Outstanding Molecular Size Recognition and Regulation of Water Permeability on K-Carrageenan-Pullulan Membrane Involved in Synergistic Design of Composite Polysaccharides–Structure

Abstract

Marine biopolymer κ-carrageenan-pullulan composite membrane was successfully prepared. Novel function of polysaccharides (κ-carrageenan (κC) and pullulan (P)) in membrane formation and molecular size screening effect was successfully demonstrated. The mass fraction of κ-carrageenan ( FC ) was a key factor to determine membrane character not only on mechanical strength but also on selected molecular mass transfer. It was defined as the following equation: FC (κC[g]/(P[g] + κC[g])) and changed in desired range (0.33∼0.83). The optimum condition was 70 mM glutaraldehyde for crosslinking and followed the 0.7 M potassium chloride-immersion. The water content was measured and linearly depended on FC . The water permeability of composite membrane was determined from the water mass flux throughput by an ultra-filtration apparatus. The effect of the FC value on the water flux and water content was investigated. The correlation between the mass fraction of κ-carrageenan ( FC ) and the volumetric water flux at 0.15 MPa appeared the strong dependency on the FC values. It suggested that a higher permeation mechanism of water results from higher water content in the composite membrane. Five anionic organic chemicals of molecular weights ranging from 327 to 1017 Da were used in mass transfer examination through the composite membrane. Outstanding molecular size recognition based on the effective diffusion coefficient was appeared. The membrane molecular weight cut-off was established experimentally