Preparation Of Titanium Dioxide Whiskers And Application Of Photocatalytic Wastewater Treatment

It is well-known that photocatalytic technique of nano-semiconductor is suitable to degrade organic pollutants. However, there are many problems in large-scale application, which make photocatalytic technique in wastewater application stagnant. Three main possible reasons could account for this phenomenon. One possible reason is that it is hard to separate TiO2 nanoparticle with high photocatalytic activity from the system. Another possible reason is that it is hard to prepare the photocatalyst cheaply in large scale. The third possible reason is that it is hard to solve the problem about magnification in industrialization process and to reduce the cost of purifying wastewater.In order to solve the above problems, our research group did a lot of research. Firstly, the K2Ti4O9 whisker was taken as the precursor and TiO2 whisker was obtained by ion-exchange method. The size of the TiO2 whisker is about micron and it has nanostructures. The main purpose of this thesis is to investigate the method for large-scale production of high quality TiO2 whisker and its applications in photocatalytic degradation of organic substances in wastewater.For the improvement of titanium dioxide whisker preparation method, a new hydration kinetics model, which is suit for large-scale production, is proposed. The control variables in the new model are the initial hydration ratio and pH value of solution. Therefore, we could avoid measuring the concentration of K+ ion by ISE with certain amount of KC1 added in the solution. Finally a controllable and optimal approach for the synthesis of TiO2 whisker was presented. The concentration of HCl acid is lmol/l. Ilydratcd 3 times, the amount of water 10 times, 20 times, 30 times. Then the high quality TiO2 whisker was obtained, among which the content of K element is less than 0.5% (wt%).In application about the objective the printing and dyeing wastewater and drinking water purifying were mainly studied. Methyl orange and chloroform were taken as the study objectives for printing and dyeing wastewater and drinking water, respectively. The photocatalytic activity of glycerine modified TiO2 whisker to degrade methyl orange is prior to P25. However, the stability of the photocatalyst decreases after two degradation times. Modified by Pt doping, TiO2 whisker's both photocatalytic activity and stability were improved. Ninety eight percent chloroform could be degraded by the 0.5% Pt doped TiO2 whisker which was prepared using light reduction deposition. After the catalyst was repeated to use 8 times, above 90% chloroform could still be degraded. So, the modified TiO2 whisker will be promisingdealing with wastewater in real practice.A flow photocatalytic reactor based on TiO2 whisker is established, which is above 5 times efficiency than a batch one in the same conditions. Furthermore an apparatus dealing with 200 tons wastewater per day was designed and the capacity to deal with waste water and the degradation could be automatically controlled using series connection and parallel connection reactors.