SULFONATE CONTAINING AROMATIC POLYAMIDES AS MATERIALS OF PERVAPORATION MEMBRANES FOR DEHYDRATION OF ORGANIC-SOLVENTS - HYDRATION, SORPTION,DIFFUSION AND FUNCTIONING

A study of the hydration, sorption and diffusion for water and ethanol within polymer films prepared from aromatic polyamides (condensation of 4-4'-diaminodiphenylamino-2-sulfonate (DADPS) and 4-4'-diaminodiphe nyloxide, taken in different ratios, with isophthaloylchloride) has be en made. Knowledge of the factors controlling sorption and diffusion f or water molecules as compared with alcohol molecules within polyamide films has stimulated the development of pervaporation (PV) membranes prepared from Na salt poly-4,4'-diphenylphthalamide-2,2'-disulfonic ac id. The new PV membrane (Polar-2P) possesses the highest selectivity f or water transport (alpha = 10(4)-10(5)) with dehydration of the water -organic mixtures (acetone, isopropanol, ethylacetate) and a high wate r flux (Q approximate to 0.5-1 kg/m(2) h at 30 mol% H2O). The high loc al concentration of C=O, the presence of sulfonic acid groups and orga nic cations on channel inlets and the inlet size are the factors regul ating the high selectivity of water transport. The entrance of organic molecules such as isopropanol, acetone and ethylacetate into these ch annels becomes difficult due to the larger size of these molecules as compared with the inlet size.