Dinesh Kirupha - Academia.edu (original) (raw)

Papers by Dinesh Kirupha

Separation Science and Technology, 2012

Novel polyamides bearing pyridyl and azomethine groups as pendant pyridylformylimino groups along... more Novel polyamides bearing pyridyl and azomethine groups as pendant pyridylformylimino groups along with thioamide moieties in the polymer backbone were synthesized using 4-pyridylformylimino-N-(phenyl,2′,5′-dicarboxylic acid) with 4,4′-(bisthiourea)benzidine and 4,4′- diaminodiphenyl methane through one pot phosphorylation polymerization technique. The optimization of experimental conditions and parameters including pH, adsorbent dosage, contact time, and initial metal ion concentration for the removal of heavy metal has also been investigated. Kinetic studies showed that the pseudo second order rate equation fits well with experimental values. The FT-IR spectrum indicated that the pyridine, amide, amide carbonyl, and azomethine groups were the major binding sites with metal ions. The maximum adsorption capacities of the resin for Cu(II) and Pb(II) evaluated from Langmuir models were 389.9 and 403.1 mg/g, respectively. Desorption studies revealed that Cu(II) and Pb(II) can be easily removed by treating metal ion adsorbed resins with 0.1 M H2SO4 or 0.1 M HCl. The adsorption-desorption process was a reversible process, which indicates that the polyamides are promising adsorbents for heavy metal removal from aqueous medium.

Separation Science and Technology, 2011

We used a novel approach to purify Pleurotus ostreatus laccase using the three phase partitioning... more We used a novel approach to purify Pleurotus ostreatus laccase using the three phase partitioning (TPP) methodology. The aim of our research was to study the effect of TPP parameters on laccase purity and yield. The response surface methodology (RSM) has been applied to design the experiments to evaluate the interactive effects of the three most important operating variables: ammonium sulphate saturation (w/v) (20–80%), ratio of crude extract to t-butanol (v/v) (1:1 to 1:3), and temperature (20–60°C). Using this methodology, the optimum values for the critical components were obtained as follows: ammonium sulphate saturation (w/v), 50–60%; ratio of crude extract to t-butanol (v/v) 1.0:1.8; temperature 42–45°C, respectively. Under optimal conditions, the experimental laccase yield and purity was 184% and 7.22-fold, respectively. SDS-PAGE and RP-HPLC revealed that the laccase was purified by TPP. The determination coefficients (R2) were 0.9891 and 0.9728 for laccase purity and yield, respectively, indicating an adequate degree of reliability in the model. To our knowledge, the present work demonstrates for the first time the successful application of RSM to TPP.

Bioresource Technology, 2011

In this study, a two-step process was developed to produce biodiesel from Calophyllum inophyllum ... more In this study, a two-step process was developed to produce biodiesel from Calophyllum inophyllum oil. Pre-treatment with phosphoric acid modified β-zeolite in acid catalyzed esterification process preceded by transesterification which was done using conventional alkali catalyst potassium hydroxide (KOH). The objective of this study is to investigate the relationship between the reaction temperatures, reaction time and methanol to oil molar ratio in the pre-treatment step. Central Composite Design (CCD) and Response Surface Methodology (RSM) were utilized to determine the best operating condition for the pre-treatment step. Biodiesel produced by this process was tested for its fuel properties.

Brazilian Journal of Chemical Engineering, 2010

... Ajmal, M., Rao, RA, Anwar, S., Ahmad, J. and Alunad, R., Adsorption studies on rice husk: Rem... more ... Ajmal, M., Rao, RA, Anwar, S., Ahmad, J. and Alunad, R., Adsorption studies on rice husk: Removal and recovery of Cd (II) from ... Horsfall, M., Spiff, AI and Abia, AA, Studies on the influence of mercaptoacetic acid (MAA) modification of cassava (Manihot sculenta cranz) waste ...

Desalination, 2011

In the present study, cashew nut shell(CNS) was investigated as a biosorbent for the removal of c... more In the present study, cashew nut shell(CNS) was investigated as a biosorbent for the removal of copper ions from aqueous solutions. Batch experiments were carried out to investigate the effect of solution pH, CNS concentration, contact time, initial copper(II) ion concentration and temperature on sorption efficiency. The copper adsorption was favored with maximum adsorption at pH 5.0. The percentage of copper ion removal onto the CNS was decreased with increasing temperature. Biosorption equilibrium time was observed in 30 min. The equilibrium adsorption data were fitted to Langmuir and Freundlich adsorption isotherm models and the model parameters were evaluated. The kinetics of copper(II) ion was discussed using four kinetic models, the pseudo-first-order, the pseudo-second-order, the Elovich kinetic model and the intra-particle diffusion models. It was shown that the adsorption of copper ions could be described by the pseudo-second order kinetic model. Thermodynamic quantities such as Gibbs free energy (∆Go), the enthalpy (∆Ho) and the entropy change of sorption (∆So) have also been evaluated and it has been found that the sorption process was feasible, spontaneous and exothermic in nature. The results showed that CNS could be employed as a low-cost alternative adsorbent for the removal of copper ions from aqueous solutions.

Chemical Engineering Journal, 2011

The adsorption behavior of nickel(II) from aqueous solution onto agricultural waste such as cashe... more The adsorption behavior of nickel(II) from aqueous solution onto agricultural waste such as cashew nut shell (CNS) was investigated as a function of parameters such as solution pH, CNS dose, contact time, initial nickel(II) concentration and temperature. The Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models were applied to describe the equilibrium isotherms using nonlinear regression analysis. The equilibrium data fits well for the both Langmuir and Freundlich adsorption isotherms. The Langmuir monolayer adsorption capacity of CNS was found to be 18.868 mg/g. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° have also been evaluated and it has been found that the sorption process was feasible, spontaneous and exothermic in nature. Pseudo-first-order, pseudo-second-order and Elovich kinetic models were used to describe the kinetic data and the rate constants were evaluated. The result of the kinetic study shows that the adsorption of nickel(II) could be described by the pseudo-second-order equation, suggesting that the adsorption process is presumably chemisorption. The adsorption process was found to be controlled by both surface and pore diffusion, with surface diffusion at the earlier stages followed by pore diffusion at the later stages. Analysis of adsorption data using a Boyd kinetic plot confirmed that external mass transfer is the rate determining step in the sorption process. A single-stage batch adsorber was designed for different CNS dose/effluent volume ratios using the Freundlich equation.

Desalination, 2011

The removal of Pb(II), Cu(II) and Cd(II) ions onto polyazomethineamides (PAMA) has been investiga... more The removal of Pb(II), Cu(II) and Cd(II) ions onto polyazomethineamides (PAMA) has been investigated using batch adsorption techniques. The extent of adsorption was investigated as a function of pH, adsorbent dose, contact time and initial metal ion concentration. The metal ion removal was pH-dependent and reached maximum at pH 6.0. Experimental data were analysed by Langmuir, Freundlich, Redlich-Peterson and Temkin adsorption isotherms. The characteristic parameters for each isotherms and related correlation coefficients have been determined using MATLAB 7.1. The maximum adsorption capacities of PAMA for Pb(II), Cu(II) and Cd(II) ions were calculated from the Langmuir isotherm 452.1, 470.7 and 462.3 mg/g respectively. Pseudo-first-order, pseudo-second-order, Elovich kinetic and intraparticle diffusion models were used to fit the experimental data. Kinetic parameters, rate constants, equilibrium sorption capacities and related correlation coefficients, for each kinetic model were calculated and discussed. The kinetic studies showed that the pseudo-second-order rate equation was better described by the adsorption process. The FT-IR spectra of the adsorbent indicated that the amide, amide carbonyl and azomethine groups were major binding sites with the metal ions. The adsorption of PAMA for heavy metal is selective, and the adsorption capacity is in the order of Cu(II) > Cd(II) > Pb(II).► Synthesis of new adsorbent, polyazomethineamides (PAMA). ► Removal of Pb(II), Cu(II) and Cd(II) ions using PAMA. ► Adsorption of heavy metal ions onto PAMA was pH dependent and optimum pH was 6.0. ► Adsorption capacity is in the order of Cu(II)>Cd(II)>Pb(II). ► Adsorption kinetics was followed by pseudo-second-order model.

Bioresource Technology, 2010

In this study free fatty acids present in Azadirachta indica (Neem) oil were esterified with our ... more In this study free fatty acids present in Azadirachta indica (Neem) oil were esterified with our synthesized phosphoric acid modified catalyst. During the esterification, the acid value was reduced from 24.4 to 1.8 mg KOH/g oil. Synthesized catalyst was characterized by NH3 TPD, XRD, SEM, FTIR and TGA analysis. During phosphoric acid modification hydrophobic character and weak acid sites of the mordenite were increased, which lead to better esterification when compared to H-mordenite. A kinetic study demonstrates that the esterification reaction followed pseudo-first order kinetics. Thermodynamic studies were also done based on the Arrhenius model.

Separation Science and Technology, 2012