Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
8 results
Search Results
Item Visible light-induced photocatalytic degradation of Reactive Blue-19 over highly efficient polyaniline-TiO2 nanocomposite: a comparative study with solar and UV photocatalysis(Springer Verlag service@springer.de, 2018) Kalikeri, S.; Kamath, N.; Gadgil, D.J.; Shetty K, V.Polyaniline-TiO2 (PANI-TiO2) nanocomposite was prepared by in situ polymerisation method. X-ray diffractogram (XRD) showed the formation of PANI-TiO2 nanocomposite with the average crystallite size of 46 nm containing anatase TiO2. The PANI-TiO2 nanocomposite consisted of short-chained fibrous structure of PANI with spherical TiO2 nanoparticles dispersed at the tips and edge of the fibres. The average hydrodynamic diameter of the nanocomposite was 99.5 nm. The band gap energy was 2.1 eV which showed its ability to absorb light in the visible range. The nanocomposite exhibited better visible light-mediated photocatalytic activity than TiO2 (Degussa P25) in terms of degradation of Reactive Blue (RB-19) dye. The photocatalysis was favoured under initial acidic pH, and complete degradation of 50 mg/L dye could be achieved at optimum catalyst loading of 1 g/L. The kinetics of degradation followed the Langmuir-Hinshelhood model. PANI-TiO2 nanocomposite showed almost similar photocatalytic activity under UV and visible light as well as in the solar light which comprises of radiation in both UV and visible light range. Chemical oxygen demand removal of 86% could also be achieved under visible light, confirming that simultaneous mineralization of the dye occurred during photocatalysis. PANI-TiO2 nanocomposites are promising photocatalysts for the treatment of industrial wastewater containing RB-19 dye. © 2017, Springer-Verlag GmbH Germany, part of Springer Nature.Item Solar light-driven photocatalysis using mixed-phase bismuth ferrite (BiFeO3/Bi25FeO40) nanoparticles for remediation of dye-contaminated water: kinetics and comparison with artificial UV and visible light-mediated photocatalysis(Springer Verlag service@springer.de, 2018) Kalikeri, S.; Shetty K, V.Mixed-phase bismuth ferrite (BFO) nanoparticles were prepared by co-precipitation method using potassium hydroxide as the precipitant. X-ray diffractogram (XRD) of the particles showed the formation of mixed-phase BFO nanoparticles containing BiFeO3/Bi25FeO40 phases with the crystallite size of 70 nm. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed the formation of quasi-spherical particles. The BFO nanoparticles were uniform sized with narrow size range and with the average hydrodynamic diameter of 76 nm. The band gap energy of 2.2 eV showed its ability to absorb light even in the visible range. Water contaminated with Acid Yellow (AY-17) and Reactive Blue (RB-19) dye was treated by photocatalysis under UV, visible, and solar light irradiation using the BFO nanoparticles. The BFO nanoparticles showed maximum photocatalytical activity under solar light as compared to UV and visible irradiations, and photocatalysis was favored under acidic pH. Complete degradation of AY-17 dyes and around 95% degradation of RB-19 could be achieved under solar light at pH 5. The kinetics of degradation followed the Langmuir–Hinshelhood kinetic model showing that the heterogeneous photocatalysis is adsorption controlled. The findings of this work prove the synthesized BFO nanoparticles as promising photocatalysts for the treatment of dye-contaminated industrial wastewater. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.Item Floating bed reactor for visible light induced photocatalytic degradation of Acid Yellow 17 using polyaniline-TiO2 nanocomposites immobilized on polystyrene cubes(Springer, 2020) Nair, V.R.; Shetty K, V.In the present study, PANI-TiO2 nanocomposites have been used in suspended and immobilized form for photocatalytic degradation of Acid Yellow 17 (AY-17) dye under visible light. PANI-TiO2 nanocomposites were immobilized in polystyrene cubes to form PANI-TiO2 @ polystyrene cubes. The nanocomposites were found to be visible light active both in suspended and immobilized form. PANI-TiO2 nanocomposite with 13% TiO2 loading was found to be the optimum in terms of maximum degradation of AY-17. The efficiency of floating bed photoreactor (FBR) operated in liquid recycle mode using PANI-TiO2 @ polystyrene cubes was studied. In this reactor, around 89% degradation of 1 L of AY-17 with an initial concentration of 10 mg/L could be achieved with 2.83 g/L per pass of immobilized catalyst. The FBR operated with PANI-TiO2 @ polystyrene cubes has exhibited good performance as a photocatalytic reactor and may be recommended over other conventional photo reactors for treatment of wastewater contaminated with synthetic dyes. The kinetics of degradation of AY-17 by photocatalysis under visible light with suspended PANI-TiO2 and PANI-TiO2 @ polystyrene cubes followed first-order kinetics. The values of apparent kinetic parameter for degradation by immobilized photocatalysts are lower than the corresponding kinetic parameter for suspended photocatalysts. It confirms the existence of diffusional limitations in photocatalysis by PANI-TiO2 @polystyrene cubes. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.Item Suspended and polycaprolactone immobilized Ag @TiO2/polyaniline nanocomposites for water disinfection and endotoxin degradation by visible and solar light-mediated photocatalysis(Springer Science and Business Media Deutschland GmbH, 2021) Gadgil, D.J.; Shetty K, V.In the present study, water contaminated with Escherichia coli (E. coli) cells was photocataytically disinfected using Ag core-TiO2 shell/Polyaniline nanocomposite (Ag@TiO2/PANI) under visible light irradiation. Ag@TiO2/PANI containing 13 weight % of Ag@TiO2 was found to offer maximum disinfection activity. Band gap energy of Ag@TiO2/PANI was found to be 2.58 eV. Ag@TiO2/PANI nanocomposites were efficient in water disinfection in their suspended and immobilized form. Rate of disinfection with Ag@TiO2/PANI was faster than that with Ag@TiO2 nanoparticles. Water containing 50 × 108 CFU/mL cells was completely disinfected within 120 min with 1 g/L Ag@TiO2/PANI nanocomposite. Simultaneous disinfection and endotoxins degradation were achieved. The photocatalytic disinfection of water and endotoxin degradation using Ag@TiO2/PANI nanocomposite under visible light irradiation followed second order kinetics. The nanocomposite also exhibited a good solar photocatalytic activity. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.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 Solar light active biogenic titanium dioxide embedded silver oxide (AgO/Ag2O@TiO2) nanocomposite structures for dye degradation by photocatalysis(Elsevier Ltd, 2021) Deekshitha; Shetty K, V.A novel method of synthesis of TiO2 embedded AgO/Ag2O nanocomposite using the cell free culture supernatant of the bacteria Alcaligenes aquatilis at room temperature is reported. Highly crystalline nanocomposite containing rutile TiO2, Ag2O and AgO was formed by the biosynthesis route. AgO/Ag2O particles were embedded in TiO2 and the average particle size was found to be 13.4 nm. The synthesized nanocomposite with a band gap energy of 1.75 eV was found to degrade 100 ppm Reactive Blue 220 dye almost completely in acidic pH at a catalyst loading of 1 g/L under visible light irradiation in 90 min. The nanocomposites also showed good photocatalytic activity under solar light, and thus can be used effectively in solar driven photocatalysis for waste water treatment. © 2021 Elsevier LtdItem Visible light irradiated photocatalytic reduction of CO2 to hydrocarbons using hybrid polyaniline/ CuO nanocomposite in aqueous system(Taylor and Francis Ltd., 2022) Matthew, D.; Shetty K, V.The ever-increasing energy demand has resulted in an increase in CO2 emissions and global warming. Photocatalytic reduction of CO2 to methanol, which is considered to be the next generation alternate fuel is gaining interest to combat global warming and to move towards a methanol economy. The present work focuses on photocatalytic reduction of CO2 using Polyaniline/CuO (PANI/CuO) nanocomposite to methanol, formic acid, and formaldehyde under visible light irradiation. CuO nanoparticles were synthesised using the aqueous extract of Tectona grandis (teak) leaves and further used in the synthesis of PANI/CuO nanocomposite with different CuO loading. PANI/CuO nanocomposite exhibited visible light activity in the reduction of CO2 to form methanol, formic acid, and formaldehyde. Photocatalytic reduction of CO2 with PANI/CuO nanocomposite containing 13.7% by weight of CuO resulted in a maximum yield of methanol. The band gap energy of the nanocomposite was found to be 2.28 eV, thus confirming its good visible light activity and the PANI-CuO heterojunction-based mechanism of photocatalysis is proposed. The synthesis of PANI-CuO photocatalyst uses CuO which is synthesised by an eco-friendly route with the utilisation of teak leaves, a timber industry waste and thus it can serve as a greener catalyst. © 2022 Indian Institute of Chemical Engineers.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.