Preparation And Characterization Of Gd,Pt,ACF Modified TiO₂

With the development of global economy, environmental pollution becomes more and more serious, which has received immense attention. Porous carbon adsorption and TiO2 photocatalytic oxidation are two main methods for organic pollutants purification. For TiO2/ACF composite, activated carbon fibre(ACF) provides high pollutant-adsorbed concentration environment for loaded TiO2 photocatalyst, enhances photocatalytic rate and efficiency, retards catalyst deactivation and resolves separation problem. TiO2 photocatalyst realizes in-situ regeneration of ACF, then improves its adsorption capacity. In addition, nobal metals or rare-earth elements loaded on TiO2 surface could eliminate the intermediates pollution, then slow down the photocatalyst deactivation.In the paper, polyethyleneglycol as the template, gadolinium-doped porous titanium dioxide photocatalyst was prepared from titanium tetrachloride and gadolinium nitrate hexahydrate by acid-catalyzed hydrolysis method, then was loaded on activated carbon fibre surface by impregnation method. Platinum-doped titanium dioxide photocatalyst was prepared from titanium tetrachloride and hexachloroplatinic acid hexahydrate by photodeposition method. XRD,SEM,DRS,FTIR,GC-MS,EDS and N2 adsorption isotherm were used to characterize the obtained photocatalyst. The results were as follows:Gadolinium-doping could significantly increase the photocatalytic activity of TiO2 in UV region. When the added amount of Gd(NO3)3·6H2O was 0.10 g, the photocatalyst exhibited the highest photocatalytic activity, and phenol removal efficiency reached 79.8% within 100 min. The adsorption and photocatalysis performance of porous TiO2 was affected by the calcination temperature. The photocatalyst exhibited the best performance at 500℃. Gadolinium-doping could significantly improve the dispersion performance, inhibit the crystallite growth and agglomeration. The porous structure could significantly increase the specific surface area of the photocatalyst. Doped-gadolinium also could increase the adsorption capacity in the visible-light region.Gadolinium-doping could significantly increase the photocatalytic activity of TiO2/ACF in UV region. When the added amount of Gd(NO3)3·6H2O was 0.20 g, the composite exhibited the highest photocatalytic activity, and benzene removal efficiency reached 71.2% within 100 min. The photocatalytic activity of gadolinium-doped TiO2/ACF was also affected by dip-coating times. The composite dip-coated twice exhibited the highest photocatalytic activity for benzene removal, and remained high activity after 100 min. Gadolinium-doping could inhibit the crystallite growth, then decrease the crystallite size. Gadolinium-doped TiO2/ACF could form Ti-O-Gd bond near 540 cm-1 and Ti-O-C bond near 1060 cm-1. With the increase of dip- coating times, the specific surface area of the composite decreased. Doped-gadolinium also could slow down the photocatalyst deactivation, and no quinine compounds were detected on TG/ACF surface.Platinum-doping could significantly increase the photocatalytic activity of TiO2 thin film in UV region. When the added volume of H2PtCl6 was 0.78 mL, the photocatalyst exhibited the highest photocatalytic activity, and benzene removal efficiency reached 54.6% within 100 min. The photocatalyst remained high activity after 100 min. The increasing activity of platinum-doped TiO2 thin film at elevated temperature was concerned with Pt thermocatalyst. It is inferred that the degradation of benzene was enhanced by the combined effects of the photocatalytic and thermocatalytic property.