CUTOFF PERFORMANCE OF ESCHERICHIA-COLI BY CHARGED AND NONCHARGED POLYACRYLONITRILE ULTRAFILTRATION MEMBRANES

Cutoff performance of Escherichia coli (E. coli) was studied by three types of polyacrylonitrile (PAN) ultrafiltration (UF) membranes withou t and with charge groups of sulfonate sodium salt (SSS) and trimethyla mmonium chloride (TMA). These UF membranes were prepared by phase inve rsion method in water coagulation bath with various concentrations of dimethylsulfoxide (DMSO) and used for the E. coli cutoff experiments u nder 2.5 kPa applied pressure. With the increase of the polymer concen tration in the DMSO cast solution, the pore size of the molecular size exclusion effect of the resultant UF membrane decreased. For UF exper iments of E. coli suspension solution with 10(7) colony forming unit/u nit volume (cfu/ml), the permeability of the bacteria through the memb rane was in the range of about 10(-3)% in PAN homopolymer membranes. I t was found that E. coli permeation through copolymer UF membranes wit h SSS and TMA groups was completely restricted. Difference of the E. c oli cutoff performance in these UF membranes was discussed in comparis on with membrane filtration properties such as molecular sieve effect, permeation rate of solute and membrane morphology. (C) 1998 Elsevier Science B.V.