Study On Photo-catalysis Performance Of Polyaniline And Metal Oxides Composite

To improve the photocatalytic efficiency in removing HCHO from indoor air and the purification ability of organic waste water,coated composite of PANi(polyaniline)TiO₂-SiO₂ on stainless steel was studied for its HCHO adsorption capacity and synergetic photocatalytic effect.Also PANi/TiO₂ composite catalyst was studied for adsorption and uv photo-catalytic oxidation of bisphenol A in aquaeous phase.Removal of bisphenol A from water using MnO₂ (manganese dioxide) was also studied.Firstly,composite PANi/TiO₂-SiO₂ was prepared by adsorption of organic acid or hydrochloric acid doped PANi in solution,and characterized by FTIR and UV-Vis spectra,the later showed extended absorbency well into the visible wavelength range.Cyclic voltammetry curves proved that PANi was stable and the adsorption of formaldehyde on PANi resulted in the occurrence of HCHO related electrochemical peak. The effect of catalyst coating times,concentrations of PANi solution during adsorption and PANi doping acid(organic acid,hydrochloric acid) on photocatalytic degradation of formaldehyde was investigated under UV irradiation.Loading three layers TiO₂-SiO₂ and immersing in 0.26g/L HCl doped PANi/THF solution produced the best photocatalyst with the highest activity under UV,which is 3times the HCHO removal rate of a TiO₂-SiO₂ film without PANI.The PANi/TiO₂-SiO₂ doped with organic acid had faster initial HCHO oxidation rate than that doped with inorganic acid,but the final removal rate was same.The photocatalytic oxidation activity of formaldehyde under visible light was proved for PANi/TiO₂-SiO₂ in removing HCHO from air,though lower than the activity under UV.HCHO removal rate is faster at lower concentration.Secondly,different mass ratio of PANi and TiO₂ was investigated for uv photocatalytic oxidation of bisphenol A in water,and effect of different pH was investigated,also inevstigated is adsorption and photocatalysis of bisphenol A.The result show that PANi/TiO₂ composite catalyst had the best result in removing bisphenol A at pH4,mass ratio 1:50.The final removal rate can reach above 95%.Comparing with unloaded PANi,the removal rate of bisphenol A increased by 30%.Finally,effect of different dosage of MnO₂,pH and illumination,and blending with TiO₂ and doping with PANi were investigated for removal of bisphenol A,and repeated experiments were carried out.The results showed that the best removal effect of bisphenol A was achieved at 0.1g dosage and pH=4.After reaction for 15min,the removal rate can reach above 95%.Removal of BPA by MnO₂ was decreased by illumination,blending with TiO₂ and doping with PANi to some extent decreased removal of bisphenol A.After MnO₂ was used once,the removal capacity decreased and there was no obvious change after further repeated tests for several times.