Biocatalysis using lipase immobilised in organogels in supercritical carbon dioxide
The catalytic ability of lipases encapsulated in organogels with supercritical carbon dioxide as external solvent was studied. Lipase from Candida antarctica was encapsulated in lecithin water-in-oil microemulsion-based organogels (MBGs) formulated with hydroxypropylmethyl cellulose (HPMC). The este...
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| Format: | Thesis |
| Language: | English |
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2006
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| Online Access: | https://epub.uni-regensburg.de/10431/ https://epub.uni-regensburg.de/10431/1/Dissertation_Blattner.pdf |
| Summary: | The catalytic ability of lipases encapsulated in organogels with supercritical carbon dioxide as external solvent was studied. Lipase from Candida antarctica was encapsulated in lecithin water-in-oil microemulsion-based organogels (MBGs) formulated with hydroxypropylmethyl cellulose (HPMC). The esterification of lauric acid and 1-propanol catalysed by these MBGs was examined in supercritical carbon dioxide (35 °C, 110 bar) as solvent for the substrates. The effect of various parameters such as pressure, mass fraction of biopolymer, alcohol and carboxylic acid chain length was studied in supercritical carbon dioxide. Results are discussed with reference to experiments performed with isooctane as external solvent. In addition, a kinetic study of MBG-encapsulated C. antarctica showed that the ester synthesis catalysed by the immobilised lipase occurs via a Ping Pong Bi Bi mechanism in which only inhibition by excess of alcohol was identified. Initial experiments concerning the reusability of these gels, moreover, showed that the slight decrease of activity in supercritical carbon dioxide is similar to that observed in isooctane. In addition, the catalytic activity of HPMC MBGs containing C. antarctica lipase immobilised in so-called detergentless microemulsions comprised of n-hexane, 1-propanol, and buffer solution was investigated in supercritical carbon dioxide. It could be shown that this type of MBG is likewise active in supercritical carbon dioxide. Biocatalyst reuse experiments indicated that detergentless MBGs exhibit a better operational and storage stability than organogels formulated with classical microemulsions. Phytantriol-based organogels as a new type of immobilisation matrix were tested for their potential application as solid-phase catalysts with both isooctane and supercritical carbon dioxide as external solvents. It was shown that Mucor miehei lipase immobilised in such organogels is capable of catalysing the esterification of 1-propanol and lauric acid in both solvents. In order to determine the ... |
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