Photocatalytic Degradation Of Gaseous Toluene,P-xylene And TCE By Modified-bentonite/TiO₂

With the development of the decoration, indoor air pollution problem is increasingly serious, and presently it shows the characteristics of multi-source, major changes in concentration, complex composition. Existing studies generally focused on single-component pollution. less multi-component gas, so it has theoretical and practical significance to study on the purification of two or more kinds of indoor air pollutants. The combination of adsorption and photocatalytic method is currently one of the most promising treatment technologies among the indoor air control technologies. Therefore, in order to get the mutual relations between the photocatalytic degradation of multi-component, and fill the deficiencies in this areas, this thesis selected the typical indoor VOCs, toluene, p-xylene and trichloroethylene together, to study about the interaction of the photocatalytic degradation of indoor multi-component pollutants by composite photocatalyst modified-bentonite/TiO2.In this study, modified-bentonite/TiO2composite photocatalyst was prepared. Photocatalytic degradation of typical VOCs occured under the environment of controlled temperature and humidity simulate cabin. The influence of the photodegradation and the bentonite catalytic to the adsorption-photocatalytic degradation of pollutants was dicussesed. The ideal proportioning of sorbent and catalysis was reached, and the influence of the ratio of the long and short alkyl chain length surfactants was studied.The interaction mechanism between trichloroethvlene and toluene was seriously studied, focusing on the impact of the initial degradation rate and the2h degradation rate of toluene. The influence of initial concentration and ambient temperature of the photocatalytic degradation of p-xylene by P25was discussed, and the interaction mechanism between trichloroethylene and p-xylene was reached. The experimental results showed that:(1) It verified that too little or too much of the water molecules were all not beneficial to the photocatalytic degradation of p-xylene by P25. When the relative humidity was45%, the photocataltic degradation of p-xylene came to the best effect by P25, which had nearly20%better than the high humidity.(2) With the increasing of the xylene concentration, the degradation rate of p-xylene decreased and then kept stable.(3) The presence of trichlorethylene had a significant promoting effect on the photocatalytic degradation of p-xylene and toluene. The photocatalytic degradation of p-xylene and toluene rate increased significantly when added trichlorethylene to the reaction system. The more amount of trichlorethylene, the photocatalytic degradation rate of p-xylene and toluene increased more obviously. The degradation rate of p-xylene and toluene all reached above90percent with the presence of trichloroethylene.(4) The initial and final degradation rate of toluene by the composite catalyst performed improvement fistly and then suppression with the addition of adsorbent dosage, which achieve the best state when the adsorbent and catalyst ratio of1:1.(5)The ratio of TMA and CTMAB also affected the photocatalytic degradation of the mixture of p-xylene and trichloroethylene. When the ratio of TMA:CTMAB is1:1. the degradation rate of p-xylene and trichloroacetic were all up to the best.(6) The degradation of toluene lonely, toluene and trichloroethylene compound pollution by modified-bentonite/TiO2is better than niked TiO2.