Preparation Of Several Nano-composites Photocatalyst And Their Photocatalytic Properties

With the rapid development of our country's economy,0.9 million tons of various dyes are produced every year,leading to serious environmental pollution.It is important to develop new technology of photocatalytic degradation of dyes in wastewater.In recent years,nano-photocatalysts have been widly applied due to improved photocatalytic performance,because they have much bigger surface area than ordinary materials and more catalytic active center.We synthesize Si,N co-doped nano-sized TiO2 through high-energy mechanical milling of TiO2 and SiO2 powders,followed by calcination at 600 ? in ammonia atmosphere.The obtained TiO2 exhibits high photocatalytic activity.On the other hand,nano-material is much easier to aggolomerate and it is difficult to recycle them in practice.To solve this problem,nano-photocatalysts are immobilized to internal or surface of porous materials,leading to better adsorptive properties and catalytic performance.We successfully prepared a series of sepiolite nanocomposite photocatalysts by a variety of cost-effective and environmentally friendly methods.The obtained nanocomposite photocatalysts exhibit high efficient in catalytic degradation of some dyes.Main results are shown following:1.Si-N codoped nano-TiO2 was achieved through high energy ball milling and thermal treated under ammonia atmosphere.The anatase Ti02 and nano-Si02 were selected as titanium and silicon source,repectively.The results showed that rutile TiO2 still have no photocatalytic activity even with Si,N co-doped,and the Si-N co-doped anatase TiO2 exhibited a high thermal stability and high photocatalytic activity when Si content is 2%.The novel and simple experimental process exhibited excellent reproducibility,which is suitable for the large-scale industrial production.2.The sepiolite/Cu2O/Cu nano composites were synthesized by one-step hydro-thermal method,and the products have been characterized.The experimental results showed that 54.3%of the Congo red was degraded by Cu2O/Cu photocatalyst,and 95.1%of the Congo red was degraded by sepiolite/Cu2O/Cu.It is not difficult to find that the catalytic efficiency of the sepiolite/Cu2O/Cu is better than that of Cu2O/Cu.3.The sepiolite/CuS nanocomposite was successfully prepared by solvothermal method.Sepiolite,nitric acid copper and thiourea were used as raw material.Its photocatalytic activity was studied through the degradation of methylene blue in Xenon lamp light.The result showed that the sepiolite/CuS nano-composite has excellent photocatalytic activity,and the 97.35%of methylene blue was degraded.4.The sepiolite/Bi2O3 nanocomposite was successfully prepared in the ethylene glycol solvent through the microwave-assisted reflux method,in whichsepiolite and bismuth nitrate were used as raw material.Its photocatalytic performance was studied.The experimental results showed that the 95.7%.of the Congo red was degraded by sepiolite/Bi2O3 photocatalyst.5.The sepiolite/Bi2S3 nanocomposite was successfully prepared,in which sepiolite,bismuth nitrate and thiourea were used as raw material.The photocatalytic mechanism of the sepiolite/Bi2S3 nanocomposite discussed preliminarily.Its photocatalytic activity was inspected through the degradation of rhodamine B in Xenon lamp light.The results showed that sepiolite/Bi2S3 nanocomposite had higher photocatalytic activity,and the 91.6%of rhodamine B was degraded by sepiolite/BihS3 photocatalyst.By comparison with their experimental results,it was found that the photocatalytic preformance of the sepiolite/Bi2S3 was much better than that of Si,N co-doped anatase TiO2 in the degradation of rhodamine B,namely metal sulfide was better than metallic oxide.The sepiolite/Bi2O3 nanocomposite was better than sepiolite/Cu2O/Cu in the degradation of r congo red.According to the results,it is found that the synergistic effect was caused between sepiolite with strong adsorption and nanostructured Cu2O/Cu,CuS,Bi2O3 and Bi2S3 in the photocatalytic degradation,and their photocatalytic performance were greatly improved in the degradation of dyes.In comparison to the acid modified sepiolite,sepiolite/nanocomposite has excellent photocatalytic performance in the degradation of relevant dye.In this paper,the problems of the reunion and recycle of the nanoscale Cu2O/Cu,CuS,Bi2O3 and Bi2S3 photocatalyst were successfully solved.These nanocomposites will be very good photocatalysts in treating dye wastewater.