Diffusion Behavior Of Small Molecular Permeates In Polyelectrolyte Membrane

Pervaporation is a new separation process for liquid mixtures developed in the last decade, which was known as one of the most promising separation methods in the future. Based on polyvinyl alcohol (PVA), several kinds of polyelectrolytes such as quaternary ammonium cationic polyvinyl alcohol (QAPVA), anionic polyvinyl alcohol prepared from sulfonated polyvinyl alcohol (SPVA), phosphatic polyvinyl alcohol (PPVA), and carboxymethylated polyvinyl alcohol (CMPVA) were synthesized.In this thesis polyelectrolyte matiearal of PVA having different substitution ratio of cation and anion were selected to form polyelectrolyte complexes (PIC) by solution mixing, and homogeneous membranes was prepared. The swelling characteristics of these polyelectrolyte membranes immersed in dual-solution were measured. The influences of these cation and anion chemical structures and different solutions on the membrane swelling characteristics were discussed.The experiment results show that the swelling characteristics of polyelectrolyte membranes are excelled than the pure PVA membranes, and the raising of the substitution value of the polyelectrolyte membranes will increasing the swelling characteristics of the membranes. It was because that the polyelectrolyte and polyelectrolyte complexes commonly have strong hydrophilicity. With the rising of alcohol concentration in the solution the swelling ratio of the membranes was decreasing, and theα_s of the membranes was increasing. The swelling ratios (SR) of the membrane in the order of ethanol>isopropyl alcohol>tert-butanol, and the swelling selectivity factors (α_s) of the membrane in the order of ethanol