Pervaporation dehydration of isopropanol-water mixtures using chitosan zeolite-a membranes

Pervaporation (PV) dehydration of isopropanol (IPA) using modified chitosan membranes was studied. The membranes were prepared from chitosan and were modified by using zeolite-A. Pre-weighed amount of zeolite-A was added into acidic solvent and stirred to produce homogeneous solution. Chitosan flakes were then added into the solution and stirred overnight. Various ratios of zeolite-A and chitosan from 1:20 to 1:2 were used to produce the modified chitosan membranes. The chitosan-zeolite A solution was casted on glass plate and dried at room temperature. The dried membranes were treated with alkaline solution and were thoroughly washed in deionized water. The hydrophilicity of the membranes was studied through swelling test. The test was carried out in a 90 wt% IPA-water mixture. The result showed that the degree of swelling decreased with the increase of the amount of zeolite-A. The mechanical properties of membranes were also tested for tensile strength and elongation at break. Then the membranes were investigated for the PV separation of IPA-water mixtures at the permeate pressure of 720 mmHg under vacuum. The feed concentration was varied from 0 to 95 wt% IPA and the feed temperature was varied from 30 to 70°C. The results showed that the ratio 1:8 of zeolite-A and chitosan produced the best combination to modify the membrane for the separation of water-IPA mixtures. The structural morphologies of the chitosan filled zeolite-A membranes with ratio 1:8 and 1:2 wt zeolite-A/wt chitosan was studied under Scanning Electron Microscopy (SEM). The results showed that the membranes were dense, no pores were visible. The addition of the zeolite did not alter the structure of the membranes.