Sahadevan Renganathan

Optimization and kinetic studies on algal oil extraction from marine macroalgae Ulva lactuca

In this present investigation, kinetic studies on oil extraction were performed in marine macroalgae Ulva lactuca. The algal biomass was characterized by scanning electron microscopy and Fourier Transform-Infra Red Spectroscopy. Six different pre-treatment methods were carried out to evaluate the best method for maximum oil extraction. Optimization of extraction parameters were performed and high oil yield was obtained at 5% moisture content, 0.12 mm particle size, 500 rpm stirrer speed, 55°C temperature, 140 min time and solvent-to-solid ratio as 6:1 with 1% diethyl-ether and 10% methylene chloride in n-hexane solvent mixture. After optimization, 10.88% (g/g) of oil extraction yield was achieved from 30 g of algal biomass. The rate constant was obtained for the first order kinetic study by differential method. The activation energy (Ea) was calculated as 63.031 kJ/mol. From the results obtained in the investigation, U. lactuca biomass was proved to be a suitable source for the biodiesel production.

Production of algal biodiesel from marine macroalgae Enteromorpha compressa by two step process: Optimization and kinetic study

In this investigation, Enteromorpha compressa algal oil with high free fatty acids (FFA) used as a feedstock for biodiesel production. Two step process was developed and kinetic study executed to obtain reaction rate constant for the transesterification reaction. The acid esterification was carried out to reduce FFA from 6.3% to 0.34% with optimized parameters of 1.5% H(2)SO(4), 12:1 methanol-oil ratio, 400 rpm at 60 °C and 90 min of reaction time. The maximum biodiesel yield 90.6% was achieved from base transesterification through optimum conditions of 1% NaOH, 9:1 methanol-oil ratio, 600 rpm and 60 °C temperature for 70 min. The algal biodiesel was characterized by GC-MS, HPLC and NIR. This transesterification follows first order reaction kinetics and the activation energy was determined as 73,154.89 J/mol. The biodiesel properties were analyzed and found to be within the limits of American standards. Hence, E. compressa serves as a valuable renewable raw-material for biodiesel production.

Production of biodiesel from mixed waste vegetable oil using an aluminium hydrogen sulphate as a heterogeneous acid catalyst.

Al(HSO(4))(3) heterogeneous acid catalyst was prepared by the sulfonation of anhydrous AlCl(3). This catalyst was employed to catalyze transesterification reaction to synthesis methyl ester when a mixed waste vegetable oil was used as feedstock. The physical and chemical properties of aluminum hydrogen sulphate catalyst were characterized by scanning electron microscopy (SEM) measurements, energy dispersive X-ray (EDAX) analysis and titration method. The maximum conversion of triglyceride was achieved as 81 wt.% with 50 min reaction time at 220°C, 16:1 molar ratio of methanol to oil and 0.5 wt.% of catalyst. The high catalytic activity and stability of this catalyst was related to its high acid site density (-OH, Brönsted acid sites), hydrophobicity that prevented the hydration of -OH group, hydrophilic functional groups (-SO(3)H) that gave improved accessibility of methanol to the triglyceride. The fuel properties of methyl ester were analyzed. The fuel properties were found to be observed within the limits of ASTM D6751.

Ultrasound-enhanced rapid in situ transesterification of marine macroalgae Enteromorpha compressa for biodiesel production.

In situ transesterification of Enteromorpha compressa algal biomass was carried out for the production of biodiesel. The maximum methyl esters (ME) yield of 98.89% was obtained using ultrasonic irradiation. Tetra hydro furan (THF) and acid catalyst (H2SO4) was found to be an appropriate co-solvent and catalyst for high free fatty acids (FFA) content E. compressa biomass to increase the efficiency of the reactive in situ process. The optimization study was conducted to obtain the maximum yield and it was determined as 30vol% of THF as a co-solvent, 10wt% of H2SO4, 5.5:1 ratio of methanol to algal biomass and 600rpm of mixing intensity at 65°C for 90min of ultrasonic irradiation time. The produced biodiesel was characterized by (1)H nuclear magnetic resonance spectroscopy ((1)H NMR) analysis. Kinetic studies revealed that the reaction followed the first-order reaction mechanism. Rapid in situ transesterification was found to be suitable technique to produce biodiesel from marine macroalgae feedstock.

Accumulation of Methylene Blue Dye by Growing Lemna minor

In the present investigation bioaccumulation studies were performed for the removal of Methylene Blue dye from an aqueous solution using live Lemna minor. The effect of various parameters such as the biosorbent dosage (1–3 g), pH (3-8) and initial dye concentration (2–10 mg L−1) were studied. The maximum uptake capacity of the Methylene Blue using L. minor was observed as 10.93 mg g−1 at a biosorbent dosage of 1 g/300 mL, at pH 7 and at 10 mg L−1 initial dye concentration. The surface morphology was analyzed using Scanning Electron Micrograph (SEM) for analyzing micro and macropores present on the surface of the plant and the functional groups on the biosorbent were analyzed using Fourier transform infrared analyzer (FTIR) for increasing the electrostatic attraction between the plant surface and the dye molecules by adjusting the pH of the solution. Equilibrium data was analyzed using Langmuir and Freundlich adsorption isotherm models. The Freundlich adsorption isotherm was found to be fitted well. The effect of initial dye concentration on the growth of the plant was studied by obtaining the growth profile of the plant on the basis of the relative growth rate (RGR).

Production of L-Asparaginase from Natural Substrates by Aspergillus terreus MTCC 1782: Effect of Substrate, Supplementary Nitrogen Source and L-Asparagine

In the present work, the fungal species Aspergillus terreus MTCC 1782 was used for the production of L-asparaginase using natural substrates like groundnut oil cake, cottonseed oil cake and corn flour in modified Czepak-Dox media and compared the L-asparaginase production using synthetic L-proline. The modified Czepak-Dox media with 2% L-proline, supplemented with 1% sodium nitrate and 1% L-asparagine has shown maximum L-asparaginase activity of 34.98 IU/mL on the third day of production. The modified Czepak-Dox media with 2% groundnut oil cake, 1% sodium nitrate and 1.2% L-asparagine showed maximum L-asparaginase activity of 30.35 IU/mL on the fourth day. These results are comparatively higher than the maximum L-asparaginase production reported in the literature (19.5 U/mL), by isolated Aspergillus sp. using Czepak-Dox media containing 2% (w/v) L-asparagine as the sole substrate along with 1% (w/v) ammonium sulfate as an additional nitrogen source. It is observed that the addition of L-proline or ground nut oil cake increases the L-asparaginase production. The groundnut oil cake is found as the potential natural and cheaper substrate for L-asparaginase production by Aspergillus terreus MTCC1782.

Hydrothermal liquefaction of freshwater and marine algal biomass: A novel approach to produce distillate fuel fractions through blending and co-processing of biocrude with petrocrude

Biocrude was produced from Tetraselmis sp. - a marine alga and Arthrospira platensis - a fresh water alga using hydrothermal liquefaction (HTL) process. Considering the constraints in cultivating algae for replacing 100% petrocrude, this study evaluated the option of blending and co-processing algal biocrude with petrocrude. Biocrudes obtained from algal strains cultivated in fresh water and sea water were blended with petrocrude at 10% concentration and the characteristics were studied using FT-IR and CNS SIMDIST. True Boiling Point (TBP) distillation was carried out to assess yields and properties of distillates of blended biocrudes. Biocrudes obtained from both algae were light crudes and the blended crudes recorded distillate yields of 76-77 wt%. The yield of light naphtha fraction of biocrude blends was 29-30%; whereas the yield of diesel fraction was about 18%. This study proposes blending and co-processing of algal biocrude with petrocrude to produce drop-in biofuels.

An Eco-Friendly Catalyst Derived From Waste Shell Of Scylla Tranquebarica For Biodiesel Production

The present investigation involves the production of environmental-friendly heterogeneous catalyst from waste Scylla tranquebarica crab shell and optimization of process parameter for biodiesel production from sunflower oil. A complete characterization of the catalyst including catalytic transesterification reaction was studied using gas chromatogram (GC), thermal gravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and 1H nuclear magnetic resonance (1H NMR). An optimum conversion of 94.2% was achieved at 95°C; methanol--oil molar ratio 12:1; 8 wt % catalyst in 75 min. It was found that the catalytic activity has the ability to compete with the other conventional heterogeneous catalysts. This study includes optimal conditions for the removal of the leached catalyst in biodiesel to enhance product purity. This reaction follows a first-order reaction kinetics. The rate constant and activation energy were determined. Fuel properties of biodiesel produced were determined and compared with ASTM standards.

Statistical and evolutionary optimisation of operating conditions for enhanced production of fungal l-asparaginase

A three-level central composite design of the Response Surface Methodology and the Artificial Neural Network-linked Genetic Algorithm were applied to find the optimum operating conditions for enhanced production of l-asparaginase by the submerged fermentation of Aspergillus terreus MTCC 1782. The various effects of the operating conditions, including temperature, pH, inoculum concentration, agitation rate, and fermentation time on the experimental production of l-asparaginase, were fitted to a second-order polynomial model and non-linear models using Response Surface Methodology and the Artificial Neural Network, respectively. The Artificial Neural Network model fitted well, achieving a higher coefficient of determination (R2 = 0.999) than the second-order polynomial model (R2 = 0.962). The l-asparaginase activity (38.57 IU s mL−1) predicted under the optimum conditions of 32.08°C, pH of 5.85, inoculum concentration of 1 vol. %, agitation rate of 123.5 min−1, and fermentation time of 55.1 h was obtained using the Artificial Neural Networklinked Genetic Algorithm in very close agreement with the activity of 37.84 IU mL−1 achieved in confirmation experiments.

Studies on a Customized Carbon Catalyst in Biodiesel Production from Waste Sunflower Oil

In this study, transesterification of waste sunflower oil with high free fatty acid was studied in a combined heterogeneous and homogeneous catalytic system. Production of hetero-carbon catalyst and their characteristics were done. The effects of the heterogeneous carbon on the homogeneous acid and base catalyzed transesterification reaction were analyzed. Parameters, such as reaction temperature, reaction time, and excess methanol, affecting the reaction were optimized to obtain a high yield of biodiesel. The results clearly showed that the introduction of customized carbon reduced both acid and base catalyst consumption. It was observed that carbon alone is not responsible for catalyzing the transesterification reaction but the addition of carbon reduces the homogeneous catalyst consumption. It was found that the catalytic activity of carbon with acid catalyst was found to have maximum performance. The highest conversion of waste sunflower oil was found to be 82% with acid catalyst at the following optimized process conditions: Combination of 1.5 wt% H2SO4, 5 wt% carbon, 90 minutes reaction time at 65°C, and 100% excess methanol.