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  • Enzymatic hydrolysis of sunflower oil in SC CO2
    Leitgeb, Maja ; Primožič, Mateja, 1975- ; Knez, Željko
    Enzyme was combined with SCF to use the benefits from both: enzyme (higher reaction rates, better product purity, safer process, etc.) and SCF (higher reaction rates, better transport properties, ... etc.). Hydrolysis of sunf1ower oil in SC CO2, was catalyzed by the native lipase from Aspergillus niger. The reaction was performed in a high-pressure batch-stirred-tank reactor. Thermal stability of the lipase was studied in SC C()2 at 300 bar. The temperature optimum was determined to be at 50°C. With further temperature increase a rapid lipase deactivation was observed. Because hydrolysis could be performed only in the presence of higher water concentrations, and enzymatic activity issensitive to the pH of the bulk solution, pH dependence of the hydrolysis inSC CO2 was studied. From Arrhenius diagram activation energy Ea (32.678 kJ/mol) was determined. Other thermodynamic properties like free energy change, Gibb's energy, enthalpy and entropy of formation were ca1culated, as well. The hydrolysis of sunf1ower oil was al so performed in high-pressure flat-shape membrane reactor. The biocatalyst was retained in the reactor by polymeric membranes. In the high-pressure membrane reactor one can avoid the negative effect of depressurization steps on enzyme activity, which are necessary in the high-pressure batch reactor if the biocatalyst should be reused. Therefore in the membrane reactor biocatalyst might be used for a long-term operation. When nylon membranes were used in the reactor for long-term hydrolysis performance at 100 bar and 50°C, the conversion was kept constant for at least 15 h.
    Vir: Proceedings of the 6th International Symposium on supercritical fluids, 28-29-30 April, 2003, Versailles (France). Tome 2. SCF Properties Reactions (Str. 1429-1434)
    Vrsta gradiva - prispevek na konferenci
    Leto - 2003
    Jezik - angleški
    COBISS.SI-ID - 7899414

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