Ureolytic bacteria mediated synthesis of hairy ZnO nanostructure as photocatalyst for decolorization of dyes

In this present study, ureolytic bacteria mediated synthesis of hairy shaped ZnO nanostructure was synthesized as a photocatalyst for degradation of dye viz Methylene blue (MB), Methyl orange (MO), Rhodamine-B (Rho-B) and fresh textile effluents. Various analytical techniques were used for characterization of photocatalyst material by measuring the band gap, crystal phase and particle morphology. XRD confirmed the conversion of zinc carbonate hydroxide into hexagonal ZnO crystal phase. Results from morphological and BET studies revealed that the resultant product was ZnO hairy structures of 10-15 nm width, agglomerated to form a spherical framework with a diameter of 1.2-1.3 mu m and a specific surface area of 30.226 m(2)/g. EPR confirmed (OH)-O-center dot radical generation from the particle surface under sunlight. The photocatalytic study revealed that the hairy ZnO nanostructures enhanced the dye adsorption and stimulated/aided photo-assisted decolorization of dyes in the following order: MB (15 min) > MO (30 min) > Rho-B (35 min) > raw textile dye (45 min). The photocatalytic experimental setup was made to explore the significant photoactivity at the top surface under the sunlight. The decolorization process was rapid at the top which came down and lifted the lower portion of dye component to the top (diffusion process) for decolorization. This study explains that the hairy shaped ZnO nanostructure exhibits a good photocatalytic activity of textile dye under sunlight, which correlated with light intensity.