Comparative study of the hydrolysis of different oils by lipase-immobilized membranes

Lipase immobilization on asymmetric polysulfone (PS) membranes was done by physical adsorption and covalent coupling techniques. The glutaraldehyde (Glu) crosslink showed maximum immobilization (1.53 mg/cm²) on the hydrazine (Hz)-modified membrane surface. Lipase immobilization on the membrane was proved by different analytical tools (viz., X-ray diffraction, scanning electron microscopy). The hydrolase-immobilized enzyme marked its hydrolyzing ability to different oils (olive, palm, and castor oils). The hydrolysis yield (U/mg) for the different immobilized membranes was in the following order: Olive oil > Palm oil > Castor oil. The PS–Hz–Glu–lipase membrane showed maximum hydrolyzing ability for olive oil (62.37 U/mg) and minimum hydrolyzing ability for castor oil (38.11 U/mg). The low aptitude for the hydrolysis of castor oil was explained by the presence of ricinoleic acid in the main composition. The lowest affinity toward castor oil (Michaelis–Menten constant = 18.86 mM) also featured the same. The order of maximum reaction rate for the same membrane was as follows: Olive oil (64.5) > Palm oil (62.5) > Castor oil (41.6). The immobilized lipase on PS–Hz–Glu suffered only a 12.5% deterioration for olive oil after five cycles. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012