PERFORMANCE OF A BIPHASIC ORGANIC AQUEOUS HOLLOW-FIBER REACTOR USING IMMOBILIZED LIPASE

A biphasic organic/aqueous membrane bioreactor, which combined chemica l reaction with continuous extraction of product in the aqueous phase, was investigated. Lipase from Candida cylindracea was used as catalys t with the hydrolysis of triglycerides, to fatty acids and glycerol, a s a model-system for studying the optimal operating conditions. Asymme tric capillary membranes, made of polyamide, were used as support for the enzyme, which was immobilized into the sponge layer of the membran e by cross-how filtration. The catalytic behaviour of lipase, both imm obilized in a hydrophylic membrane and free in solution, was compared. The effects of pH, temperature and substrate concentration on reactor performance were studied. The catalytic stability of the immobilized enzyme was improved compared with the enzyme in solution. The immobili zed lipase showed no deactivation in an operating period of 16 days wh ereas lipase in solution gave an 80% decrease in specific activity aft er 2 days of continuous operation. The specific activity of immobilize d lipase was significantly influenced by the amount of enzyme loaded i nto the membranes. The optimal range of immobilized protein was betwee n 2 and 12 mg cm(-3). The positive results obtained with the model-sys tem were also confirmed using the biphasic organic/aqueous membrane bi oreactor in a potential practical application, namely the conversion a nd separation of one enantiomer from an organic racemic mixture of an ester.