Preparation Of Dye-sensitized Photocatalyst And Its Visible-light Photocatalytic Activity

Nano-sized TiO2 has been extensively used for degradation of water pollutants due to its non-toxicity,low-cost,high photocatalysis efficiency and chemical stability.Unfortunately,its application is limited by its wide band gap(3.2 eV),thereby only responding to UV light which accounts for a small fraction(5%)of the sun's energy compared to visible light(45%);and its rapid charge recombination of the e--h+ pairs.Additionally,it is well known that the morphologies and microstructures could exert a strong influence on the photocatalytic activity of TiO2.Therefore,the surface modification and dye sensitization of the as-prepared TiO2 was well established to improve its visible light photocatalytic activity in this thesis.And the main conclusions are as follows:(1)The Tiron-TiO2 was prepared via the 1,2-dihydroxy-3,5-benzenedisulfonic acid-disodium salt(Tiron)as chelate sensitizer.The photocatalytic activity of Tiron-TiO2 was examined by degradating 10 mg/L of methylene blue(MB)under visible light,in which its effecting factors such as nTiron:nTiO2,pH and reaction time were invetigated in detail.The results showed that the optimum InTiron;:nTiO2,pH and reaction time were 0.5,1 and 6 h,respectively.Under above conditions,the Tiron-TiO2 exhibited approximately spherical structure with the average diameter of 300-400 nm and matched well with anatase.Under Xe lamp irradiation within 120 min,more than 88.1%of MB was removed and the Tiron-TiO2 photocatalyst can efficiently degrade MB without significant deactivation after 4 recycled(degradation efficiency remains 80.0%).Moreover,the degradation efficiency of chloramphenicol(CAP),sulfamethazine(SMT)and lomefloxacin(LFC)were 63.9%?77.9%and 74.9%respectively.(2)hTiO2 was prepared by one-step template-free method,the photocatalytic activity of hTi02 was examined by degradating 10 mg/L of methylene blue(MB)under UV light,in which its effecting factors such as n-Ti(sO4)2:nNaF,hydrothermal temperature and time were investigated in detail.The results showed that the optimum nTi(SO4)2:nNaF,hydrothermal temperature and time were 1:1,140 ? and 14 h,respectively.Under above conditions,the hTiO2 exhibited hollow microspherical structure with the average diameter of 1.5-2 ?m,which were composed of 40-50 nm nanoparticles,and matched well with anatase.Under high pressure mercury lamp irradiation within 80 min,all of MB was completely removed.On the basis of successful preparation of hTiO2,visible-light assisted PS-Tiron-hTiO2 was obtained by combination of surface modification and dye-sensitization with Tiron and Phenosafranine(PS).Under Xe lamp irradiation within 120 min,the photocatalytic efficiency on MB was up to 99.6%and the PS-Tiron-hTiO2 photocatalyst can efficiently degrade MB without significant deactivation after 4 recycled(degradation efficiency remains 90.0%).Moreover,the degradation efficiency of chloramphenicol(CAP),sulfamethazine(SMT)and lomefloxacin(LFC)were 82.1%?91.3%and 100%respectively.(3)Pyrocatechol Violet(PV)sensitized TiO2(PV-TiO2)photocatalysts were successfu-lly prepared by in-situ solvothermal method.The photocatalytic activity of Tiron-TiO2 was examined by degradating 10 mg/L of methylene blue(MB)under visible light,in which its effecting factors such as the amount of sensitizer,hydrothermal temperature and time were investigated in detail.The results showed that the optimum amount of sensitizer,hydrothermal temperature and time were 0.1%,120 ? and 6 h,respectively.Under above conditions,the as-prepared PV-TiO2 exhibited approximately spherical structure with the average diameter of 450-800 nm composed of 40 nm nanoparticles and matched well with anatase.Under Xe lamp irradiation within 120 min,the degradation rate of MB was 94%and the PV-TiO2 photocatalyst can efficiently degrade MB without significant deactivation after 4 recycled(degradation efficiency remains 90.0%).Moreover,the degradation efficiency of CAP,SMT and LFC were 66%?67.6%and 62.9% respectively.