Comparative study of the properties of lipase immobilized on nonwoven fabric membranes by six methods

Nonwoven fabrics of polypropylene (PP), polyethylene terephthalate (PET) and viscose fiber were used as novel and inexpensive support membranes for the immobilization of lipase. The use of a co-solvent during the immobilization process improved the activity of the coupled protein and the operational stability of PP and PET membranes. Covalent methods of immobilization caused the support membranes to become fragile and the lipase was easily deactivated. A hydrophobic treatment improved the protein-coupled content of silk cotton, viscose and PET surfaces more than threefold. Viscose prepared with the hydrophobic treatment could be reused up to 44 times and retained a static water contact angle of 131.8°. The initial rate of esterification remained high even when the amount of added water was increased to 10%. In a model application reaction of oleic acid and ethanol with 8% (v/v) added water, the acid conversion rate of post-hydrophobic treated immobilized lipase improved by at least 10% in each of five batches. These results suggest that a hydrophobic surface results in a lower amount of adsorbed water on the support membrane and provides a more suitable microenvironment for the enzymes. Nonwoven viscose could be a potential enzyme immobilization matrix for industrial processes.