Synthesis of adsorption cum photocatalytic nature of polyaniline-ZnO/chitosan composite for removal of textile dyes

The polyaniline-ZnO/chitosan (PZO/chitosan) nanocomposite synthesized using aniline, ZnCl2 and chitosan through precipitation-oxidation method and the synthesized composite was extensively characterized by Fourier transform infrared spectra, UV-vis spectroscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffraction measurements which indicated that the successful formation of ZO nano-rod present inside the chitosan-polyaniline composite. The adsorption and photocatalytic properties of the prepared samples were evaluated by measuring the decrease in concentration of reactive orange after adsorption in the dark and photocatalytic reaction under UV irradiation, respectively. The influences of initial dye concentration, catalyst amount and pH of the reaction solution on reactive orange decolorization were investigated. It was found that the rate of composite/dye interaction was enhanced with the increased load of composite and retarded with the increase in initial dye concentration and pH. Compared with reactive orange, methylene blue as a target pollutant, the adsorption-photocatalytic activities of the resulting composites under different light sources (dark, sunshade, UV and direct sunlight) were also investigated. Results indicates that the maximum color removal were 96% and 88.5% for reactive orange and methylene blue with the corresponding dye concentration 50mg L-1, PZO/chitosan amount of 0.3g L-1 and neutral pH in 120min of sunlight exposure respectively. Based on the results, we conclude that PZO/chitosan nanocomposite having both the advantages of photodegradation-adsorption process in the abatement of various wastewater pollutants.