PERVAPORATION OF WATER-ETHANOL MIXTURE THROUGH HYDROPHILICALLY MODIFIED POLYIMIDE MEMBRANE

Polyimide of pyromellitic dianhydride (PMDA) and 4,4'-oxydianiline (OD A) was hydrophilically modified by partial replacing of ODA with 3,5-d iaminobenzoic acid (DABA) containing a carboxylic group with two amine groups. Pervaporation experiments of water/ethanol mixture were perfo rmed and the results demonstrated that both flux and permselectivity i ncrease simultaneously with increasing DABA content in polyimide backb one. From the sorption and temperature-dependent permeation behavior, it could be concluded that the diffusivity of permeant plays a major r ole in determining the pervaporation performance rather than the solub ility.