Preparation, Characterization And Visible Photocatalytic Properties Of Silver Doped Nano-TiO₂and Loading On Activated Carbon

TiO2as an excellent photocatalyst is widely used in the field of environmentalpollution treatment and purification.But the practical application of nano-TiO2hassome disadvantages, such as the low quantum efficiency, narrow spectral response,poor treatment for low concentration organics and nano-TiO2powder agglomerateeasily and is hard to separate and recycle. In order to solve above prombles, this paperprepares the Silver doped nano-TiO2photocatalyst (Ag+-TiO2) by hydrothermal, andstudying the improvment effect and modification mechanism of Ag+-TiO2catalyticactivity in visible light by doping Ag+; To further enhance nano-TiO2photocatalyticactivity, Silver doped nano-TiO2photocatalyst is loaded on activated carbon(Ag+-TiO2/AC) by dipping-hydrothermal method. The target pollutant is methylorange (MO), Ag+-TiO2/AC visible light catalysis degradation is studied in a externalenvironmental factors, including initial concentration of MO, catalysts, plus anoxidant, sources and reuse. The synergy effect between adsorption and photocatalyticof Ag+-TiO2/AC was quantified, and the mechanism of Ag+-TiO2/AC compositephotocatalytic degradation was analyzed. The main research work was as follows:(1) Ag+-TiO2photocatalyst was prepared by hydrothermal. TEM and XRD showthe samples were assembled by5~20nm nano-anatase TiO2, UV-Vis spectra displaysthat the appropriate amount of Silver doped leds TiO2absorption spectra red-shifted,and has a strong absorption band in the visible region.(2) Ag+-TiO2/AC composite was prepared by impregnation-hydrothermal methodand the best preparation conditions are: titanium content was5mL, hydrothermaltemperature was200℃, reaction time was8h, and doping ratio of Ag+was0.1%.TEM indicated that TiO2particle size were5~10nm. XRD showed that TiO2wasanatase phase. FT-IR spectrum showed the composite still retains the originalActivated Carbon surface functional groups such as-OH, C=O, CO, and appears Ti-Ovibration peaks.(3) The optimum doping ratio of Ag+-TiO2is0.25%. The kinetics of Ag+-TiO2photocatalytic reaction fitted the Langmuir-Hinshelwood model, the apparent reactionrate constant of the visible photocatalytic degradation of0.25%Ag+-TiO2was3.9times of pure TiO2. Due to just the right amount of Ag+doped TiO2, in addition tohave Ag+doped into TiO2lattice, and the Ag+no doped will deposit on the surface of TiO2with Ag atom clusters.(4) The kinetics of Ag+-TiO2/AC photocatalytic reaction fitted well theLangmuir-Hinshelwood model, the apparent reaction rate constant of the visiblephotocatalytic degradation of Ag+-TiO2/AC was7.5times of pure TiO2.The synergyeffect between adsorption and photocatalytic increases first and then decreases withreaction times. Due to the continuing synergy effect between high adsorption capacityactivated carbon and photoactive Ag+-TiO2, the degradation of low concentration oforganic pollutants were obviously improved.