Preparation Of Nanometer ZnO/Polymer Composites And Study On Their Photocatalytic Property

In the recent years, being the most environment-friendly pollution-treatment method, semiconductor photocatalysis technology used for water treatment has attracted more attention because it has many advantages such as simple preparation technology, economical advantages, no secondary pollution, and so on. Nanometer ZnO is an important semiconductor material whose bandgap is similar to that of TiO₂. However, the photocatalytic process can only be conducted under UV irradiation because nanometer ZnO has wide bandgap and the energy needed by electrons transiting from valence band to conduction band is strong, then the practical application of photocatalysis technology is limited. Therefore, it is necessary and profound to develop photocatalysts with high photocatalytic property under visible light irradiation. In this paper, composites with high photocatalytic property under visible light irradiation were prepared through complexing polymer and nanometer ZnO. The details are as follows.1. Preparation of composite based on nanometer ZnO/PS and study on its photocatalytic propertyIn this experiment, composite precursor was prepared by mixing polystyrene and nanometer ZnO precursor, and its decomposition temperature and relative thermal decomposition data were determined by the analysis of TG-DTA. The target composite was obtained by calcining the precursor at appropriate temperature according to the results of TG-DTA analysis. TEM,XRD,FT- IR,UV-Vis,ESR were used to characterize the composite. Under the irradiation of fluorescence lamp, the photocatalytic property of this composite was tested and compared with that of pure nanometer ZnO. The results indicated that after irradiating 11 hours the decolorization proportion of methyl orange was 35 % by using composite, which was much larger than 5 % by using pure nanometer ZnO.2. Preparation of composite based on nanometer ZnO/PVC and study on its photocatalytic propertyComposite precursor was synthesized by mixing nanometer ZnO and polyvinyl chloride solution, decomposition temperature and relative thermal decomposition data were obtained by TG-DTA analysis. The target composite was prepared by calcining the precursor at appropriate temperature according to the results of TG-DTA analysis. TEM, FT-IR, UV-Vis, ESR were used to analyze the composite. Under the irradiation of fluorescence lamp, the photocatalytic property of composite was tested. Also, theeffects of proportion of raw materials, calcining temperature and calcining time on photocatalytic property of composite were studied. The results indicated that when the quality proportion of ZnO and PVC was 1/1, the calcining temperature was 250℃ and the calcining time was 1hour, the photocatalytic property of composite was the best.3. Photocatalytic degradation of methyl orange with composite based on nanometer ZnO/PVCIn this experiment, the effects of MO initial concentration, catalyst amount and pH value of solution on the photocatalytic property of the composite were investigated. The results indicated that the photodegradation rate of MO solution decreased with the increasing photocatalytic time and MO initial concentration and increased with the increasing photocatalyst amount. While, when the amount of photocatalyst increased to some value, the photodegradation rate of MO solution increased slowly. Besides, neutral solution condition was favorable to the degradation of MO solution.4. Photocatalytic degradation of aniline with composite based on nanometer ZnO/PVCIn this experiment, the effect of aniline initial concentration, catalyst amount and initial pH value of solution on the photocatalytic property of composite were investigated. The results indicated that the photodegradation rate of aniline solution decreased with the increasing photocatalytic time and aniline initial concentration and increased with the increasing photocatalyst amount. While, when the amount of photocatalyst increased to some value, the photodegradation rate of aniline solution increased slowly. Besides, acidic condition was favorable to the degradation of aniline solution.