PERVAPORATION SEPARATION OF WATER ETHANOL THROUGH MODIFIED CHITOSAN MEMBRANES .4. PHOSPHORYLATED CHITOSAN MEMBRANES

The present study investigates the pervaporation performance of novel phosphorylated chitosan membranes to separate water from aqueous ethanol solution. Phosphorylated chitosan membranes were prepared from the reaction of orthophosphoric acid and urea on the surface of chitosan membrane in N,N-dimethylformamide. The phosphorus contents in the membrane varied from 1-80 mg/m2 depending upon the reaction period. Chemical modification, in this case phosphorylation, contributed to an improved pervaporation performance of chitosan membranes. Among the phosphorylated chitosan membranes, PCS-30 containing 56 mg/m2 of phosphorus showed the best pervaporation performance: the flux was ca. 0.2 kg/m2-hr and the selectivity toward water was ca. 600 measured with 90 wt.% ethanol at 70-degrees-C. In comparison with the previously reported sulfonated and carboxymethylated chitosan membranes, permeate flux through the present phosphorylated membrane showed a four-fold increase without the loss of selectivity towards water.