Preparation of Cellulose Triacetate Pervaporation Membrane by Ammonia Plasma Treatment

摘要

Homogeneous cellulose triacetate membranes were prepared by the solution-casting method. The surface of this membrane was modified with gaseous plasma of a 10-W discharge power in the presence of ammonia gas at 0.15 Torr pressure. The percentage of weight loss of te CTA membranes was found to be 0.7 for 20 min of treatment time in the ammonia plasma. The contact angle measurement indicated that hydrophilicity of the surface increases. ATR-FTIR spectral analysis showed that the hydrophilicity is mainly derived from the amino groups on the modified surface. SEM studies indicate that no considerable change of surface morphology occurred up to 5 min of treatment time, but a considerable change of surface morphology resulted for treatment of 10 and 20 min. The modified membranes were used for pervaporation studies for separation of an isopropanol-aqueous mixture. These membranes showed excellent selectivity for water. The water flux increases with an increase in treatment time for all concentrations of isopropanol in the feed. The isopropanol flux decreases for initial treatment time (2 and 5 min), but showed an increasing trend for a higher treatment time (10 and 20 min).