Formation of depth filter microfiltration membranes of poly(l-lactic acid) via phase separation

Preparation of poly(L-lactic acid) microfiltration membranes by a nonsolvent-induced phase separation method with the aid of surfactants

“…The membrane prepared with these conditions had low permeation resistance (high water permeability) and high retention in the filtration of bacterial cell suspensions. The resistance of the PLLA membrane (1 Â 10 11 m -1 ) was comparable with those of the membrane developed for the retention of bacterial cells before (0.6-2 Â 10 11 m -1 ) [8,9]. However, the membrane preparation method at 25 1C in this study was easily compared with the methods with high temperature, quenching, and/or partial drying of polymer solutions.…”

“…1). Formation of finger-like structures in a PLLA membrane has been reported from a polymer solution in dimethylsulfoxide in nonsolvent and thermally induced phase separation elsewhere [9,22].…”

“…A filtration cell (Amicon model 8010, 4.1 cm 2 , Millipore, Bedford, MA) was used without its stirrer for dead-end filtration experiments as reported elsewhere [9]. Water was used to measure the permeation resistance of the membranes.…”

“…The viscosity of water at 2572 1C was 0.89 mPa s [14]. Microbial cell suspensions of Lactobacillus plantarum NBRC15891T (0.7φ Â 2.5 μm) were used to examine the retention of bacterial cells by the membranes as reported elsewhere [9]. The bacterium was cultured statistically in a modified MRS medium [15] where fish extract was substituted for meat extract.…”

“…Dimethyl sulfoxide was used to dissolve 10 wt% PLLA at temperatures of 60 1C and higher; however, the polymer solution did not form a membrane but instead formed PLLA particles via the thermally phase separation method. By using a combination of thermally and nonsolvent induced phase separations methods with a polymer solution at 80 1C and a coagulation water bath at 25 1C, PLLA membranes that retained bacterial cells were prepared [9].…”