Visible light mediated photocatalytic dye degradation using Ag2O/AgO-TiO2 nanocomposite synthesized by extracellular bacterial mediated synthesis - An eco-friendly approach for pollution abatement

Abstract

A large quantity of dyes released with textile industry effluents has raised a lot of concern due to their harmful and toxic effect on the ecosystem. The present study reports a novel method for the synthesis of visible light active photocatalyst by a bacterial based synthesis approach for the degradation of dyes. Ag2O/AgO-TiO2 nanocomposite particles with an average crystallite size of 38 nm, containing rutile TiO2 were synthesized using the cell free supernatant of the culture broth of Alcaligenes aquatilis. The particles were spherical, distinct with average particle size of 39.6 nm. The particles were found to be visible light active with the band gap energy value of 1.5 eV and photocatalytically active in the degradation of Reactive Blue 220 (RB 220). Around 96% of 100 ppm dye could be degraded in 90 min under visible light irradiation using the biosynthesized Ag2O/AgO-TiO2 nanocomposites. The biosynthesized nanocomposite exhibited good solar photocatalytic activity not only in the degradation of RB 220, but also in degrading the azo dyes, such as Acid Yellow 17 and Methyl Orange. The activity of biosynthesized nanocomposite was found to be better than that of Bio-TiO2. These results demonstrated an eco-friendly, potentially economical and greener method for the synthesis of Ag2O/AgO-TiO2 nanocomposites, with involvement of minimum technical challenges in terms of downstream processing and less energy consumption, with a broad scope of application in solar light mediated photocatalytic treatment of waste water.