Poly(L-lactic acid) Microfiltration Membrane Formation via Thermally Induced Phase Separation with Drying

概要

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Microfiltration membranes of poly(L-lactic acid) (PLLA), which is one of the major biodegradable plastics, were prepared from PLLA-1,4-dioxane-water solutions via the thermally induced phase separation. The resulting membranes are used to retain bacterial cells and permeate protein molecules. Only 20% bacterial cells in cell suspensions were retained by the membranes prepared from 10-12.5% polymer solution. By increasing the polymer concentration from 12.5 to 15% markedly elevated the bacterial cell retention to 60%. The retention further increased to 90% by elevating the casting temperature from 40 to 50°C. By drying the polymer solution for 2 min before quenching the cell retention reached 99%. Casting at temperatures of 60°C or higher and the drying for periods of 5 min or longer made the membrane uneven and/or increased the membrane resistance. By drying the polymer solution before quenching, the porous structure near the membrane surface was altered so that the membrane retains the bacterial cells. The membrane retained bacterial cells in a manner of screen filters. The membranes developed in this research will be useful as a pre-filter in biochemical processes to enhance the life time of the final filters and to reduce industrial wastes because it is made of a compostable polymer.
2011-07-01