Preparation Of TiO₂Cooperated With Ionic Liquid And Performance And Mechanism Of Degradation Of CN^-and Phenol

Industrial wastewater containing inorganic and organic pollutants has always been a main environmental concern throughout the world.The TiO2photocatalyst has been the focus of water purification processing studies because of its non-poisonous feature high activity,security,stability,low cost and other advantages.Electron-hole pairs will be generated upon excitation by light with energy equal to or greater than the bandgap of TiO2.Since the strong oxidative power of the photogenerated holes made it possible to oxidize most of the organic pollutants and to transform some of the toxic inorganic pollutants into harmless forms as well,photocatalysis of TiO2is significant for environmental remediation.Based on the distinct characteristics of ionic liquid in preparation of micro/nano materials,the ionic liquid was used as the medium in preparation of TiO2for modification.It is hoped that the inspire light width could be widened,the surface properties and crystallization type could be improved and the visible utilization and quantum efficiency could be enhanced.The CN-and phenol were the main environmental pollutants from industrial waste water which recognized as the strong toxic and hard-degradation substances.This research aimed at removal of CN-and phenol respectively from water using photocatalysis and modified-Ti02and metal ions doped modified-TiO2,that were prepared by a sol-gel method which use [Bmim]PF6as reaction medium and microwave-assisted means.The oxidation and reduction capability of the TiO2powder have been studied comprehensively from some important factors of the photocatalytic CN-and phenol decomposition in the reaction and the immobilization of TiO2was also studied. With the help of X-ray diffraction(XRD),SEM,UV-Vis,after a series of photocatalytic experiments of degradation of CN" and phenol with using the new photoreactor which was built by ourselves,we studied many facators affecting the photocatalytic activity of TiO2powders.More information was provided to optimize TiO2powder photocatalyst and its may be helpful for further study of photocatalytic mechanisms.Some results are as follows.1) The modified-TiO2was prepared by a sol-gel method which use [Bmim]PF6as reaction medium and microwave-assisted means and had an equality shape and high dispersion.The TiO2powder was made up mauly by anatase type and its absorption range of light was expanded to450nm.The sol-gel method with microwave-assisted means was studied and the adding amount of [Bmim]PF6was also investigated.The best ratio is n[Bmim] PF6:nTTIP=0.4:1. 2) The oxidation and reduction capability of the modified-TiO2had been studied comprehensively from some important factors of the photocatalytic CN-decompose in the reaction The effects of various operational parameters such as pH, catalyst concentration, CN-concentration, the quality proportion of anatase type and rutile type and illumination condition on the photocatalytic degradation of CN-were investigated. After10hours8w UV irradiation, the results showed that the pH of the aqueous solution was4,the initial concentration of CN-was60mg/L;,the quality proportion of anatase type and rutile type was1:1,ratio of the solution was300mgTiO2/L,800cm(?)illumination area, under such conditions,the degradation rate could be enhanced to about100%when the modified-Ti02was used.3) The oxidation and reduction capability of the modified-TiO2had been studied comprehensively from some important factors of the photocatalytic phenol decompose in the reaction. The effects of various operational parameters such as pH, catalyst concentration, phenol concentration, the quality proportion of anatase type and rutile type and illumination condition on the photocatalytic degradation of pheno were investigated. After20hours8w UV irradiation, the results showed that the pH of the aqueous solution was4,the initial concentration of phenol was50mg/L;the quality proportion of anatase type and rutile type was1:2,ratio of the solution was300mgTiO2/L,800cm2illumination area, under such conditions,the degradation rate could be enhanced to about100%when the modified-TiO2was used.4) The metal ions doped modified-TiO2was prepared by a sol-gel method which use [Bmim]PF6as reaction medium and microwave-assisted means and doped by Cu2+,Ni2+,Pb2+,Zn2+,Fe3+. In the studies of light absorption performance, the photon exeited wavelength of metal ions doped modified-TiO2powder were broaden to visible light.The oxidation and reduction capability of the metal ions doped modified-TiO2had been studied comprehensively from some important factors of the photocatalytic CN-and phenol decompose in the reaction.5) Through the experiments it could be discovered that doped with Cu2+could enhance the degradation rate of CN".TiO2photocatalysts co-doped with Cu2+can gain the best degradation efficiency when the doping quality is0.5%.After10hours indoor nature light photocatalytic reaction,the degradation rate of CN-could achieve to about80%.Through the experiments it could be discovered that doped with Fe3+could enhance the degradation rate of phenol.TiO2photocatalysts co-doped with Fe3+can gain the best degradation efficiency when the doping quality is0.5%.After20hours indoor nature light photocatalytic reaction,the degradation rate of phenol could achieve to about81.3%. 6) The TiO2coated on natural zeolite,dauk and modified serpentine were prepared by sol-gel method.The TiO2/natural zeolite composite,TiO2dauk composite and TiO2/modified serpentine composite were charaeterized by XRD,and SEM.The laboratorial results showed that the natural zeolite and modified serpentine could consequently enhances the photocatalytic activity of TiO2while dauk could not.7) The reaction mechanisms of TiO2preparation process which using [Bmim]PF6as reaction medium and doping with metal ions were studied.The mechanisms and reaction kinetics of photocatalytic degradation of CN-and phenol were preliminary discussed and analyzed.The results above maybe helpful to design and construct photocatalyst which using to decompose CN-and phenol with high activity and provide certain theoretical foundation and technical reference for practical degradation of water pollution.