Faculty Publications
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Item Biohydrometallurgical methods and the processes involved in the bioleaching of WEEE(Elsevier, 2021) Minimol, M.; Shetty K, K.; Saidutta, M.B.The obsession toward the latest electronics and electrical goods has led to the generation of undesirable quantities of Waste Electrical and Electronic Equipments termed as electronic wastes (e-wastes). E-wastes, especially the printed circuit boards, are rich in their metal concentration and are considered as secondary resources for urban mining. The management of the metallic portion of these wastes is achieved through established physical, chemical, and biological treatment technologies. Biohydrometallurgy is a significant technology to address the issue in an eco-friendly mode. The different processes of biohydrometallurgy include bioleaching, bioflocculation, bioprecipitation, biosorption, biooxidation, and bioreduction. Bioleaching plays a vital role in the dissolution of metals from the solid matrix into the leaching solution using microorganisms. The different methods of bioleaching to accomplish metal recovery from e-waste are one-step bioleaching, two-step bioleaching, and spent medium bioleaching. The method to be selected depends on several growth and process factors to be successfully implemented. This chapter focuses on the methods of bioleaching and the processes involved in each of these methods to opt the most appropriate one for efficient metal recovery. Studies on biohydrometallurgy would confront the glitches involved in e-waste disposal and recycling in a sustainable manner. © 2021 Elsevier Inc. All rights reserved.Item Extraction and characterisation of cellulose microfibrils from pongamia pinnata seed shell(International Committee on Composite Materials M.Wisnom@bristol.ac.uk, 2015) Manjula, P.; Srinikethan, G.; Shetty K, K.Biodiesel is a renewable resource of energy and has gained its importance in India due to soaring oil price and largely enhanced environmental awareness. Biodiesel and other biofuels are produced from agricultural plant and plant products. Pongamia Pinnata seeds have been identified as a superior and more sustainable source of biodiesel. The process generates large amount of unused Pongamia Pinnata seed shell. The present paper reports isolation of cellulose microfibrils from Pongamia Pinnata seed shell using chlorination and alkaline extraction process. The morphology of the cellulose microfibrils was investigated by Scanning Electron Microscopy. The cellulose microfibrils had diameter in the range of 0.8-2.6 μm. The crystallinity index obtained from X-ray diffraction and spectrums from Fourier transform infrared and Nuclear magnetic resonance spectroscopy for seed shell and extracted cellulose microfibrils, showed that the chemical treatments removed most of the hemicellulose and lignin from the seed shell fibers. The thermal stability of the fibers was analysed using thermogravimetric analysis, which demonstrated that thermal stability was enhanced noticeably for cellulose microfibrils. This work provides a new approach for more effective utilisation of Pongamia Pinnata seed shell to examine their potential use as reinforcement fibres in biocomposites. © 2015 International Committee on Composite Materials. All rights reserved.Item Chromium-resistant bacteria and their environmental condition for hexavalent chromium removal: A review(2013) Narayani, M.; Shetty K, K.The anthropogenic inputs of hexavalent chromium [Cr(VI)] have increased enormously during the past few decades and has become a challenge for life on earth and hence removal of this carcinogen has become the need of the hour. Cr(VI) removal through common physicochemical techniques is highly expensive and inappropriate at low concentration. Microbial reduction of Cr(VI) to trivalent form is considered a favorable technique for Cr(VI) removal from wastewater, as it reduces the highly toxic form of Cr to less toxic form and therefore the article conveys essential fundamental information on removal of Cr(VI) by bacteria. For efficient bioremoval of Cr(VI),the main machinery of the process, the microbes, and their conditions, which decide the fate of this heavy metal, should be appropriate. Hence, the authors cover vast information about the isolation of chromium-resistant bacteria from various environment and their Cr(VI) resistance capability. An extensive report is given on information pertaining to the factors such as cell density, pH, temperature, salt concentration, oxidation-reduction potential, electron donor, oxyanions, metabolic inhibitors, and other heavy metals that influence or affect the efficient Cr(VI) removal. Cr(VI) removal by immobilized bacterial cells and their advantages has also been summarized. In transferring this technology from laboratory to a large-scale application, better understanding of all these aspects is necessary. Hence, this developing biotechnological method that encompasses fields from genetic engineering to reactor engineering demands focused research in these directions, which may lead to implementation of this technology on a larger scale and drive it toward being the most opted-for technology. © 2013 Copyright Taylor and Francis Group, LLC.Item The uptake mechanism of Cd(II), Cr(VI), Cu(II), Pb(II), and Zn(II) by mycelia and fruiting bodies of Galerina vittiformis(Hindawi Publishing Corporation 410 Park Avenue, 15th Floor, 287 pmb New York NY 10022, 2013) Damodaran, D.; Mohan Balakrishnan, R.M.; Shetty K, K.Optimum concentrations of heavy metals like copper, cadmium, lead, chromium, and zinc in soil are essential in carrying out various cellular activities in minimum concentrations and hence help in sustaining all life forms, although higher concentration of these metals is lethal to most of the life forms. Galerina vittiformis, a macrofungus, was found to accumulate these heavy metals into its fleshy fruiting body in the order Pb(II) > Cd(II) > Cu(II) > Zn(II) > Cr(VI) from 50 mg/kg soil. It possesses various ranges of potential cellular mechanisms that may be involved in detoxification of heavy metals and thus increases its tolerance to heavy metal stress, mainly by producing organic acids and phytochelatins (PCs). These components help in repairing stress damaged proteins and compartmentalisation of metals to vacuoles. The stress tolerance mechanism can be deduced by various analytical tools like SEM-EDX, FTIR, and LC-MS. Production of two kinds of phytochelatins was observed in the organism in response to metal stress. © 2013 Dilna Damodaran et al.Item Solar photocatalysis for treatment of Acid Yellow-17 (AY-17) dye contaminated water using Ag@TiO2 core-shell structured nanoparticles(2013) Khanna, A.; Shetty K, K.Wastewater released from textile industries causes water pollution, and it needs to be treated before discharge to the environment by cost effective technologies. Solar photocatalysis is a promising technology for the treatment of dye wastewater. The Ag@TiO2 nanoparticles comprising of Ag core and TiO2 shell (Ag@TiO2) have unique photocatalytic property of inhibition of electron-hole recombination and visible light absorption, which makes it a promising photocatalyst for use in solar photocatalysis and with higher photocatalytic rate. Therefore, in the present work, the Ag@TiO2 nanoparticles synthesized by one pot method with postcalcination step has been used for the degradation of Acid Yellow-17 (AY-17) dye under solar light irradiation. The Ag@TiO2 nanoparticles were characterized using thermogravimetric-differential thermal analysis, X-ray diffraction, transmission electron microscopy, selected area electron diffraction, and energy dispersive X-ray analysis. The catalyst has been found to be very effective in solar photocatalysis of AY-17, as compared to other catalysts. The effects of pH, catalyst loading, initial dye concentration, and oxidants on photocatalysis were also studied. The optimized parameters for degradation of AY-17 using Ag@TiO2 were found to be pH 3, dye/catalyst ratio of 1:10 (g/g), and 2 g/L of (NH4)2S2O8 as oxidant. Efficient decolorization and mineralization of AY-17 was achieved. The kinetics of color, total organic carbon, and chemical oxygen demand removal followed the Langmuir-Hinshelwood model. Ag@TiO2 catalyst can be reused thrice without much decline in efficiency. The catalyst exhibited its potential as economic photocatalyst for treatment of dye wastewater. © 2013 Springer-Verlag Berlin Heidelberg.Item Biodegradation of phenol using immobilized nocardia hydrocarbonoxydans in a pulsed plate bioreactor: Effect of packed stages, cell carrier loading, and cell acclimatization on startup and steady-state behavior(2013) Shetty K, K.; Yarangali, S.B.; Srinikethan, G.The effect of the number of stages and cell carrier loading on the steady-state and startup performance of a continuous pulsed plate bioreactor with glass beads as the cell carrier material for biodegradation of phenol in wastewater using immobilized Nocardia hydrocarbonoxydans has been studied. It was found that the performance of the pulsed plate bioreactor during startup and at steady state can be improved by an increase in cell carrier loading, number of stages, total plate stack height, and with a decrease in plate spacing. The startup time for the continuous bioreactor can be decreased by increasing the number of preacclimatization steps for the cells. The attainment of steady effluent phenol concentration can be considered as an indication of steady state of the continuous bioreactor, as when phenol concentration attained a steady value, biofilm thickness, and the attached biomass dry weight also attained a constant value. © 2013 Copyright Taylor and Francis Group, LLC.Item Effect of chelaters on bioaccumulation of Cd (II), Cu (II), Cr (VI), Pb (II) and Zn (II) in Galerina vittiformis from soil(2013) Damodaran, D.; Shetty K, K.; Raj Mohan, B.Remediation of heavy metal contaminated soil and water streams are of great necessity as heavy metals are toxic and pose hazardous ecological impacts. Low cost mitigation measures like phytoremediation and mycoremediation are commonly employed. Mycoremediation using macro fungi (mushroom) have proven to provide effective tolerance using an efficient accumulation mechanism in removing heavy metals from soil. The current paper reports the heavy metal remediation potential of macro fungi on soil artificially contaminated with 50mgkg-1 of Cu (II), Cd (II), Cr (VI), Pb (II), and Zn (II) ions. Galerina vittiformis belonging to Strophariacea family was found to be effective in removing the heavy metal from the soil under study within 30 days. Both chemical and biological chelaters at 1, 5, and 10mmolkg-1 concentrations were found to increase the mycoremediation potential of the organism. This study showed that G. vittiformis are efficient in remediating heavy metal from contaminated soil and that their remediation potential can be enhanced by the addition of chelaters. © 2013 Elsevier Ltd.Item Solar light induced photocatalytic degradation of Reactive Blue 220 (RB-220) dye with highly efficient Ag@TiO2 core-shell nanoparticles: A comparison with UV photocatalysis(2014) Khanna, A.; Shetty K, K.Ag core-TiO2 shell (Ag@TiO2) structured nanoparticles with Ag to TiO2 molar ratio of 1:1.7 were synthesized using one pot synthesis method and post calcination was carried out at 450°C for 3h to convert it from amorphous to crystalline form. The Ag core and TiO2 shell formation was confirmed by TEM and AFM. The particle size analysis revealed the average size of Ag@TiO2 as approximately around 30nm. EDS spectra showed the presence of O, Ag, and Ti elements. The improvement in optical properties was proved by DRS which showed significant red shift by Ag core in visible region. Ag@TiO2 exhibited better photocatalytic activity as compared to Degussa P25-TiO2, synthesized TiO2, and the Ag doped TiO2 photocatalysts under UV and solar light irradiation for degradation of Reactive Blue 220 (RB-220) dye. Higher rate of photocatalysis of RB-220 with Ag@TiO2 was obtained under solar light irradiation as compared to UV light irradiation, confirming the capability of the catalyst to absorb both UV and visible light. The kinetics of degradation of dye was found to follow modified Langmuir Hinshelwood (L-H) kinetic model. Ag@TiO2 can be recycled without much decline in the efficacy. Ag@TiO2 has been found to be the effective photocatalyst for degradation of water contaminated with azo dyes under both UV and solar light irradiations. © 2013 Elsevier Ltd.Item Uptake of certain heavy metals from contaminated soil by mushroom-Galerina vittiformis(Academic Press, 2014) Damodaran, D.; Shetty K, K.; Raj Mohan, B.Remediation of soil contaminated with heavy metals has received considerable attention in recent years. In this study, the heavy metal uptake potential of the mushroom, Galerina vittiformis, was studied in soil artificially contaminated with Cu (II), Cd (II), Cr (VI), Pb (II) and Zn (II) at concentrations of 50 and 100. mg/kg. G. vittiformis was found to be effective in removing the metals from soil within 30 days. The bioaccumulation factor (BAF) for both mycelia and fruiting bodies with respect to these heavy metals at 50. mg/kg concentrations were found to be greater than one, indicating hyper accumulating nature by the mushroom. The metal removal rates by G. vittiformis was analyzed using different kinetic rate constants and found to follow the second order kinetic rate equation except for Cd (II), which followed the first order rate kinetics. © 2013 Elsevier Inc.Item Reduction of hexavalent chromium by a novel Ochrobactrum sp. - microbial characteristics and reduction kinetics(Wiley-VCH Verlag, 2014) Narayani, M.; Shetty K, K.A Gram negative hexavalent chromium (Cr(VI)) reducing bacteria, Ochrobactrum sp. Cr-B4 (genbank accession number: JF824998) was isolated from the aerator water of an activated sludge process of a wastewater treatment facility of a dye and pigment based specialty chemical industry. It showed a resistance for 1000mgL-1 Cr(VI). It exhibited resistance against other heavy metal ions like Ni2+ (900mgL-1), Cu2+ (500mgL-1), Pb2+ (800mgL-1), and Cd2+(250mgL-1), Zn2+ (700mgL-1), Fe3+ (800mgL-1), and against selected antibiotics. Cr-B4 could efficiently reduce 200mgL-1 Cr(VI) completely in nutrient and LB media and could convert Cr(VI) to Cr(III) efficiently. Cr(VI) reduction in nutrient media followed allosteric enzyme kinetics with Km values of 59.39mgL-1 and Vmax values of 47.03mgL-1h-1. The reduction in LB media followed Michaelis-Menten kinetics with Km values of 99.52mgL-1 and Vmax of 77.63mgL-1h-1. Scanning electron micrograms revealed the presence of extracellular polymeric secretions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.