1. Comparison of the esterification of fructose and palmitic acid in organic solvent and supercritical carbon dioxideSaša Šabeder, Maja Leitgeb, Željko Knez, 2005, original scientific article Abstract: Sugar fatty acid esters are nonionic surfactants, which are used for personal care products, cosmetic applications, and as emulsifiers for food. In recent years, enzymatic synthesis of sugar fatty acid esters is attracting keen attention as a new manufacturing method for future application. Reaction parameters of lipase-catalyzed synthesis of fructose fatty acid esters in organic solvent were optimized in a batch reactor at atmospheric pressure. Optimum conditions for reaction performed in organic solvent at atmospheric pressure were 10% (wžw of substrates) of lipase from Candida antarctica B, 12.14% (wžw of reaction mixture) of molecular sieves at 60 C, and stirring rate of 600 rpm. Esterification of fructose and palmitic acid was performed insupercritical carbon dioxide with and without addition of cosolvent (organicsolvent) at 60 C. Effect of pressure on enzyme activity was studied.
Keywords: chemical processing, high pressure technology, supercritical CO2, esterification, organic solvent, lipase catalysed synthesis, fructose fatty esters, Candida antarctica B, enzyme activity
Published in DKUM: 01.06.2012; Views: 2400; Downloads: 212
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2. Lipase-catalyzed transesterification of (R,S)-1-phenylethanol in SC $CO_2$ and in SC $CO_2$/ionic liquid systemsMuzafera Paljevac, Željko Knez, Maja Leitgeb, 2009, original scientific article Abstract: Commercial immobilized lipase B from Candida antarctica (CALB) was successfully applied to catalyzing the transesterification of (R,S)-1-phenylethanol in supercritical carbon dioxide and in supercritical carbon dioxide/ionic liquid biphasic system. Firstly, the variables affecting the performance of CALB in transesterification reactions in supercritical carbon dioxide, such as CALB concentration, temperature and pressure, were studied. An increase in the conversion and in the reaction rate was observed as the CALB/substrate ratio, temperature and pressure, were increased from 4.3 to 19.9, from 40 °C to 80 °C and from 8 MPa to 10 MPa, respectively. Further increase in temperature from 80 °C to 120 °C and pressure from 10 MPa to 30 MPa resulted in lower conversion and lower initial reaction rate. Furthermore, different vinyl esters were used as acyl donors for CALB-catalyzed transesterification of (R,S)-1-phenylethanol in supercritical carbon dioxide. The highest initial reaction rate was attained with vinyl butyrate, although 50% conversion was attained faster when vinyl acetate was used as acyl donor.
Secondly, in transesterification of (R,S)-1-phenylethanol, performed in supercritical carbon dioxide/ionic liquid biphasic system, influence of concentration of 1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF$_4$] was studied. The addition of 50 mmol (70% w/w reaction mixture) of [bmim][BF$_4$] to the reaction system gave the best result in terms of transesterification rate.
Keywords: candida antarctica lipase B, transesterification, (R, S)-1-phenylethanol, ionic liquids, vinyl acetate, supercritical carbon dioxide
Published in DKUM: 31.05.2012; Views: 2480; Downloads: 303
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3. The lipase-catalyzed synthesis of fatty acid fructose esters in organic media and in supercritical carbon dioxideSaša Šabeder, Maja Leitgeb, Željko Knez, 2006, original scientific article Abstract: Sugar fatty acid esters are biodegradable surface active compounds in foodstuffs and cosmetics or pharmaceuticals. They have potential in replacing pollutant chemically synthesized surfactants. The enzymatic synthesis of fructose palmitate catalyzed by Candida antarctica B lipase was performed in different organic media in a batch react at atmospheric pressure. The influence of the organic solvent and temperature on the esterification was studied. Since supercritical carbon dioxide (SC CO2) has several advantages over organic solvents, such as high reaction rate, high mass transfer, non-toxicity, non flammability and low price, it was also chosen as a reaction medium for fructose palmitate production. The influence of temperature on immobilized lipase activity was studied at 10 MPa and the results were compared to the results obtained from reactions performed at atmospheric pressure under the same reaction conditions. The highest conversion (67%) was obtained after 24 hours of reaction in SC C02 at 80°C. A change of the particle size distribution and morphology of the untreated lipase and lipase treated with 2-methyl 2-butanol and SC C02 was observed.
This article was presented at 1st SEECChE, held in Belgrade, September 25-28, 2005
Keywords: chemical processing, high pressure technology, supercritical CO2, lipase catalyzed syntheses, esterification, fructose palmitate, biocatalysts, lipase, Candida antarctica B
Published in DKUM: 31.05.2012; Views: 2712; Downloads: 536
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4. SINTEZA SAHAROZA PALMITATA V ORGANSKIH TOPILIHMaja Bahlen, 2011, undergraduate thesis Abstract: Namen diplomskega dela je bil sintetizirati saharozo palmitat, ki se uporablja v kozmetični, farmacevtski in prehrambeni industriji. Osredotočili smo se na sintezo saharoza palmitata v t-butanolu, vendar smo za primerjavo izvedli tudi sinteze v drugih organskih topilih, kot so etil metil keton, aceton in tert-amil alkohol. Encimsko katalizirano sintezo saharoza palmitata smo izvedli v mešalnem šaržnem reaktorju pri temperaturi 60 °C. Reakcijo smo katalizirali z imobilizirano lipazo B iz Candida antarctica. Produkt reakcije je bil saharoza mono-, di- in tri-palmitat. Reakcije smo izvedli z različnimi množinskimi razmerji substratov (palmitinska kislina : saharoza). Najvišjo presnovo smo dobili v primeru, ko je bilo množinsko razmerje substratov (palmitinska kislina : saharoza) 10 : 90.
Keywords: encimsko katalizirana sinteza, lipaza B iz Candida antarctica, saharoza palmitat, organska topila, t-butanol
Published in DKUM: 04.10.2011; Views: 4303; Downloads: 257
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