Separation and Purification Technology, Vol.224, 62-69, 2019
Regeneration of thin-film composite membrane used for permeation of hexane vapors
Thin-film polyamide composite membrane (TFC) is a good representative model of highly permeable membrane. SEM analysis showed that TFC membrane structure is swelled by hexane vapors. Contrary, its porous structure collapsed when the used membrane is stored at dry conditions. The aging of membrane causes significant decrease of both hexane vapors and nitrogen permeances while the selectivity increases tenfold. The study is based on time influence and on wetting by various solvents. Methanol treatment opens and swells the pores of aged membrane. Furthermore, the transport and separation properties were studied after gradual wetting by mutually miscible solvents with decreasing polarity (methanol, isopropanol and hexane) that are commonly used for membrane drying. Surprisingly, this solvent exchange drying procedure leads to a regeneration of the TFC membrane. The regenerated membrane shows the same transport and separation properties as the pristine TFC membrane.