Faculty Publications
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Item Visible light mediated photocatalytic dye degradation using Ag2O/AgO-TiO2nanocomposite synthesized by extracellular bacterial mediated synthesis - An eco-friendly approach for pollution abatement(Elsevier Ltd, 2021) Kulal, D.; Shetty K, V.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. © 2021 Elsevier Ltd.Item Extracellular biosynthesis of CuO-TiO2 nanocomposites using Alcaligenes aquatilis for the photodegradation of reactive and azo dyes under visible light irradiation(Springer, 2025) Agarwalla, S.; Shetty K, V.In this study, CuO/TiO2 nanocomposites were biologically synthesized using cell-free supernatant (CFS) of Alcaligenes aquatilis growth culture by two-step synthesis method, one-pot method with sequential addition of precursors, and one-pot method with simultaneous addition of precursors. The one-pot method with simultaneous addition of precursors was found to be the best method for the synthesis in terms of degradation of reactive blue-220 (RB-220) and acid yellow-17 (AY-17) dyes under visible light irradiation. CuO/TiO2 nanocomposite was found to have the crystallite size of 14.7nm and the bandgap energy of 2.5 eV. The effect of synthesis parameters such as synthesis time, pH of CFS, and the ratio of Cu to Ti in the synthesis mixture on the photocatalytic degradation efficacy of these nanocomposite structures under visible light irradiation was studied. The optimum conditions for the synthesis of CuO/TiO2 nanocomposite particles by one-pot method with simultaneous addition of precursors were found to be pH 12 of CFS, synthesis duration of 24 h, and molar ratio of Cu to Ti in the synthesis mixture as 1:22 for RB-220 dye and 1:25 for AY-17 degradation. CuO/TiO2 nanocomposite particles synthesized under the optimum conditions and without any calcination could degrade RB-220 and AY-17 dyes completely in 120 min and 150 min, respectively. The kinetics of degradation of RB-220 and AY-17 by CuO@TiO2 nanocomposite particles followed first-order kinetic model with rate constant of 0.028 min?1 and 0.018 min?1, respectively. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2023.