Synthesis And Perfomance Study Of Fe₃O₄-SnO₂ Composites

As a new-type and environmental photocatalyst, nano-SnO₂ has been the focus of oversea and domestic researchers because of its chemical stability, good visible light transmission, anti-acid-base ability. As a n-type semiconductor with a wide band gap（Eg = 3.6e V）, SnO₂ can only absorb ultraviolet light and has very low utilization to visible light. Thus, researchers use some ways to improve its photocatalytic performance, such as semiconductor composition, metal-doping,photosensitization. As a kind of multifunctional magnetic material, nano-Fe₃O₄ has many excellent properties and is used widely in catalysis, magnetic recording, medicine,separation and detection and other fields. If we can combine Fe₃O₄ and SnO₂ together to synthesis Fe₃O₄-SnO₂ composites, it will improve the photo-Fenton catalytic activity of SnO₂ by utilizing the synergy of Fe₃O₄ and SnO₂ and we can also make use of the magnetic of Fe₃O₄ to solve the problem of materials recycling.In this paper, we used solvothermal method to synthesis Fe₃O₄/SnO₂ composites,Fe₃O₄ nanoparticles and Fe₃O₄@SnO₂ core-Shell composites that adopted Fe₃O₄ as carriers and researched their photo-Fenton catalytic performance. On account of the relatively high surface area of Fe₃O₄/SnO₂, we also studied its adsorption property.Specific research contents and conclusions are as follows:（1） We used solvothermal method to prepare Fe₃O₄/SnO₂ of different compound proportion by changing the ratio of reactants and studied the impact of p H value, H2O2 dosge, catalyst loading, etc to the performance of photo-Fenton catalytic degradation of methylene blue. The results showed that the photo-Fenton catalytic performance reached the highest value as selecting 10 mg 1:3 Fe₃O₄/SnO₂,adding 1m L H2O2, adjusting p H to 3 and the adsorption property attained the best as selecting 30 mg 1:6 Fe₃O₄/SnO₂, adjusting p H to 10.（2） We used solvothermal method to synthesis Fe₃O₄@SnO₂ core-Shell composites and studied the impact of the ratio of reactants, temperature, the source of Sn, and so on to the products. It turned out that the phenomenon of SnO₂ coated on the surface of Fe₃O₄ was the most obvious, when we chose PVP as the surfactant, 200℃ as the reaction temperature, Sn Cl4·5H2O as the source of Sn. Furthermore, we adopted a novel method to synthesis SnO₂ nanoparticles whose particle size was about 14 nm, in thispaper. To do blank experiments, we tested the catalytic performance of Fe₃O₄, SnO₂ and Fe₃O₄@SnO₂. The results showed that the catalytic performance of Fe₃O₄@SnO₂ was better than SnO₂ and Fe₃O₄ and the catalytic performance of 1:2 Fe₃O₄@SnO₂ was best.