Photocatalytic Degradation Of Industrial Toluene Gas In ACH/TiO₂ Nano Photocatalytic Network

Volatile organic compunds (VOCs), which had serious influence on human production and life, is one of the main air pollutants, the prevention and control of VOCs had also become the hottest issuse in recent years. Nano-TiO2 photocatalytic degradation technology is a new economic and green pollution control method for VOCs removal, compared with absorption, adsorption or biofiltration. However, nano-TiO2 photocatalyst has shortcomings, e.g. poor adsorption capability, low contacting possibility with pollutant molecules and nano particles easy to loss, so the development of technology to fix photocatalyst on supports will be a key in the process of solving this problem.The ACH/TiO2 nano photocatalytic networks with different contents of TiO2 were prepared by impregnation method in this paper, with high surface area, high flux and small pressure drop activated carbon honeycomb used as carrier and high photocatalytic activity P25 TiO2 used as photocatalyst. The industrial toluene gas was generated by self-designed device, experiments on photocatalytic degradation of toluene gas in a self-made fixed photocatalytic reactor were carried out. Besides, nitrogen adsorption-desorption isotherms, XRD and SEM test methods were taken. The research of adsorption performance on ACH and ACH/TiO2 was investigated, at the same time the orthogonal experiments were done to examine three different influence factors, different contents of TiO2, toluene gas initial concentration and gas flow rate. In order to investigate the effects of toluene gas initial concentration, gas flow rate, the reactor internal humidity and temperature on photocatalytic degradation performance, evaluation of the degradation of toluene gas by a certain commercial ACH/TiO2 photocatalytic network was done.The results showed that the adsorption performance of ACH/TiO2 did not changed by impregnation method, ACH used as carrier could increase the range of toluene gas concentration. The degradation rate is not high for pure nano-TiO2 particles, while it can continue to efficiently degrade toulene gas. The results indicated that ACH and TiO2 had a good synergistic effect. In the experiments of degradation of toluene gas using self-made ACH/TiO2 photocatalytic network with TiO2 mass fraction 15.5%, the optimum conditions were ACH/TiO2-Ⅲ、240 mg/m3、1 L/min, the degradation rate was 90%. Using self-made photocatalytic reactor to investigate the commercial photocatalytic network, the effect of degradation efficiency on toluene initial concentration, gas flow rate, the reactor internal humidity and temperature were studied, finally the optimum conditions is TiO2 mass fraction is 12.5%±1%, water content is 21.5%, toiuene initial concentration is 410 mg/m3, gas flow rate is 1L/min, the reactor internal humidity is 30% and temperature is 80℃.The whole degradation process of toluene gas in self-made ACH/TiO2 was studied. The results showed that the degradation of toluene gas went through three paths:ACH active sites adsorb toluene molecules, photocatalytic oxidation of toluene by TiO2 under the condition of UV lights and desorption. The kinetics of toluene degradation is neither a zero order reaction, nor a first order reaction, but within the first 40 minutes its dynamic reaction was in line with the first order kinetics.