBE decomposition was detected while oxygenrnconcentration lower, but a zero-order reaction was observed after adsorption saturation of oxygenrnonto TiO2. It was also observed that at higher temperature, slower degradation rates wererndetected. A bimolecular Langmuir-Hinshelwood kinetic model is applied to simulate therndependence of reaction temperature on gas-phase photocatalysis of MTBE. The proposed modelrnsuccessfully explains why the MTBE photocatalytic reaction rates increase with the temperaturernfrom 30 to 120 C. The results of simulated adsorption constant (KM, KW and KO) declining withrnthe temperature but reaction rate constant (kLH) increasing with temperature verified thatrnincreasing the reaction temperature reduces the adsorption rates of MTBE, water and oxygen butrnpromotes the chemical reaction rate. This study extends our understanding about basic kinetics ofrnTiO2 photocatalytic reactions.