Preparation Of Cellulose Modified ZnO, CdS And CdS / ZnO And Their Photocatalytic Application

When people enjoy and develop convenient and colorful life, the environment that human beings live on is destroyed irreversibly. Taking environment crisis into consideration, green chemical industry, the conversion and storage of clean energy and environmentally friendly sewage treatment technology have been focuses in the scientific field. Semiconductor photo catalysis is a kind of environmentally friendly green catalytic technology. It can make solar energy convert into chemical and electric energy. It is helpful to solve pollution and energy crisis. Therefore, this paper does a modification research on ZnO and CdS to get photo catalytic material whose photo catalytic performance is improved with the help of green microwave assisted synthesis technology. This dissertation focuses on the synthesis, modification and physical and chemical photo catalysis application of ZnO or CdS in order to develop new efficient ZnO and CdS. The dissertation is mainly composed of three dimensions.1. Simple and novel preparation has been adopted. Regarding cellulose as a template, ZnO crystals in micron and nano size with cellulose tubular morphology structure were got by roasting cellulose in high temperature. The higher the roasting temperature is, the degree of crystallization gets better. And the experiments indicates that the best photo catalytic effect can be obtained at 850℃:The decomposing efficiency of methylene blue reaches to 97% in 60min, which is superior than that acquired by preparations without templates at the same temperature. In the mean time, large quantities of hexagonal shaped ZnO crystal, the (001) crystal face can be observed.2. Through loading CdS to the cellulose matrix by hydrothermal method, we can get spherical CdS whose matrix is cellulose and keep nano CdS grain off the water. Observing the photo catalytic effect under visible light and UVA made by long arc mercury lamp, it is found that the particle size changes as temperature and time of reaction increases. When the reacting time comes to 12h, the particle size gets coarser as the temperature increases and cellulose starts to carbonize. The results indicates that the best photo catalytic effect can be acquired at 120℃ in 12h and the decomposing efficiency of methlene blue reaches to 95% in 50min.3. We gain a kind of ZnO/CdS in core/shell compound structure material which is carried by carbonized cotton wool through the environmental microwave assisted synthesis technology. Compared to ZnO, this kind of material improves the catalytic efficiency and widens spectral response range. In addition, it restrains the recombination of carrier, stop CdS from photo corrosion and prevents nano particle from water which can enhance the recoverability of catalyst. Detailed studies on the photo catalysis ability of this kind of material have been made. When adding 0.6g zinc acetate is added and calcination temperature roasted is at 600 ℃, the CdS/ZnO composite material achieved presents good visible-light response and the efficiency of methlene blue reaches to 91% in 50min.We design and improve the photo catalyst from both physical and chemical levels through the systematic study on the preparation and catalytic ability of ZnO/CdS composite material discussed above. Catalyst with better catalytic activity and recoverability has been obtained, and the results can provide fresh perspective for developing new type of efficient semiconductor catalysts.