Immobilization of laccase from Pleurotus sajor-caju in polyamide membranes

Polyamide 6.6 (PA 6.6) membranes were modified with glutaraldehyde, in a phase inversion process. Immobilization of the enzyme laccase from Pleurotus sajor-caju in the modified PA 6.6 film was quantified in the presence of the reducer 2,2’-azino-bis-3-ethylbenzoazoline-6-sulfonate (ABTS). Under these conditions, phenolic compounds present in the ABTS were degraded by an oxidative process. In the case of the immobilized enzyme, was degraded after 6 h of reactions, while the same amount of ABTS was degraded after 1 h in the case of the free enzyme, since the oxidation process is decreased by the low diffusion of ABTS through the membrane containing the immobilized enzyme. This characteristic is relevant since the reaction kinetics may be controlled in immobilized systems. The kinetics of the thermal inactivation (kd) of laccase activity and the half-life (t1/2) were determined. It was found that there is the possibility for the enzyme to be reused. The process described may be useful for the treatment of textile effluents.

a b The low values obtained for ABTS oxidation at 2 h and 4 h may be due to the action of non immobilized laccases retained in the polymer which were liberated after 4 h.