Journal Articles
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884
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Item Studies on the effect of pH, temperature and metal ions on the production of pectinase from tamarind kernel powder by submerged fermentation using Aspergillus foetidus (NCIM 505)(2010) JagadeeshBabu, P.E.; Viswanathan, R.Filamentous fungi Aspergillus foetidus NCIM 505 was studied for its capacity to produce exo-pectinase in submerged fermentation (SMF) from a new substrate of tamarind kernel powder (TKP). The process was further studied to optimize the initial operating variables like pH, time and temperature. Maximum pectinolytic activity was reached at 72 h of growth and the best fungal strain was found to be A. foetidus NCIM 505. Further, to increase the production rate of pectinase, the effects of metal ions were studied. Metal ions like Cu ++, Mg++, Fe++, Co++ and Zn ++ at different concentrations were used. © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.Item Equilibrium and kinetic study for the removal of malachite green using activated carbon prepared from Borassus flabellofer male flower(2010) JagadeeshBabu, P.E.; Kumar, V.; Visvanathan, R.Activated carbon was prepared from dried Borassus flabellofer male flower and batch adsorption experiments were conducted to study its potential to remove malachite green (MG) dye. The process was further optimized by studying the operating variables like initial pH of the stock solution, activation temperature, initial dye concentration, adsorbent loading and contact time. The optimized pH and activation temperatures were found to be 7.55 and 450.C respectively, where further analysis was made using these optimal variables. Linear, Freundlich and Langmuir isotherms were studied and it was found that the Langmuir isotherms have the highest correlation coefficients compared to the others. Further, the sorption kinetics were analysed using pseudo-first-order and pseudo-second-order kinetic models. The data showed that the second-order equation was the more appropriate, which indicate that the intra-particle diffusion is the rate limiting factor. © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.Item Drag reduction in co-current down flow packed column using xanthan gum(2010) Iyyaswami, I.; JagadeeshBabu, P.E.; Chitra, M.; Murugesan, T.Drag reduction is one of the most important techniques for reducing energy consumption in a packed bed contactor. The present work involves an experimental investigation on flow regime transition for air-water system with and without drag reducing agent (DRA), two-phase pressure drop, friction factor and drag reduction using xanthan gum as DRA. Drag reduction was quantified from the two-phase pressure drop data. Based on the present observations it was found that the percentage drag reduction increases with an increase in the concentration of DRA and it is only effective in the range of 300 ppm to 800 ppm. The experimental results indicate that a maximum of 80% drag reduction was achievable using xanthan gum (800 ppm) as DRA. Furthermore, the experimental data were validated with the available literature correlations. © 2010 Korean Institute of Chemical Engineers, Seoul, Korea.Item Bed depth service time model for the biosorption of reactive red dye using the Portunus sanguinolentus shell(2010) JagadeeshBabu, P.E.; Krishnan, R.; Singh, M.Biosorption is an efficient and regenerative technique that often uses low-cost adsorbent materials, particularly for the treatment of wastewaters containing dyes and heavy metals. This study investigates the ability of crab shell (Portunus sanguinolentus) to remove reactive red dye in a packed bed up-flow column (internal diameter 2 cm; height 35 cm). Crab shell has high surface area (after proper size reduction) and high regenerative capacity. The experiments were performed with different bed heights (20 and 30 cm) and using different flow rates (12 and 17 ml/min) in order to obtain experimental breakthrough curves. The bed depth service time (BDST) model was used to analyze the experimental data and the model parameters were evaluated. The column regeneration studies were carried out for five different sorption-desorption cycles. The elutant used for the regeneration of the sorbent was 0.01 M EDTA (disodium) solution at pH 9.8 adjusted using NH4OH. This solution was found to have the best bed regeneration capacity and could be reused for several sorption-desorption cycles. The elution efficiency was greater than 99.1% in all seven cycles. Continuous use of the crab shell leads to a decrease in the adsorptive performance, as observed by the breakthrough curves becoming flatter and also because of a broader mass transfer zone. © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.Item Kinetics of esterification of acetic acid with methanol in the presence of ion exchange resin catalysts(2011) JagadeeshBabu, P.E.; Sandesh, K.; Saidutta, M.B.Esterification kinetics of acetic acid with methanol was studied with solid acid catalyst in an isothermal batch reactor at 333-353 K. Different types of ion exchange catalyst (Indion 130, Indion 190, and Amberlyst 15 wet) were used for the esterification of acetic acid. It was found that Indion 130 was an effective catalyst for acetic acid esterification. The effects of stirrer speed, reaction temperature, initial reactant concentration, and catalyst loading on reaction rate were investigated and optimized. Temperature dependence of the reaction rates and activation energies was determined by an Arrhenius plot. A complete kinetic equation for describing the reaction catalyzed by Indion 130 was developed. This equation can be used in the simulation and design of the catalytic distillation column for the synthesis of methyl acetate. © 2011 American Chemical Society.Item Synthesis and characterization of temperature sensitive P-NIPAM macro/micro hydrogels(Elsevier B.V., 2011) JagadeeshBabu, P.E.; Suresh Kumar, R.; Maheswari, B.A thermo responsive macro porous poly(N-isopropylacrylamide) hydrogel was synthesized using free radical polymerization. The reaction was optimized by varying the reaction temperature, monomer, cross-linker and initiator based on the strength and swelling characteristics of the hydrogel. The morphology of the macro hydrogel was observed using scanning electron microscope (SEM). The swelling behavior of the macro hydrogel was performed gravimetrically and found that the gel synthesized at 36 °C had maximum deswelling ratio of 34.5 (-). These optimized values were further used to synthesis micro hydrogels using water-oil (w/o) emulsion technique. The morphology of the micro hydrogels were observed through SEM. Effect of water-oil ratio and stirrer speed on the mean particle size of the micro hydrogels were studied. Micro hydrogels synthesized at 1:1.5. w/o ratio and at 800. rpm had perfect spherical shape and had least particle mean diameter of 0.74 ?m, with SD of 0.5. Dye release kinetics with respect to temperature and time were studied using methylene blue solution. The release kinetic studies of micro hydrogel showed higher sustained release for 56. h compared to the macro hydrogel. © 2011 Elsevier B.V.Item Bio-conjugation of Bacillus Fastidiosus-Uricase with methoxy polyethylene glycol derivative and study of physiochemical properties(2012) Nanda, P.; JagadeeshBabu, P.E.; Tekalkote, S.; Kunnummal, B.M.; Kaleekkal, N.Uricase (EC 1.7.3.3, UC) is an enzyme belonging to the class of oxidoreductases and catalyses the oxidation of uric acid to allantoin, carbon dioxide and hydrogen peroxide. In this present work, Uricase from Bacillus fastidisous was conjugated with methoxypolyethyleneglycol p-nitrophenyl carbonate (mPEG-np) a polyethylene glycol derivative, in order to improve the pharmaceutical properties of therapeutic enzyme uricase. The PEGylated conjugates (uricase-mPEG-np) were synthesized using various ratios of uricase and mPEG-np to get maximum residual activity. The PEGylated uricase showed maximum residual uricolytic activity of 90.9% compared to the unmodified uricase, which was achieved at a ratio of 1:17 of uricase to mPEG-np. PEGylated uricase was further characterized using SDS-PAGE to determine its final molecular weight and approximate number of mPEG molecules attached. The result showed that the molecular weight was increased to 79.4 KDa and the number of mPEG molecules bound per subunit of uricase was approximately 9. Stability of the PEGylated uricase at various temperature and pH was studied and found to be 32°C and pH of 9.0. Further the mechanism of binding and possible sites of binding were studied using molecular modeling and docking software tool ArgusLab 4.0.1 and the two-dimensional image of docked uricase were generated.Item Rapid removal of cobalt (II) from aqueous solution using cuttlefish bones; Equilibrium, kinetics, and thermodynamic study(2013) Sandesh, K.; Suresh Kumar, R.; JagadeeshBabu, P.E.The objective of this study is to assess the adsorption potential of cobalt (II) using cuttlefish bones. The bones were treated with 0.01 N HCl to enhance the heavy metal uptake. The adsorbent was characterized using scanning electron microscope and energy dispersive X-ray spectrometer. An adsorption study was conducted in a batch system to optimize process variables such as initial concentration of cobalt (II), pH, sorbent loading, particle size, process temperature, and contact time. The optimal pH was found to be 9. The kinetic data followed the pseudosecond-order kinetic model, and the equilibrium time was found to be 20 min. In the first minute of the adsorption process, 50% of the cobalt (II) was adsorbed by the cuttle bones. Adsorption isotherms were expressed by the Langmuir and Freundlich adsorption models. The Langmuir adsorption model fits the experimental data reasonably well compared with the Freundlich model. The maximum adsorption capacity of this new sorbent was found to be 76.6 mg g-1 at 40 °C. Thermodynamic parameters, including the Gibbs free energy (?Go), enthalpy (?Ho), and entropy (?So), indicated that the adsorption of cobalt (II) by cuttlefish bones was feasible and endothermic at a temperature range of 20-40 °C. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.Item Reactive distillation using an ion-exchange catalyst: Experimental and simulation studies for the production of methyl acetate(2013) Sandesh, K.; JagadeeshBabu, P.E.; Math, S.; Saidutta, M.B.In this study, the performance of a packed-bed reactive distillation (RD) column for the production of methyl acetate (MeOAc) using an ion-exchange catalyst and simulation of the same using CHEMCAD were analyzed. An ion-exchange catalyst, Indion 190, was used in this study. The performance of the RD column was evaluated based on the MeOAc concentration in the top product. Both steady- and unsteady-state behavior of the column was simulated using CHEMCAD, and the results were experimentally validated. The process parameters, viz., reboiler temperature, enriching temperature, reactor temperature, catalyst loading, molar ratio of the reactant, and flow rate of reactants, were studied, and the optimal values were found to be 73 C, 56 C, 72 C, 100 g, 1:2, and 15 mL/min, respectively. Feed locations of acid and alcohol to the reactor that gave maximum MeOAc concentration in the top product were determined. A mathematical model based on the rigorous calculation using SCDS (used to calculate the nonideal K value) was used to simulate the RD in CHEMCAD. The simulated values were found to deviate from the experimental values within ±5-10%. © 2013 American Chemical Society.Item Synthesis and characterization of polysialic acid-uricase conjugates for the treatment of hyperuricemia(Kluwer Academic Publishers, 2014) Punnappuzha, A.; JagadeeshBabu, P.E.; Nishith, R.S.; Hadigal, S.; Shenoy, P.G.Uricase, an enzyme used for the treatment of hyperuricemia, is conjugated with polysialic acid (PSA) of average molecular weight of 10 kDa by reductive amination in presence of NaCNBH3 in order to improve its pharmacological properties. Polysialylation with 50-,100-,150- and 200-fold molar excess of PSA increased the percentage substitution of the free amino groups on enzyme surface (46, 66, 78 and 80 % respectively). The SDS-PAGE is used to visualize the conjugates with increased molecular weight and it retained almost 65 % of their initial specific activity after conjugation. The stability studies at physiological condition reveals improved stability and activity than the native enzyme. The apparent KM of the enzyme has increased slightly from 4.18 × 10-5 M to 5.46 × 10-5 M suggesting that the affinity of the substrate to the enzyme has not been altered to a higher extent. The conjugates, when probed against anti-uricase antibodies generated in rabbit, showed a clean decline in the affinity by 35 % and also have retained double the catalytic activity than that of the native enzyme after exposure to antiserum. The results suggest that uricase-PSA conjugates can be used as an alternative to the conventional synthetic polymer-enzyme conjugates. © 2014 Springer Science+Business Media New York.
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