Preparation And Research Of Mixed-phase TiO₂ Photocatalysts By Molecular-imprinting Method

Large amounts of industrial organic wastewater are produced and discharged into river and other natural waters every year in China causing immense pressure to the nature.In recent years,PPCPs?pharmaceuticals and personalcare products?,resistance genes,xenoestrogens and other pollutants of low concentration but high toxicity are discovered frequently from treated sewage and rivers that hazards our aqueous environment and human health.Hence,developing methods to extract such contaminants economically and with high efficiency is of greatly practical significance.Among various alternatives,employing photocatalytic technique to decompose pollutants under ultraviolet or visible light irradiation is the most favorable method for its complicity and low cost.Among various photocatalysts,titanium dioxide is the most popular one for its stability,high efficiency?especially mixed-phase TiO2?and cheapness since most other efficient catalysts are either toxic or prepared from noble metal.This thesis is aimed to give possible solutions to overcome this method's three shortcomings:almost no selection for differed pollutants,low utilization efficiency of visible light and quick recombination of photoinduced holes and electrons.Molecular imprinting is introduced to strengthen the absorption of specific aimed pollutant molecules.Except for that,mixed-phase?anatase-rutile?TiO2 with large specific areas is prepared after which metallic doping and magnetic loading is applied and studied.This paper includes the following contents:?1?Firstly,mixed-phase?anatase-rutile?TiO₂ catalysts are prepared by one-step solvothermal method.Then,as the imprinting and targeting contaminant molecules,DNBP?2-Sec-butyl-4,6-dinitrophenol?is added during the preparing process.After researching the optimal experimental conditions is the characterization of produced samples by XRD,SEM,TEM,UV-vis,N₂ adsorption-desorption isotherm and isoelectric point analysis.?2?Using xenon lamp as the light source and DNBP solution as the target pollutant to study the photodegradation ability of these two kinds of as-prepared TiO₂ catalysts.The results shows that the absorption and photocatalytic degradation ability of MIP-samples?molecular-imprinting-product?is higher than their non-MIP counterparts.Moreover,when the polluting solution is constituent of tow contaminants,this condition also occurs.?3?Metallic doping and magnetic loading is managed to expand the range of photoresponse and realize the recycling of catalysts.Firstly,element Fe or La is added via the solvothermal preparation process and by this way Fe³⁺and La³⁺doped TiO₂ are produced.Secondly,Fe₃O₄ water-based magnetic fluid are prepared and used to give magnetism to samples.After the characterization by XRD,SEM,TEM,UV-vis,N₂ adsorption-desorption isotherm and VSM,it is found that doped catalysts have a larger range of light response so that they can utilize more visible light and the samples can be magnetic.?4?The adsorption capacity and photocatalytic performance of modified catalyst are tested using the same DNBP solution under the xenon lamp irradiation.The results displays that the doping method can promote the photodegradation efficiency.