Research On Facile Preparation Of Visible Light Catalysts On The Bis Of Zn_0.25Cd_0.75S And The Degradation Performance Of Organic Pollutants In Water

With the rapid development of chemical industries including pesticide, dyestuff and petroleum energy, the problem of energy crisis and environmental pollution is increasingly serious. Water pollution, which is closely related with human life, is particularly serious. The traditional water treatment technology has many defects including slow degradation, low removal efficiency, hard recovery and secondary pollution. Therefore, it is important to seek a late-model efficient water treatment technology to overcome these shortcomings. Semiconductor photocatalytic technology, which can degrade organic pollutants in wastewater efficiently and completely under a mild condition, has a good application prospect. As classic photocatalyst, TiO2 has a low quantum yield, poor solar energy utilization and deactivation easily, which greatly limits its practical application. For these reasons, developing and preparing the visible light catalysts with high activity, strong stability and wide spectral range has become the focus and hot spot of photocatalysis research.In this dissertation, PI/Zn0.25Cd0.75 S, Melem/Zn0.25Cd0.75 S, Zn0.25Cd0.75S/Zn2GeO4 these three new efficient visible light photocatalysts are prepared by solid polymerization and hydro-thermal method, or two-step hydro-thermal method respectively. The evaluating indicator of the photocatalytic performance is the removal rate of organic pollutants in liquid phase simulations in dye wastewater. Scanning electron microscopy(SEM), transmission electron microscopy(TEM), X ray powder diffraction(XRD), Fourier transform infrared spectrum(FTIR)and X-ray photoelectron spectroscopy(XPS) are employed to character the bulk phase, morphology, the chemical state of element and functional molecular structure of these three photocatalysts. The optical properties of the catalyst, photo catalytic degradation rate of pollutants and the energy band structure are investigated by ultraviolet-visible diffuse reflection spectrum(UV-Vis DRS), ultraviolet visible spectrophotometer of TU-190, photocurrent, electrochemical impedance spectroscopy(EIS) and Mort Schottky curve.The main results and conclusions obtained from these studies are as follows:(1)ZnxCd1-xS solution is prepared using the method of similar semiconductor miscibility with ZnS and CdS in a certain proportion under the condition of Zn/Cd=1:3, Na2S·9H2O as the sulfur source. Zn0.25Cd0.75 S nanoparticle with particle size of 15 nm has been synthesized, which has good optical activity.(2)PI/Zn0.25Cd0.75 S can be synthesized based on the Zn0.25Cd0.75 S nanoparticle. Under visible light irradiation, the composite material with 30 % weight ratio of PI shows the highest photocatalytic activity, the removal rate of MO、RhB can reach more than 99% in 30 minutes.(3)Melem as a conjugated polymer is similar with PI and the preparation method is simple. The photocatalytic performance of Melem/Zn0.25Cd0.75 S is performed towards the degradation of MO and BPA. Its photocatalytic activity is higher than PI/Zn0.25Cd0.75 S, the removal rate can reach 98.7% in 25 minutes. The removal rate of BPA reaches 67%.(4)In the removal of MB photocatalytic activity test, the removal rate of Zn0.25Cd0.75S/Zn2GeO4 nanoparticle can reach 99.5%.The innovations of this work are as follows:(1) PI/Zn0.25Cd0.75 S, Melem/Zn0.25Cd0.75 S realized the effective compound organic material and inorganic material for the first time. The method does not need to add any other solvent, surfactant active agent and template. It provides a new idea for the designing and developing the visible light photocatalyst.(2)The common solution polymerization is replaced by solid polymerization in the process of preparing. It’s a simple green, environmentally friendly method of synthesis with nontoxic organic solvents effectually used.