Synthesis Of Bi₂S₃/AgBiS₂ Nanocomposites And Its Application In The Treatment Of Organic Dyes

With the development of human society, the problem of environmental pollution is more and more serious, especially the water pollution, which has significant threatened human life and health. Photocatalytic degradation and adsorption can effectively remove the organic pollutants in the water, which is the main means to deal with the organic pollutants. Because traditional photocatalytic materials?such as TiO₂, ZnO, SnO₂, etc? are wide band gap semiconductor material with lower utilization of sunlight, researchers have been working to explore new narrow band gap semiconductor photocatalytic materials, or to modify the existing semiconductor photocatalyst by doping or composition, in order to improve the photocatalytic performance; conventional adsorption materials such as silica gel, activated alumina, activated carbon and zeolite with stable structure have good adsorption performance, but their production cost is high. So it has important significance to study the photocatalytic degradation and adsorption, and it is still the focus of scientific researchers to use simple and cheap methods to prepare high efficient photocatalyst and adsorbent.Bismuth compounds play a very important role in the field of photocatalysis, photovoltaic and thermoelectric, because of their low toxicity and stability, as well as the unique layered structure. In this paper, a simple solvothermal method is used to synthesize nanoscale Bi₂S₃, AgBiS₂ and Bi₂S₃/AgBiS₂ composites, and their application in the field of organic dye treatment is also studied. The main research contents are as follows:1. Uniform flower like Bi₂S₃ nanomaterials are prepared by solvothermal method, and the influence of different reaction conditions?raw material, solvent, raw material ratio, reaction temperature? on the morphology of Bi₂S₃ is studied. In our experiment, CH₃COONH₄ is used to control the morphology of the product, which plays an important role in the nucleation and growth of the Bi₂S₃ nanoflower. The ultraviolet-visible diffuse reflectance spectrum?UV-vis DRS? shows that Bi₂S₃ nanomaterials have strong absorption in the visible light region, and blue shift occurrs compared to powder materials, which may be caused of quantum confinement effect of nanoparticles. The visible light photocatalytic activity of the synthesized Bi₂S₃ nanomaterials is evaluated by the degradation of RB and MO, and the degradation effect of RB is superior to that of MO.2. Uniform cluster like AgBiS₂ nanomaterials are prepared in the assisted of CH₃COONH₄ by solvothermal method, and the influence of reaction conditions on the morphology of AgBiS₂ is studied. The UV-vis DRS shows that AgBiS₂ nanomaterials have strong absorption in the visible light region, and blue shift occurrs compared to powder materials, which may be caused of quantum confinement effect of nanoparticles. There are almost no relevant reports about the photocatalytic properties of AgBiS₂ nanomaterials, in our experiment, the visible light photocatalytic activity of the synthesized AgBiS₂ nanomaterials is evaluated by the degradation of RB and MO, and the degradation effect of RB is superior to that of MO. Its photocatalytic performance is significantly better than that of Bi₂S₃ nano materials.3 There is a few reports about Bi₂S₃/AgBiS₂ composites at present, which are synthesied by a simple solvothermal method, in the assisted of CH₃COONH₄, and pure AgBiS₂ or Bi₂S₃/AgBiS₂ nanocomposites can be prepared through control additive sequence respectively. This method may provide a new way of thinking for the synthesis of such composite materials. The photocatalytic performance and adsorption performance of the Bi₂S₃/AgBiS₂ nanocomposites are also studied, and the latter is far better than the former. The removal rate of the Bi₂S₃/AgBiS₂ nanocomposites can be reached about 97% under adsorption for 5 min, but the adsorption performance of single Bi₂S₃ and AgBiS₂ is worse than that of the Bi₂S₃/AgBiS₂ nanocomposites. The effects of pH value, initial concentration, and the temperature on adsorption rate of MO are investigated. Results show that the adsorption performance is the best in the neutral condition; when the initial concentration of MO is lower than 50 mg/L, removal rate is up to 98%, adsorption capacity reaches saturation when the concentration is 50 mg/L, but the removal rate decreases with increasing of concentration; temperature has little effect on the adsorption properties, we think that the adsorption process are chemical adsorption.