Vasanthakumar Sathyaselvabala

Synthesis of biodiesel from Neem oil using sulfated zirconia via tranesterification

Sulfated zirconia (SZ) is a widely used catalyst, which is synthesized by a solvent free method and the synthesized catalyst has been characterized. Neem Methyl Ester (Biodiesel) was prepared by a two-step process of esterification and transesterification from Neem oil with methanol in the presence of catalyst. Acid catalyst was used for the esterification and alkali catalyst (KOH) for the transesterification reaction. Optimal Free Fatty Acid (FFA) conversion was achieved using 1 wt% SZ as an acid catalyst with a methanol-to-oil molar ratio of 9:1, temperature of 65oC and reaction time of 2 h. The acid value was reduced to 94% of the raw oil (24.76 mg KOH/g), which confirmed the conversion. Consequently, this pretreatment reduces the overall complexity of the process and a conversion efficiency of 95% is achieved when pretreated oil reacts with methanol in the presence of KOH.

Removal of cadmium(II) from aqueous solution by agricultural waste cashew nut shell

Cashew nut shell (CNS) is a low cost adsorbent that has been used for the removal of cadmium(II) from an aqueous solution. The effects of various parameters such as solution pH, CNS concentration, contact time, initial cadmium(II) concentration and temperature were examined. The CNS was effective for the quantitative removal of cadmium(II) ions in acidic conditions and equilibrium was achieved in 30 min. The experimental data were analyzed by two-parameter (Langmuir, Freundlich, Temkin and Dubinin-Radushkevich) and three-parameter models (Redlich- Peterson, Koble-Corrigan, Toth and Sips) by nonlinear regression analysis. The characteristic parameters for each isotherms and related correlation coefficients have been determined by using MATLAB 7.1. Thermodynamic parameters such as ΔGo, ΔHo and ΔSo have also been evaluated, and it was found that the sorption process was feasible, spontaneous and exothermic. Pseudo-first-order, pseudo-second-order, Elovich kinetic and intraparticle diffusion models were selected to follow the adsorption process. The results of the kinetic study show that the adsorption of cadmium(II) could be described by the pseudo-second order equation, suggesting that the adsorption process is presumably chemisorption. A single-stage batch adsorber was designed for different adsorbent dose-to-effluent volume ratios using the Freundlich equation. The results indicate that the cashew nut shell could be used to effectively adsorb cadmium(II) from an aqueous solution.

Two-step biodiesel production from Calophyllum inophyllum oil: Optimization of modified β-zeolite catalyzed pre-treatment

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.

Removal of free fatty acid in Azadirachta indica (Neem) seed oil using phosphoric acid modified mordenite for biodiesel production

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 NH(3) 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.

Adsorption of methylene blue dye from aqueous solution by agricultural waste: Equilibrium, thermodynamics, kinetics, mechanism and process design

The adsorption of methylene blue (MB) dye from aqueous solution onto a cashew nut shell (CNS) was investigated as a function of parameters such as solution pH, CNS dose, contact time, initial MB dye concentration and temperature. The CNS was shown to be effective for the quantitative removal of MB dye, and the equilibrium was reached in 60 min. The experimental data were analysed by two-parameter isotherms (Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models) using nonlinear regression analysis. The characteristic parameters for each isotherm and the related correlation coefficients were determined. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were also evaluated, the sorption process was found to be spontaneous and exothermic. Pseudo-first-order, pseudo-second-order and Elovich kinetic models were used to analyze the adsorption process. The results of the kinetic study suggest that the adsorption of MB dye matches 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. Analysis of adsorption data using a Boyd kinetic plot confirmed that the external mass transfer is a rate determining step in the sorption process. A single-stage batch adsorber was designed for different CNS doses to effluent volume ratios using the Freundlich equation. The results indicated that the CNS could be used effectively to adsorb MB dye from aqueous solutions.

Application of Response Surface Methodology to Optimize Three Phase Partitioning for Purification of Laccase from Pleurotus ostreatus

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.

Kinetic and equilibrium studies on the biosorption of textile dyes onto Plantago ovata seeds

The powdered seeds of Plantago ovata (PSPO) were utilized for the removal of Malachite Green (MG) and Rose Bengal (RB) dyes from aqueous media by batch adsorption. The Fourier transform infra red spectroscopy (FTIR) results showed that both the dyes were adsorbed between the cellulose matrices, and this has been verified from the intensifying and narrowing aromatic C-H bending vibration. The morphology of the dye laden adsorbent was studied by scanning electron microscopy (SEM), which showed that the dyes were adsorbed between the cellulose matrices of the adsorbent. The PSPO was found to be very effective for the removal of MG and RB at pH 7, and equilibrium was attained within 200 min. The kinetic study indicated that the rate limiting step for MG and RB adsorption may be chemisorption and intraparticle diffusion. Adsorption equilibrium data were fitted to Langmuir, Freundlich, Redlich-Peterson and Temkin adsorption isotherms. It is inferred from the equilibrium studies that the adsorption of MG follows the Freundlich isotherm and the adsorption of RB follows the Langmuir isotherm. The maximum monolayer adsorption capacity of the PSPO was found to be 86.23 mg/g for MG and 81.23 mg/g for RB, respectively.