Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
10 results
Search Results
Item Visible light assisted photocatalytic reduction of chromium (VI) using PANI/TiO2nanocomposite from aqueous solutions(American Institute of Physics Inc., 2023) Rathna, T.; JagadeeshBabu, J.P.Polyaniline (PANI)/TiO2 composite was prepared by in-situ chemical polymerisation of aniline monomer in the presence of ammonium persulfate (APS) and Degussa P25. The setbacks of TiO2 semiconductor catalysts like low visible light exploitation and aggregation of TiO2 nanoparticles can be avoided by incorporating PANI. The electron acceptability, electrically tuneable properties, optical and photoelectrical properties, chemical and thermal stability makes the conducting PANI a key for property enhancement of catalysts. The characterisation of nanocomposite was done using Attenuated total reflectance - Fourier transform infrared spectroscopy (ATR-FTIR), Brunauer-Emmett-Teller (BET), Transmission electron spectroscopy (TEM) and Thermal gravimetric (TGA) analysis. This synergic effect of PANI-TiO2 was exploited for the removal of Cr(VI) from the wastewater in this work. PANI is rich in positively charged amino groups that can potentially adsorb Cr(VI) anions and convert to less toxic Cr(III) on the catalyst's surface. Suspended PANI/TiO2 reveals the excellent conversion (99.90%) of Cr(VI) in acidic pH under visible light irradiation. The emeraldine salt form of PANI is more reactive to Cr(VI) and the conversion to emeraldine base form is the endpoint of the reduction reaction. © 2023 Author(s).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 Fabrication of visible-light assisted TiO2-WO3-PANI membrane for effective reduction of chromium (VI) in photocatalytic membrane reactor(Elsevier B.V., 2021) Rathna, T.; JagadeeshBabu, J.; RubenSudhakar, D.In this work, TiO 2-WO3(40:1) nanoparticles were hydrothermally prepared and, embedded in Polyaniline (PANI) membrane with varying concentrations (3–7 wt%) and, used in photocatalytic membrane reactor for the removal of Cr(VI) from the aqueous solutions. 4-methyl piperidine (4-MP) was used as a gel inhibiting agent in N-methyl-2-pyrrolidone (NMP) solvent to prepare PANI-based flat-sheet membranes by phase inversion method. Through different characterization technique, it has been found that TiO 2-WO3 incorporated PANI membranes showed enhanced membrane properties like better hydrophilicity, better antifouling properties, higher water uptake, lower contact angle, higher porosity, and better heavy metal removal efficiency compared to bare PANI membranes. PANI membrane with 5 wt% TiO 2-WO3 exhibited a percentage rejection of 98.50% within 60 min at 0.5 MPa transmembrane pressure. Cr(VI) reduction under light and dark conditions was performed in a dead-end filtration cell with a quartz window at the top and the 5 wt% TiO 2-WO3– PANI membrane showed 67.32% reduction under visible light. TiO 2-WO3 incorporated PANI nanofiltration membranes can act as an integrated system consists of a short-circuited photo-anode and cathode under visible light irradiation. Overall, TiO 2-PANI membranes promote Cr(VI) reduction to Cr(III) in the photocatalytic membrane reactor and exhibits a better self-cleaning property. © 2021Item 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 TiO2-WO3 nanocube-polyaniline hierarchical membrane for efficient removal of chromium in a photocatalytic membrane reactor(John Wiley and Sons Inc, 2023) Rathna, T.; JagadeeshBabu, J.; Ruben Sudhakar, D.R.In this article, the rational design of a physically coated TiO2-WO3 nanocube-polyaniline photocatalytic membrane (hierarchical) reactor for the efficient reduction of chromium (VI) under visible light is discussed. The incorporation of TiO2-WO3 in the polyaniline (PANI) membrane provides excellent hydrophilicity and high photo-corrosion resistance and facilitates the rapid permeation of water with a flux rate of 12 L/m2 h and higher Cr (VI) reduction. The exposure of bare PANI membranes in Cr (VI) solution leads to over-oxidation of PANI membrane and eventually leads to the destruction of the membrane. The hierarchical photocatalytic coating improves the lifetime of the membrane by blocking it from deprotonation. The photocatalytic membrane could offer 79.30% Cr (VI) reduction under visible light irradiation in a photocatalytic membrane reactor. After several reduction cycles, the membrane showed good self-cleaning ability. The present work suggests that TiO2-WO3 nanocube-coated PANI hierarchical membrane is a promising approach for the reduction and removal of Cr (VI) from wastewater. © 2023 CIWEM.Item Cobalt-doped LaFeO3 for photo-Fenton degradation of organic pollutants and visible-light-assisted water splitting(Springer, 2024) James, A.; Rodney, J.D.; Manojbabu, A.; Joshi, S.; Rao, L.; Badekai Ramachandra, B.R.; Udayashankar, N.K.The increasing demand for clean energy sources and the growing concerns about environmental pollution have led to a significant interest in developing efficient photocatalytic and photoelectrochemical systems. Here, we report the visible-light-induced photo-Fenton catalytic degradation of Methylene Blue (MB) dye over LaFeO3 and LaCo xFe1−xO3 (x = 0.01, 0.05, 0.1) catalysts synthesized via the facile combustion method. The LaCo0.01Fe0.99O3 has significantly enhanced the photo-Fenton catalytic efficiency of LaFeO3 from 67.75 to 93.85% for MB dye removal after 180 min of light irradiation. The rate constants calculated via the pseudo-first-order kinetics mechanism are found to be 0.00532/min for LaFeO3 and 0.01476/min for LaCo0.01Fe0.99O3, respectively. In addition, the most effective LaCo0.01Fe0.99O3 catalyst has demonstrated remarkable degradation performance towards Tetracycline (TC) and Methyl Orange (MO) dye with an efficacy of 93.81% and 69.67%, respectively, indicating its versatility. Further, the pristine and doped LaFeO3 were structurally optimized using DFT, and the computed band gaps were following the experimental data. Interestingly, the same catalyst can be employed as a light-induced electrocatalyst in addition to water treatment by taking advantage of its dual functionality. The LaCo0.01Fe0.99O3 catalyst achieved a benchmark current density of 10 mA/cm2 for H2 evolution at an overpotential of 297 mV vs. RHE which further improved to 190 mV vs. RHE under illumination. This work provides valuable insights on partial Co incorporation at the B-site of LaFeO3 for the development of visible-light-induced photocatalytic and electrocatalytic systems, which is hoped to contribute to the advancement of sustainable energy production and environmental remediation. © 2024, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item Molecular surface-dependent light harvesting and photo charge separation in plant-derived carbon quantum dots for visible-light-driven OH radical generation for remediation of aromatic hydrocarbon pollutants and real wastewater(Academic Press Inc., 2024) Meena, S.; Sethi, M.; Saini, S.; Kumar, K.; Saini, P.; Meena, S.; Kashyap, S.; Yadav, M.; Meena, M.L.; Dandia, A.; Nirmal, N.K.; Parewa, V.Despite the growing emphasis on eco-friendly nanomaterials as energy harvesters, scientists are actively searching for metal-free photocatalysts to be used in environmental remediation strategies. Developing renewable resource-based carbon quantum dots (CQDs) as the sole photocatalyst to harvest visible light for efficient pollutant degradation is crucial yet challenging, particularly for addressing the escalating issue of water deterioration. Moreover, the photocatalytic decomposition of H2O2 under visible light irradiation remains an arduous task. Based on this, we designed two types of CQDs, C-CQDs (carboxylic-rich) and A-CQDs (amine-rich) with distinct molecular surfaces. Owing to the higher amount of upward band bending induced by amine-rich molecular surface, A-CQDs efficiently harvest the visible light and prevent recombination kinetics resulting in prolonged lifetimes (25 ps), and augmented charge carrier density (35.7 × 1018) of photoexcited charge carriers. A-CQDs enabled rapid visible-light-driven photolysis of H2O2 (k = 0.058 min−1) and produced higher quantity of •OH radicals (0.158 μmol/sec) for the mineralization of petroleum waste, BETX (i.e. Benzene, Ethylbenzene, Toluene and Xylene) (k = 0.017–0.026 min−1) and real textile wastewater (k = 0.026 min−1). To assess comparative toxicities of both remediated and non-remediated real wastewater samples in a time and dose depended manner, Drosophila melanogaster was used as a model organism. The findings unequivocally demonstrate the potential of remediated wastewater for watering urban forestry. © 2024 Elsevier Inc.Item An insight into noticeable dielectric response and effect of fe doping on photocatalytic efficiency (visible light) of ZnO nanoparticles synthesized through solution precipitation for harmful textile dye degradation(Springer Science and Business Media B.V., 2024) Mahendra, K.; Fernandes, J.M.; James, A.; B.s, N.; Pattar, J.; Sunitha, D.V.; Gopal, K.; Udayashankar, N.K.Iron (Fe)-incorporated zinc oxide (ZnO) nanoparticles (NPs) were synthesized via chemical precipitation technique and studied using powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), and UV–vis diffuse reflectance spectroscopy. PXRD analysis reveals a hexagonal wurtzite structure for all the synthesized samples. UV–visible measurements demonstrate a reduction in the bandgap of ZnO with an increase in Fe concentration. The ZnO and Fe-incorporated ZnO NPs are studied for the degradation of organic textile dye under visible light irradiation. All the nanoparticles are thoroughly investigated using impedance and dielectric measurements in the frequency range of 20 Hz to 1 MHz. The results obtained are compared, interpreted, and presented in this paper. © The Author(s), under exclusive licence to Springer Nature B.V. 2024.Item Porphyrin-azoheteroarenes: synthesis, photophysical, and computational studies(Royal Society of Chemistry, 2025) Shet, S.N.; Bhat, V.G.; Swathi, S.G.; Udayakumar, U.; Shetti, V.S.Azobenzenes (Ph-N = N-Ph) are well-known photochromic compounds with widespread applications. Replacing one or both phenyl rings of azobenzenes with heteroarenes leads to a new class of compounds known as azoheteroarenes (Het-N N-Ph/Het). Azoheteroarenes have gained attention as promising alternatives to traditional azobenzenes in the field of photopharmacology due to their ability to undergo photoswitching under visible light. Interestingly, the chemistry of porphyrin-containing azoheteroarenes has been underexplored. In this study, we present the synthesis of hitherto unknown hybrid molecules: porphyrin-azopyrroles (porphyrin-N N-pyrrole) and porphyrin-azoindoles (porphyrin-N N-indole), which also feature porphyrins with five-membered meso-substituents, such as 2-furyl and 2-thienyl groups. The porphyrin-azoheteroarenes with meso-tris(2-furyl/2-thienyl) substitutions demonstrate red-shifted absorption and emission bands, more significant Stokes shifts, and smaller optical bandgaps compared to hybrids containing only meso-aryl groups. Additionally, these porphyrin-azoheteroarenes exhibit higher fluorescence emission intensities than their corresponding precursor porphyrins. © 2025 The Royal Society of Chemistry.Item Fabrication of CuxO/TiO2 hybrid nanocomposite by the synergetic effect of mixed phytoextract of agro-waste materials for enhanced visible-light-induced photocatalytic activity in degradation of ciprofloxacin(Elsevier Ltd, 2025) Shetty, P.; Shetty Kodialbail, V.The current study presents the environmentally friendly method for the synthesis of visible light active CuxO/TiO2 nanocomposite using the mixed plant extracts of areca nut exocarp (peel) and soapnut pericarp (shell) for photocatalytic degradation of ciprofloxacin, an antibiotic which is an emerging water contaminant. CuxO/TiO2 nanocomposite was synthesised by one pot method by simultaneous addition of precursors using the mixed aqueous extract. It consisted of CuO, Cu2O and TiO2 in all the crystalline phases with a band gap energy of 1.7 eV. The nanocomposite exhibited mixed morphology consisting of needle-like and particulate structures. The CuxO/ TiO2 nanocomposite facilitated 94 % degradation of 10 ppm ciprofloxacin within a span of 120 min under visible light irradiation. The CuxO/ TiO2 nanocomposite synthesized using the mixed extract exhibited superior photocatalytic activity than that synthesized solely with either areca nut peel extract or soap nut shell extract. The phyto-fabricated CuxO/ TiO2 nanocomposite showed better visible light-mediated photocatalytic activity than the phyto-fabricated CuxO, phyto- fabricated TiO2 and Degussa P-25. The kinetics of degradation followed pseudo-first order kinetic model with the rate constant of 0.0218 min?1. Thus, the phyto-fabricated CuxO/ TiO2 demonstrated a good potential as a photocatalyst to harness solar light in the treatment of wastewater contaminated with pollutants of emerging concern. © 2025 Elsevier B.V.