Kinetics of Enzyme-Catalyzed Alcoholysis of Soybean Oil in n-Hexane

The role of organic solvent amount in the lipase-catalyzed biodiesel production

“…The fatty acid composition used in this work (OlIVEIRA et al, 2005a) is very similar to the typical values reported in the literature (SRIVASTAVA; PRASAD, 2000; AlTIN; ÇETINKAYA; YUCESU, 2001). Ethyl alcohol and n-hexane (both from merck, 99.9% pure) were used as substrate and solvent, respectively.…”

“…This specific result obtained for both enzymes with 30 ml of solvent will not be overemphasized, as it does not bring new information nor is it the focus of the present work; i.e., differences found between the performance of Novozym 435 compared to lipozyme Im are not stressed as they may be considered a "classical result" available in the open literature (OlIVEIRA et al, 2005a;VICENTE et al, 1998). Perhaps, the poorer performance verified for Novozym 435, compared to lipozyme Im, may be related to substrate inhibition (alcohol and/or oil), solvent denaturing caused by deleterious interaction between the enzyme-solvent.…”

“…In order to investigate the effect of solvent amount in the enzymatic biodiesel production, the experimental conditions adopted were those found in the work of Oliveira et al (2005a). Figure 1 shows the experimental results for lipozyme Im, which exhibits specificity in the 1.3 triglyceride positions, and Novozym 435, a non-specific lipase,for 6 hours reaction.…”

“…Though at present the high cost of enzyme production is the major obstacle to commercializing enzyme-catalyzed processes, advances in enzyme technology, such as the use of solvent-tolerant lipases and immobilized lipases, which enable the catalyst re-utilization, have been made to develop cost-effective systems (FUKUDA; KONDO;NODA, 2001;ISO et al, 2003). In this sense, several research studies have reported an alternative method to produce esters through enzymatic reactions using lipases as catalysts, the majority of them using organic liquid solvents as reaction medium (YAmANE, 1988;ABRAmOWICZ;KUSE, 1989;BARZANA;KAREl;KlIBANOV, 1989;YAmANE et al, 1990;STEVENSON;STORER, 1991;CARTA;GAINER;ZAIDI, 1995;AlVES, 1999AlVES, , 2000OlIVEIRA et al, 2004OlIVEIRA et al, , 2005a. many lipase-catalyzed reactions have been performed in compressed fluids (mostly carbon dioxide) in an attempt to…”

“…concentration (E, wt%) = 5, oil to ethanol molar ratio (R) = 1:10, water addition (H, wt%) = 0, and for lipozyme Im -35 o C, E = 5 wt%, R = 1:3, H = 10 wt% (OlIVEIRA et al, 2005a), 1 g of oil was used in the experiments and n-hexane was used as solvent medium, varying its amount from zero to 50 ml.…”