Study On Photocatalytic De-gradation Of Gaseous1,2-dichlorobenzenes On Carbon Absorption Material-doped Nano-TiO₂

The part of municipal solid wastes (MSW) dealing with incineration has been increasing in the last ten years. There are a lot of works to do in China for executing the Stockholm Convention on Persistent Organic Pollutants. The dioxins control technologies on incinerators become more and more important. The emission of dioxins of incinerators can be reduced to meet standards using activated carbon (AC) injection, but secondary pollution appears after this technology.1,2-dichlorobenzenes(1,2-DCBz) is selected as the substitute of dioxins in this paper. Photocatalysts of activated carbon-supported TiO2(TiO2/AC) and multi-walled carbon nanotubes-supported TiO2(TiO2/MWNTs)were prepared by sol-gel method.The photocatalytic effects of these photocatalysts and influences of some factors on the photodegradation were investigated. The major parts are as following:(1) The review first describes the principles of photocatalytic destruction by semiconductors and then focuses on the mesns of modification of TiO2.Aiming at solving the pollution problems of urban solid waste incineration of our country, the current major dioxin controlling technologies and the problems of them are investigated.Based on previous studies,feasibility and credibility of using chlorobenzenes as a substitute for dioxins are confirmed. In order to solve the shortcomings of conventional TiO2photocatalysts in practical application,research direction of modifying TiO2photocatalysts with porous adsorption media has been identified.(2) Photocatalysts of activated carbon-supported TiO2(TiO2/AC) was prepared by sol-gel method.Nitrogen adsorption, X-ray diffraction(XRD), Scanning electron microscope(SEM) were used to obtain the performance parameters of TiO2/AC catalysts.Adsorption properties of gaseous1,2-DCBz on photocatalysts at150℃without light were studied and the results showed that adsorption properties of gaseous1,2-DCBz on different photocatalysts were basically proportional to the specific surface area and had a great relationship with pore structure of photocatalysts. It was proved that TiO2/AC catalysts had a synergetic effect of AC adsorption and TiO photocatalysis on the degradation of gaseous1,2-dichlorobenzene by comparing the photocatalytic performanceof commercial P25catalyst and TiO2/AC catalysts.(3) Catalyst of CoxMg1_xMoO4for production of carbon nanotubes was prepared using a simple combustion method.Multi-walled Carbon nanotubes grew on powered particles of CoxMg1_xMoO4catalysts through cracking methane in tube furnace at1000℃using chemical vapor deposition method(CVD). Photocatalysts of multi-walled carbon nanotubes supported TiO2(TiO2/MWNTs) was prepared by sol-gel method.Nitrogen adsorption, X-ray diffraction(XRD), Scanning electron microscope(SEM) and Transmission electron microscope were used to obtain the performance parameters of TiO2/MWNTs catalysts.Carbon nanotube had good adsorption properties owing to its special tubular structure and large specific surface area,and meanwhile carbon nanotube itself had a certain absorption and degradation ability.By comparing the degradation effects of TiO2catalysts and TiO2MWNTs on gaseous1,2-DCBz,it proved that the adding of carbon nanotubes to the photocatalysts greatly improved the performance of photocatalysts.