title: Enzymatic esterification of ethanol by an immobilised Rhizomucor miehei lipase in a perforated rotating disc bioreactor.
abstract: A perforated rotating disc bioreactor was developed to perform the esterification of ethanol with oleic acid, catalyzed by a lipase from Rhizomucor miehei immobilized by adsorption on to a hydrophobic support-Accurel EP700. The bioreactor with total recirculation operated at an optimum agitation rate of 400 rev./min. The experimental results, in this condition, were predict by a kinetic model using the constants obtained in the batch (Erlenmeyer flasks) assays: a catalytic constant, k(cat) = 5.78 mmol/h. mg protein; a Michaelis constant for ethanol, K(m(Et)) = 1.20 M; a Michaelis constant for oleic acid, K(m(Ol)) = 1.16 x 10(-8) M, and a dissociation constant of the ethanol-lipase complex, K((Et)) = 9.46 x 10(7) M. The efficiency of conversion gradually decreased during continuous operation of the reactor. The enzymatic activity decayed according to a first order deactivation model and the integrated equations of a continuous stirred tank reactor (CSTR) and a plug flow reactor (PFR). A half-life time of the lipase of about 10 days and a deactivation constant of 0.003 h(-1) were obtained in the present system.
authors.affiliation: INETI-Departamento de Energias Renováveis, Estrada do Paço do Lumiar, 1649-038, Lisbon, Portugal
authors.initials: AC
authors.lastname: Oliveira
authors.initials: MF
authors.lastname: Rosa
authors.initials: MR
authors.lastname: Aires-Barros
authors.initials: JM
authors.lastname: Cabral