Immobilized lipases biodiesel produced using

A membrane cell recycle reactor with continuous ethanol extraction by dibutyl phthalate increased the productivity fourfold with increased conversion of glucose from 45 to 91%.249 The ethanol was then removed from the dibutyl phthalate with water. It would be better to do this second step with a membrane. In another process, microencapsulated yeast converted glucose to ethanol, which was removed by an oleic acid phase containing a lipase that formed ethyl oleate.250 This could be used as biodiesel fuel. Continuous ultrafiltration has been used to separate the propionic acid produced from glycerol by a Propionibacterium.251 Whey proteins have been hydrolyzed enzymatically and continuously in an ultrafiltration reactor, with improved yields, productivity, and elimination of peptide coproducts.252 Continuous hydrolysis of a starch slurry has been carried out with a-amylase immobilized in a hollow fiber reactor.253 Oils have been hydrolyzed by a lipase immobilized on an aromatic polyamide ultrafiltration membrane with continuous separation of one product through the membrane to shift the equilibrium toward the desired products.254 Such a process could supplant the current energy-intensive industrial one that takes 3-24 h at 150-260X. Lipases have also been used to prepare esters. A lipase-surfactant complex in hexane was used to prepare a wax ester found in whale oil, by the esterification of 1 hexadecanol with palmitic acid in a membrane reactor.255 After 1 h, the yield was 96%. The current industrial process runs at 250°C for up to 20 h. 

Although immobilization can reduce the overall production cost, the overall cost is still much higher than that of chemical-catalyzed processes. Jegannathan et al. (2011) determined the economic feasibility of producing 1000 tons of biodiesel from palm oil using alkali and lipase catalysts in both soluble and immobilized forms. The alkali-catalyzed process cost was found to be lowest followed by the immobilized form of the lipase. However, in this research it was assumed that lipase could be reused only five times. If reusability is increased, the lipase processes becomes more feasible. 

Arumugam, A., Ponnusami, V., 2014. Biodiesel production from CalophyUum inophyllum oil using lipase producing rhizopus oryzae cells immobilized within reticulated foams. Renewable Energy 64, 276—282. 

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