Faculty Publications

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    Nano Fe3O4@APTES@Ni(OH)2 as a catalyst for alcohol oxidation
    (Royal Society of Chemistry, 2015) Bhat, P.B.; Badekai Ramachandra, B.R.
    A nanorod shaped nickel hydroxide coated ferrite nanocatalyst was synthesized by a traditional co-precipitation method. The particle size of the nanoferrite was tuned using a variable surfactant ratio to achieve a high surface area. A very high BET surface area (334.55 m2 g-1) was achieved for particles with sizes of 40-130 nm. The superparamagnetic reusable catalyst was found to be active for the selective liquid phase oxidation of alcohols with hydrogen peroxide as a mild oxidant. Nickel hydroxide acted as a Bronsted base working in synergy with the nanoferrite catalyst for alcohol oxidation. The catalytic system was found to catalyse primary and secondary alcohols efficiently (86%) to their corresponding carbonyls in good yields. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015.
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    Solar light mediated photocatalytic degradation of phenol using Ag core - TiO2 shell (Ag@TiO2) nanoparticles in batch and fluidized bed reactor
    (Elsevier Ltd, 2016) Shet, A.; Shetty K, K.V.
    Ag@TiO2 nanoparticles were synthesised using one pot method followed by calcination at 450 °C for 3 h and were tested for their photocatalytic efficacy in degradation of phenol both in free and immobilized form under solar light irradiation through batch experiments. Ag@TiO2 nanoparticles were found to be effective in solar photocatalytic degradation of phenol. The effect of factors such as pH, initial phenol concentration and catalyst loading on phenol degradation were evaluated and these factors were found to influence the process efficiency. The optimum values of these factors were determined to maximize the phenol degradation. The efficacy of nanoparticles immobilized on cellulose acetate film was inferior to that of free nanoparticles in solar photocatalysis due to light penetration problem and diffusional limitations. The performance of fluidized bed photocatalytic reactor operated under batch with recycle mode for solar photocatalysis of phenol with immobilized Ag@TiO2 nanoparticles was evaluated for large scale application. The performance was found to be dependent on catalyst loading and the optimum is governed by active catalyst sites and light penetration limitations. The photocatalytic degradation of phenol by Ag@TiO2 nanoparticles was only marginally influenced by the presence of small traces of chloride ions. Ag@TiO2 showed a better efficacy as solar photocatalyst than as UV photocatalyst in degradation of phenol. Solar light irradiation is recommended because solar energy, a readily available form of energy can be effectively harnessed for energy efficient, environment friendly and cost effective process. The kinetics of degradation of phenol was found to follow the nth order kinetics with order, n = 2.19 for solar photocatalysis. © 2016 Elsevier Ltd.
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    Performance enhancement of polysulfone ultrafiltration membrane using TiO2 nanofibers
    (Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2016) Nair, A.K.; Shalin, P.M.; JagadeeshBabu, P.E.
    Titanium dioxide nanofibers were synthesized via alkaline hydrothermal method using TiO2 nanopowder. The hydrothermal method was optimized by studying the operating variables to obtain nanosized TiO2 fibers. These nanofibers were used to make composite polysulfone ultrafiltration membranes along with polyethylene glycol as pore forming agent. The obtained samples were characterized using scanning electron microscope, X-ray diffraction, and attenuated total reflectance infrared spectroscopy. Contact angle measurements were used to estimate hydrophilicity of the membrane. Performance of the membrane was analyzed using pure water flux studies and antifouling studies with bovine serum albumin as the standard protein for rejection. The composite membranes exhibited better performance in both permeability and antifouling property. © 2015 Balaban Desalination Publications. All rights reserved.
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    Ag-TiO2 nanoparticles for photocatalytic degradation of lomefloxacin
    (Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2016) Kulkarni, R.M.; Malladi, R.S.; Hanagadakar, M.S.; Doddamani, M.R.; Bhat, K.U.
    The photocatalytic activity of silver-doped TiO2 (Ag-TiO2) nanoparticles was studied by photocatalytic degradation of lomefloxacin (LMF) using a photoreactor with a mercury lamp (PHILIPS, TUV 8 W T5, Emax = 254 nm). The 1 and 2% silver-doped TiO2 nanoparticles were synthesized by liquid impregnation (LI) method. The resulting nanoparticles were characterized by surface analytical methods such as X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray analysis and transmission electron microscope (TEM). The study shows 2% Ag-TiO2 nanoparticles exhibited better results (95% degradation) in 1 h for the degradation of lomeofloxacin compared to 1% Ag-TiO2 and pure TiO2. XRD analysis indicated that the crystallite size of TiO2 was 17.00 nm, while the crystallite size of 1% Ag-TiO2 and 2% Ag-TiO2 was 13.07 to 14.17 nm. TEM images show the particle size of Ag-TiO2 nanoparticles were in the range 40–45 nm in length and 10–15 nm in breadth. Pseudo-first-order rate constants were found to decrease with increase in pH. The effect of UV intensity, catalyst dosage and initial concentration of LMF on the degradation rate were also studied and elaborately discussed. © 2015 Balaban Desalination Publications. All rights reserved.
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    Selenium Biosorption and Recovery by Marine Aspergillus terreus in an Upflow Bioreactor
    (American Society of Civil Engineers (ASCE) onlinejls@asce.org, 2016) Raja, C.P.; Jacob, J.M.; Mohan Balakrishnan, R.M.
    Experiments were conducted to study the Selenium (Se) biosorption and recovery by marine Aspergillus terreus in an upflow bioreactor for a period of 8 days. The Se tolerance of the marine fungus was initially confirmed by visual and microscopic observations that evinced intact fungal cells in an Se-amended medium with sparse changes in the spore texture and cellular number by the seventh day of biosorption studies in the upflow bioreactor. Further, the effect of pH and contact time on the percentage of Se biosorption, in an upflow bioreactor containing fungal pellets, was investigated. It was analyzed that pH ranges of 6-7 and a contact time of 5 days resulted in 85-87% biosorption of Se by the fungal biomass. The interaction of the fungus with the induced Se stress in the medium was monitored regularly for studying the uptake of the metalloid and the possible biosynthesis of Se nanoparticles. Analyses using ultraviolet visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) studies revealed the formation of crystalline Se nanocrystals with an average diameter of 500 nm on the fungal cell wall. Fourier transform infrared (FTIR) spectroscopic analysis indicated the possible involvement of fungal protein groups that aid the binding of the biosorbed Se nanoparticles on to the fungal cell wall. © 2015 American Society of Civil Engineers.
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    Microbial disinfection of water with endotoxin degradation by photocatalysis using Ag@TiO2 core shell nanoparticles
    (Springer Verlag service@springer.de, 2016) Sreeja, S.; Shetty K, K.V.
    The studies on photocatalytic disinfection of water contaminated with Escherichia coli using Ag core and TiO2 shell (Ag@TiO2) nanoparticles under UV irradiation showed that these nanoparticles are very efficient in water disinfection both in their free and immobilised form. Complete disinfection of 40 × 108 CFU/mL could be achieved in 60 min with 0.4 g/L catalyst loading and in 35 min with 1 g/L catalyst loading. Ag@TiO2 nanoparticles were found to be superior to TiO2 nanoparticles in photocatalytic disinfection of water. Kinetics of disinfection followed Chick’s law, and the pseudo-first-order rate constant was 0.0168 min?1 for a catalyst loading of 0.1 g/L. Disinfection of water and degradation of endotoxins (harmful disinfection residual) occurred simultaneously during photocatalysis thereby making the treated water safe for use. Endotoxin degradation showed a shifting order of kinetics. The rate of photocatalysis with nanoparticles immobilised in cellulose acetate film was marginally lower as compared to that of free nanoparticles. Negligible Ag ion leakage and re-growth of cells post-photo-catalytic treatment of water confirmed that complete disintegration of E. coli occurred during photocatalysis making the treated water safe for use. Therefore, Ag@TiO2 nanoparticles have a potential for large-scale application in drinking water treatment plants and household purification units. © 2016, Springer-Verlag Berlin Heidelberg.
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    Hydrous Cerium Oxide Nanoparticles Impregnated Enteromorpha sp. for the Removal of Hexavalent Chromium from Aqueous Solutions
    (American Society of Civil Engineers (ASCE) onlinejls@asce.org, 2016) Selvasembian, S.; Selvaraju, N.; Raj Mohan, B.; Muhammed Anzil, P.K.; Amith, K.D.; Ushakumary, E.R.
    A novel nanobiocomposite, hydrous cerium oxide nanoparticles impregnated Enteromorpha sp. (HCONIE) was used effectively for the adsorption of Cr(VI) from aqueous solutions. The chemical and structural characteristics of the nanobiocomposite were investigated using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analysis. Adsorption studies were determined as a function of pH, contact time, initial concentration of Cr(VI), HCONIE dose, and temperature. The equilibrium adsorption data were modeled using two parameter isotherms, including Langmuir, Freundlich, Dubinin-Radushkevich (D-R), Temkin, Jovanovic, Halsey, and Harkin-Jura. Adsorption data were well described by the Freundlich and Halsey isotherm. The kinetics data were analyzed using adsorption kinetic models like the pseudo-first-order, pseudo-second-order and intraparticle diffusion equation. Kinetic data showed good agreement with the pseudo-second-order kinetic model. The obtained thermodynamic parameters showed that the adsorption of Cr(VI) onto the HCONIE was exothermic in nature. The presence of foreign ions showed a decreased effect on the adsorption capacity of HCONIE towards Cr(VI) removal. The desorption study was carried out with 0.1 and 0.5 M of three different desorbing agents. The study suggests that HCONIE nanobiocomposite could be used for the removal of Cr(VI) from aqueous solution. © 2015 American Society of Civil Engineers.
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    Photocatalytic degradation of phenol using Ag core-TiO2 shell (Ag@TiO2) nanoparticles under UV light irradiation
    (Springer Verlag service@springer.de, 2016) Shet, A.; Shetty K, K.V.
    Ag@TiO2 nanoparticles were synthesized by one pot synthesis method with postcalcination. These nanoparticles were tested for their photocatalytic efficacies in degradation of phenol both in free and immobilized forms under UV light irradiation through batch experiments. Ag@TiO2 nanoparticles were found to be the effective photocatalysts for degradation of phenol. The effects of factors such as pH, initial phenol concentration, and catalyst loading on phenol degradation were evaluated, and these factors were found to influence the process efficiency. The optimum values of these factors were determined to maximize the phenol degradation. The efficacy of the nanoparticles immobilized on cellulose acetate film was inferior to that of free nanoparticles in UV photocatalysis due to light penetration problem and diffusional limitations. The performance of fluidized bed photocatalytic reactor operated under batch with recycle mode was evaluated for UV photocatalysis with immobilized Ag@TiO2 nanoparticles. In the fluidized bed reactor, the percentage degradation of phenol was found to increase with the increase in catalyst loading. © 2015, Springer-Verlag Berlin Heidelberg.
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    Photocatalytic water disinfection under solar irradiation by Ag@TiO2 core-shell structured nanoparticles
    (Elsevier Ltd, 2017) Sreeja, S.; Shetty K, V.K.
    The Ag core-TiO2 shell structured (Ag@TiO2) nanoparticles were found to be efficient in the disinfection of water under solar light irradiation both in free and immobilized form. Complete disinfection of 40 ? 108 CFU/mL Escherchia coli cells was achieved in 15 min by solar photocatalysis with 0.4 g/L Ag@TiO2 catalyst loading. Ag@TiO2 nanoparticles were found to be superior to TiO2 nanoparticles in solar disinfection. Photocatalysis rate was found to increase with increase in catalyst loading and with decrease in cell concentration. Ag@TiO2 nanoparticles showed their efficacy in the degradation of endotoxin, a harmful disinfection byproduct. Kinetics of solar disinfection with Ag@TiO2 nanoparticles followed Chick's law. The kinetics of endotoxin degradation followed zero order kinetics at high concentrations of endotoxin. However at lower concentrations, rate followed a nth order model with n = 6.99. A lower rate of photocatalytic disinfection with Ag@TiO2 nanoparticles immobilized on cellulose acetate as compared to that in their free form was observed, owing to diffusional and light penetration limitations. The re-growth of cells after photocatalytic disinfection was below the detectable limits, thus proving the potential of the process to produce safe drinking water. Ag@TiO2 nanoparticles can find potential application in solar water disinfection and the process which harnesses the solar energy may prove to be energy efficient and economical, thus can be easily adopted for large scale applications and portable drinking water treatment units for domestic applications. © 2017 Elsevier Ltd
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    The effective role of alkali earth/alkali ratio on formation HCA nano particles for soda lime phospho silicate glass system
    (Elsevier Inc, 2017) Kiran, P.; Ramakrishna, V.; Udayashankar, N.K.; Shashikala, H.D.
    In the present work, we report on the effect of the CaO/Na2O ratio on Non-Bridging Oxygen/Bridging Oxygen (NBO/BO) ratio for sol-gel synthesised 58SiO2-(38-x)CaO-xNa2O-4P2O5 glasses and establish the correlation between Hydroxy Carbonated Apatite layer (HCA) forming ability and the dissolution behaviour in simulated body fluid (SBF) solution. Thermal stabilities were calculated as 221, 135, 153 and 77 °C respectively. It is inferred that thermal stabilities varied nonlinearly with CaO/Na2O ratio. Similarly NBO/BO ratios were obtained using Raman spectroscopic analysis as 0.6293, 0.7917, 0.2264 and 0.3513, respectively. All samples were soaked in the SBF solution for 7 days. The calculated weight losses of these samples were 55.32, 69.13, 18.09 and 20.08 for the corresponding NBO/BO ratios. The decrease in CaO/ Na2O ratio led to nonlinear variation of the NBO/BO ratios. Consequently the non linear variation in NBO/BO ratio led to the nonlinear variation of HCA forming ability of SBF treated samples. © 2017 The Authors