Filtration and permeation characteristics of bacterial cellulose composite.

Abstract

The laminated or composite bacterial cellulose (BC) membrane is very useful not only for ultrafiltration but also for evapomeation of membrane separation techniques. BC membranes laminated with β-chitin or deacetylated chitin sulfonate (S-DAC) show high solute rejection, 85% rejection in the former, 90% rejection in the latter for PEG 50000 as compared with 30% rejection of normal BC membrane. They are twice level of the BC derivatives of acetate or nitrate. In particular the membrane thinly laminated with S-DAC is very effective for the separation of solute more than 50000 in molecular weight, and shows relatively high flux rate of 10-12L/m2h, and great strength. Water-soluble polymers such as hyroxyethyl cellulose (HEC), hydroxypropyl (HPC), carboxymethyl cellulose (CMC), methyl cellulose (MC) and carboxymethyl chitin (CM-chitin), have been incorporated into BC during incubation as high as 30wt%. The water-soluble polymers influence more or less their preferential orientation. CMC and CM-chitin additives provide the highest transparency index of 2 or 3 times as compared with normal BC. The composite membranes with HEC and CM-chitin are good UF membrane which show very sharp slope and the highest rejection of more than 95% for PEG 50000 and relatively high flux late. The laminated membrane with β-chitin or composite membrane with HEC is also very effective for the separation of aqueous ethanol solution by evapomeation. Water molecules are selectively dissolved into the chitin or HEC layer and then predominantly diffused through BC layer.