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- Candida antarctica lipase A (2)
- Ester oil (2)
- Thermochemical treatment (2)
- 2-Ethyl-1-hexyl palmitic acid ester (1)
- Arc furnace (1)
- Beugung (1)
- Biodiesel (1)
- By-product (1)
- Chromium recovery (1)
- Dekontaminierung (1)
Ester oils obtained from natural long-chain fatty acids and alcohols are versatile substitutes for many petroleum-based products. Their efficient synthesis with the solvent-free esterification of free fatty acids (FFA) from by-products of biodiesel fabrication and 2-ethyl-1-hexanol with immobilised lipase from Thermomyces lanuginosa was investigated. The immobilisation of the biocatalyst in static emulsion yielded a specific esterification activity that was higher by a factor of 4.9-9.4 than the activity of the native enzyme. Favourable properties of the silicone-based immobilisation matrix in terms of stability and immobilisation yield were observed. In biodiesel by-products, the immobilised lipase catalysed the esterification of FFA as well as the transesterification of residual fatty acid methyl esters (FAME) to the desired ester oils. A conversion of 90% FFA and 35% FAME gave a total yield of 60%. The inactivation coefficients during repeated use in a stirred-tank reactor with intermittent pressure reduction were exceptionally low.
Zn-K transmission EXAFS measurements were performed on vitrified ashes from municipal waste incinerator facilities, which contain low amounts of Zn (up to 3 wt%) and sulphur (up to 0.5 wt%) in a ZnS phase. From the Fourier transform it can be concluded that the zinc ions are fourfold co-ordinated by oxygen or sulphur ions. The amount of zinc ions of sulphur environment, e.g. the concentration of ZnS, was determined by Fourier filtering and subsequent parameter fitting. A quantitative analysis of low ZnS concentrations up to 1 wt% has been performed for samples with a molar ratio Zn/S < 5.
Commercial native lipase A from Candida antarctica was used to produce alkyl esters through the alcoholysis of (waste) fats with 2-ethyl-1-hexanol. The process was carried out in batch stirred tank reactors (from 100 mL up to 3000 L).
The content of alkyl esters in reaction mixtures was determined by gradient HPLC using an evaporative light scattering detector and the reaction progress was controlled by determining the ratio of the palmitic acid ester peak area to the oleic acid ester peak area in HPLC chromatograms.
The results show that alcoholysis is the favoured reaction in presence of excess water and water-insoluble alcohols in comparison with hydrolysis (fatty acid content <5%). The optimum amount of water for the alcoholysis was found to be 80-100% of the amount of fat. In the presence of low quantities of water both alcoholysis and hydrolysis are slow.
Conversion rate increases with increasing temperature to 65-70 °C.
Based on these results a large-scale test to produce 3000 L of alkyl ester (to be used as lubricant coolant) was carried out. The experiments have proved that alcoholysis is completed after about 7-10 h depending on temperature.
The feasibility of using native lipase A from Candida antarctica (CAL-A) to esterify fatty acids with water-insoluble alcohols in the presence of excess water was investigated in stirred-tank reactors. For high reaction rates, a ratio of water:substrates of 0.61.4:1 (v/v) was required. CAL-A showed higher substrate selectivity for the esterification of saturated palmitic acid with branched-chain 2-ethyl-1-hexanol than for unsaturated oleic acid with linear alcohol (1-decanol). After 18 h at 70 °C in a 1.5 l bulk stirredtank reactor, an 2-ethyl-1-hexyl palmitic acid ester was obtained near 100 % yield [molar ratio palmitic acid:2-ethyl-1-hexanol ~1:1.25, with 1.11 % (w/w) Novocor ADL (based on palmitic acid weight)].