Background: Transesterification of Jatropha oil was carried out in t-butanol solvent using immobilized lipase from Enterobacter aerogenes. The presence of t-butanol significantly reduced the negative effects caused by both methanol and glycerol. The effects of various reaction parameters on transesterification of Jatropha oil were studied.

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A novel support has been utilized for immobilization of lipase, which was prepared by amination of silica with ethanolamine followed by cross linking with glutaraldehyde. Lipases from Rhizopus oryzae 3562 and Enterobacter aerogenes were immobilized on activated silica gel, where they retained 60 and 50% of respective original activity. The thermal stability of the immobilized lipases was significantly improved in comparison to the free forms while the pH stability remained unchanged. E. aerogenes and R. oryzae 3562 lipases retained 75 and 97% of respective initial activity on incubation at 90 degrees C, whereas both the free forms became inactive at this temperature. The conversion yield of isoamyl acetate was found to be higher with the immobilized fungal (90 vs. 21%) and bacterial lipases (64 vs. 18%) than the respective free forms. Immobilized R. oryzae 3562 lipases retained 50% activity for isoamyl acetate synthesis up to ten cycles whereas it was eight cycles for E. aerogenes.

The present article deals with the theoretical study on electrophoresis of hydrophobic and dielectric spherical fluid droplets possessing uniform surface charge density. Unlike the ideally polarizable liquid droplet bearing constant surface ζ-potential, the tangential component of the Maxwell stress is nonzero for dielectric fluid droplets with uniform surface charge density. We consider the continuity of the tangential component of total stress (sum of the hydrodynamic and Maxwell stresses) and jump in dielectric displacement along the droplet-to-electrolyte interface. The typical situation is considered here for which the interfacial tension of the fluid droplet is sufficiently high so that the droplet retains its spherical shape during its motion. The present theory can be applied to nanoemulsions, hydrophobic oil droplets, gas bubbles, droplets of immiscible liquid suspended in aqueous medium, etc. Based on weak field and low charge assumptions and neglecting the Marangoni effect, the resultant electrokinetic equations are solved using linear perturbation analysis to derive the closed form expression for electrophoretic mobility applicable for the entire range of Debye−Huckel parameter. We further deduced an alternate approximate expression for electrophoretic mobility without involving exponential integrals. Besides, we have derived analytical results for mobility pertaining to various limiting cases. The results are further illustrated to show the impact of pertinent parameters on the overall electrophoretic mobility.

Background: Immobilized lipase mediated tranesterification process for new feed stock Simarouba glauca oil for biodiesel production has been developed by utilizing the greener aspects of immobilized biocatalyst in n-hexane solvent system. The presence of solvent system helps to overcome the negative effects of methanol and glycerol, the end product. Effect of methanol to oil ratio, reaction time, methanol to hexane ratio, reaction temperature, agitation speed and immobilized lipase on final molar conversion were investigated. Results: A maximum yield of 91.5 % fatty acid methyl esters with a 62.23 % molar conversion with respect to methyl oleate has been achieved with oil: methanol molar ratio of 1:1, using 10 U of immobilized lipase/g of oil and with methanol to oil ratio of 1:0.6 in a reaction time of 36 h at 34°C and 200 rpm. Immobilized lipase has been reused successfully up to 6 recycles with retaining relative activity of more than 95 %. Conclusion: Lipase mediated tranesterification of new feedstock Simarouba glauca oil for biodiesel production has been successfully carried out under n-hexane solvent system. Utilization of immobilized lipase, which facilitates reuse helps considerably for the economy of the process. The introduced new feedstock with a green tinge seems to be a very promising to the biofuel sector for biodiesel production through sustainable approach.