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- Candida antarctica lipase A (2)
- Ester oil (2)
- 2-Ethyl-1-hexyl palmitic acid ester (1)
- Adsorption (1)
- Arc furnace (1)
- Beugung (1)
- Biodiesel (1)
- By-product (1)
- Chrom (1)
- Chromium recovery (1)
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)].
Für die Entfernung von VOC (volatile organic compounds) aus der Luft von Fertigungsstätten werden vielfach mikroporöse Adsorbentien eingesetzt. Die gereinigte Luft wird rezyklisiert. Für die mit VOC beladenen Adsorbentien wird ein Regenerierungsweg für den mehrfachen Gebrauch gesucht. Bei der Regenerierung sollen die VOC möglichst vollständig desorbiert werden und mit einer geringen Gasmenge in einer katalytischen Verbrennung zu CO2 und H2O umgewandelt werden. Die Wirtschaftlichkeit der Luftreinigung wird wesentlich bestimmt durch die Sorptionskapazität des Adsorbens, die erforderliche Energie für die thermische Regenerierung und die Menge des Spülgases bei der Regenerierung. In dieser Arbeit wird der Einsatz von Typ X-Zeolithpulver in der Luftreinigung einer Lackiererei beschrieben und dessen Regenerierung im Labor mittels DTA/TG und Isothermenmessung der Schlüsselkomponenten untersucht. Ferner wurde die Regenerierung des beladenen Zeoliths in einem Labor-Drehrohrofen unter Variation der Betriebsparameter untersucht und anschließend mit ausgewählten Parametern in einem kleintechnischen Drehrohrofen durchgeführt. Die Verfahrensvarianten werden diskutiert.
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.
Für die vollständige Rückgewinnung des in Edelstahlschlacken enthaltenen Chroms wird eine reduzierende Schmelzbehandlung im Elektro-Lichtbogenofen vorgeschlagen. Dabei wird das in der Schlacke enthaltene Cr2O3 zum Metall reduziert und in der schmelzflüssigen Phase separiert. Die Effektivität der Reduktion wird entscheidend durch die Fahrweise des Lichtbogenofens bestimmt. Mit optimalen Bedingungen lassen sich mehr als 90 % des enthaltenen Chroms als metallische Legierung zurückgewinnen
Slags from the production of high-alloyed steel contain both chemically bound chromium (mainly as Cr2O3) in the mineral fraction and elemental chromium in the metallic remainders. Thermochemical post treatment of the slag in an electric arc furnace under reducing conditions enables the nearly complete recovery of the total amount of chromium in form of a metallic alloy. The best results were achieved by resistance melting (submerged electrodes) with addition of a reducing agent into the melt. The efficiencies of the reducing agents carbon, aluminium, silicon (as ferrosilicon) and silicon carbide were investigated and compared. As aluminium is the strongest reducing agent, it is less selective and reduces much more SiO2 than Cr2O3. While SiC shows only low reactivity because of its high thermal resistance, carbon and silicon had the highest reducing potentials: More than 97% of the chemically bound chromium can be recovered by application of these reducing agents. Due to the high temperature required for the reduction of the chromium compounds, the reduction of SiO2 as an undesired side reaction cannot be avoided. However, compared with mechanical procedures that are limited to the recovery of the metallic remainders, the total chromium recovery can be significantly increased by the described reductive melting procedure.