Research On Polyaniline Based Photocatalytic Materials

In recent years,the treatment of organic pollutants in the environment has become one of the hot topics in the field of environmental chemistry.As a kind of advanced oxidation technology,photocatalysis has been recognized as one of the most promising green environmental technologies.The photocatalytic degradation technology has the characteristics of no toxicity,no secondary pollution,and the applicability of the spectrum,so it has great potential application in water pollution,air pollution and soil pollution.In the environmental treatment,photocatalytic materials such as TiO₂,ZnO,SnO₂ and SnS,but in front of three kinds of photocatalytic materials have narrow spectral response range,low quantum efficiency,as photocatalytic materials dealing with toxic pollutants in wastewater has been limited.Polyaniline is a kind of conductive polymer material.Its main chain contains alternating benzene ring and nitrogen atom.Due to the advantages of cheap raw materials,simple synthesis,reversible doping,high temperature resistance and good oxidation resistance,polyaniline has attracted much attention of researchers.The full text is divided into three parts,from the detailed elaboration of the three chapters:1?In Chapter 1,the PANI/SnO₂ photocatalytic materials with different ratios were prepared by in situ composite method on spherical SnO₂.The PANI/SnO₂ composite photocatalyst was characterized by XRD,SEM,TEM,FTIR and the photocatalytic activity of methyl orange?MO?.Photocatalytic experiments show that PANI can significantly improve the photocatalytic activity of SnO₂ microspheres,and the photocatalytic degradation of methyl orange?MO?accords with the pseudo first order kinetics.1%PANI/SnO₂ can achieve the separation of electron hole pairs,the photocatalytic activity is the highest,and the pseudo first order kinetic rate constant k is more than three times of spherical SnO₂.The results of photoluminescence?PL?test show that PANI can effectively inhibit the recombination of photogenerated electron hole pairs,thus improving the photocatalytic performance.2?In Chapter 2,we synthesized the PANI/SnS photocatalytic materials by a chemical adsorption method,and decomposition of 30 mg/L MO and Rh B as typical organic pollutant models.The results shows that PANI/SnS and SnS could degrade approximately 99.5%and 47.8%of Rh B respectively,PANI/SnS is about 2 times that of pristine SnS.Meanwhile,PANI/SnS and SnS could degrade approximately 98.7%and 63.5%of MO respectively,PANI/SnS is about 1.5 times that of pristine SnS.The above results suggest that PANI has an obvious impact on photocatalytic activity improvement of SnS.Therefore,we analyze the reasons:PANI can improve the light absorption effciency of SnS;PANI can provide a "channel"for the separation of electron-hole pairs of SnS,and guide carriers.Thus,PANI/SnS materials can improve the photocatalytic degradation performance of SnS after adding PANI.3?In chapter 3,PANI/ZnO photocatalytic materials were prepared by Pickling emulsion method.The photocatalytic activity was investigated with 20 mg/L methyl orange as the substrate.The results show that both ZnO and PANI/ZnO exhibit good photocatalytic performance,and the photocatalytic effect of spherical ZnO is better than that of bar-shaped ZnO.The photocatalytic performance of HCl-doped PANI/ZnO is better than that of HAc-doped PANI/ZnO.At the initial stage of the reaction,the degradation rate of ZnO was higher than that of PANI/ZnO,but the degradation rate of PANI/ZnO was larger than that of ZnO with the increase of time.It can be seen that the doping of PANI improves the catalytic activity of ZnO.Analysis of the reasons may be wrapped in the surface of ZnO PANI absorption of photons,resulting in photogenerated electrons,photogenerated electrons transferred to the surface of ZnO redox reaction.The photocatalytic activity of ZnO photocatalyst is the combination of photogenerated electron hole and ZnO/PANI,which improves the separation rate and the existence time of photo-generated electron-hole pairs,resulting in more O₂·-,HO₂·,OH· and other oxidants,improve the efficiency of degradation of MO.