| Semiconductor nano materials have been widely used in chemical, pharmaceutical, electronics, military, aerospace and other fields due to its unique electric, optical, magnetic properties, which have been one of the most popular research materials at present. Among the semiconductor materials, CdSe, CdS, TiO2are the most in-depth study because of the excellent photoelectric properties. But, the CdSe and CdS photocatalysts are easily photocorrosion during the process of photodegradation, and the TiO2is limited by the visible light, so it is need to modified the photocatalysts to improve the photocatalytic activity.In this paper, the CdSe, CdS and TiO2were modified by loading, compositing, etc to construct the composite photocatalyst to increase the photocatalytic activity. The samples were characterized with XRD, UV-vis DRS, FT-IR, TEM, XPS, SEM and PL.This paper mainly includes the following three aspects:1. Preparation and research on the mechanism and photodegradation of antibiotic with CdSe and their composite photocatalysts.(1) CdSe nanocrystals were synthesized with3-Mercaptopropionic acid as a stabilizer by hydrothermal method. The structure and properties of CdSe quantum dot will be characterized by XRD, UV-vis DRS, FT-IR, TEM and XPS data. According to the photocatalytic degradation of Cefalexin wastewater, the effect and mechanism of various conditions were discussed. The results show that:theCdSe quantum dots with cadmium chloride as the Cd source, in the molar ratio of Se/Cd to5/4have the highest photocatalytic activity and the degradation ratio of Cefalexin wastewater reached70.34%under the UV light.(2) The CdSe-Bi2WO6composite photocatalyst was synthesized by multi-step hydrothermal method via selecting the CdSe nanocrystals as a sensitizer, which is applied to the research on photocatalytic degradation of Ttetracycline wastewater under visible light. The prepared photocatalyst was characterized by XRD, SEM, PL and UV-vis DRS. The content of CdSe has certain effect on the photocatalytic activity of CdSe-Bi2WO6composite photocatalysts. When the load of CdSe was15%, the photocatalytic activity was highest. The CdSe-Bi2WO6composite photocatalyst has good stability and keep high activity after5times of repeated experiments.2. Preparation and Research on the photodegradation of antibiotic with CdS composite photocatalyst.(1) Carbon nanotubes (CNTs) as a carrier, the CdS/CNTs composite photocatalyst were synthesized by hydrothermal method. The structure and performance of photocatalysts were characterized by XRD, TEM, Raman, UV-vis, DRS, PL etc, and discussed the activity and kinetics of photodegradation. From the results,95%-CdS-5%-CNTs conposite photocatalyst has high photocatalytic activity, the degradation ratio of Tetracycline is81.2%. Moreover, the process of degradation adhere to the first-order kinetic.(2) CdS-WO3photocatalyst with heterojunction structure were prepared via the hydrothermal method. The structure and properties of the photocatalyst were characterized by XRD, SEM, STEM, TEM, UV-vis, DRS, PL, etc. The photocatalytic degradation experiments on Ciprofloxacin antibiotic solution was tested. Effects on the photocatalytic activity of different concertration of CdS was investigated and the results show that30%-CdS-70%-WO3composite photocatalyst on degradation of Ciprofloxacin waste water reached88.85%, which is3times of pure WO3.3. Preparation and Research on the photodegradation and selection of antibiotic with TiO2composit photocatalyst(1) The Cl doped TiO2composite photocatalyst were prepared via a solid-state method with NaCl as the source of chlorine. The crystal phase, surface structure, morphology, doped and optical properties of the photocatalysts were characterized by XRD, SEM, TEM, XPS, UV-vis, DRS, etc. Through doped with different ion and synthesised with different calcination temperature, we can find that the photocatalytic activity of Cl doped TiO2is highest and the degradation ratio of Ciprofloxacin antibiotic waste water reached87.71%.(2) The surface molecular imprinted Cl doped TiO2photocatalyst was synthesized by surface molecular imprinted technology using Ciprofloxacin (CEP) as the molecular template. The acrylamide (AM), Trimethylolpropaneacrylate (TMPTA), and2,2-azobisisobutyronitrile (AIBN) were considered to functional monomer, cross-linking and initiate, respectively. The structure, morphology and properties of the imprinted photocatalyst were characterized by XRD, SEM, TEM, FT-IR, TG, UV-vis and DRS, etc. Effects of different functional monomers and different ratio on imprinted photocatalyst were investigated. From the results, when the molecular imprinted photocatalyst with the proportion of molecular template and functional monomer was1:2:6and the AM as the functional monomers, the degradation ratio of Ciprofloxacin under visible light reached70.9%. From the photodegradation experiments with different targets, we can find that the photocatalyst prepared by molecular imprinting technique has better selectivity.(3) The Cl doped TiO2imprinted photocatalyst was prepared via surface molecular imprinted technology with a facile microwave-assisted method with Tetracycline (TC) as the molecular template.4-vinyl pyridine (4-VP), Trimethylolpropaneacrylate (TMPTA), and2,2-azobisisobutyronitrile (AIBN) were considered to functional monomer, cross-linking agent and initiate, respectively. The molecular imprinted photocatalyst was characterized by XRD, SEM, TEM, FT-IR, UV-vis, DRS etc. Photocatalytic activity of the surface imprinted photocatalyst with different ratios and different solvents, reaction time, the kind of template molecule and functional monomer is discussed. From the results, we can see that When the template molecule: functional monomer:crosslinking is1:4:6, power of microwave heating is600W, the heating time is90min, the surface imprinted photocatalyst on degradation of TC solution with15mg/L reached to72.35%. At the same time, the mechanism of photocatalytic degradation with surface molecular imprinting Cl doped TiO2photocatalyst were studied. |
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