Study on Immobilization of Alkaline Lipase Used in Papermaking

In order to achieve the reuse of alkaline lipase in papermaking process,the alkaline lipase was immobilized on modified chitosan beads,and the enzymatic properties of immobilized lipase were examined.The results showed that the enzymatic activity,protein content and specific activity of the immobilized lipase could reach 64.6 U/g,253.7 μg/g and 254.6 U/mg respectively,when lipase was first immobilized to the hydroxyl groups of chitosan by activation with EDC followed by the immobilization of more lipase molecules through its amino groups by cross-linking with glutaraldehyde.Moreover after the binary immobilization,the optimum reaction temperature of the lipase increased from 50 to 55℃,and the optimum pH value changed from 7.5 to 8.5,compared with the free lipase.The operation stability of the lipase was also improved significantly,lipase immobilized by the binary method could retain 70% residual activity after reusing for five times.Therefore,the immobilized lipase can be reused to remove the pitch deposits in white water in alkaline papermaking.