Mass Transfer Behavior of Solutes in NaCS-PDMDAAC Capsules

The mass transfer behavior of solutes, including diffusion and membrane cutoff characteristics in capsules that were prepared by the interfacial reaction of sodium cellulose sulfate (NaCS) and poly(dimethyldiallylammonium chloride) (PDMDAAC), was studied experimentally. By using the diffusion model developed, the diffusion coefficients of low-molecular-weight solutes, such as glucose, sucrose, ethanol, lactic acid, L-lysine, L-glutamic acid, L-tyrosine, L-tryptophan, and L-phenylalanine, in NaCS-PDMDAAC polyelectrolyte membrane were determined. The values of diffusion coefficients in the membrane were about 2-10% of those in pure water. The experimental results indicated that the encapsulation conditions, such as PDMDAAC concentration and PDMDAAC molecular weight, could affect the structure of NaCS-PDMDAAC membrane and further would lead to the change of diffusion coefficients of solutes in capsules. The molecular weight cutoff (MWCO) is less than 2 kDa, which indicates that the NaCS-PDMDAAC capsule membrane has good cutoff performance and can well obstruct the passing of the membrane by the high-molecular-weight solutes.