Effect of carbon nanotube nanochannel on the separation performance of thin-film nanocomposite (TFN) membranes

Abstract

Carbon nanotube (CNT) has gained considerable attention in improving the performance of thin-film composite (TFC) membranes due to their remarkable mechanical, thermal and chemical properties. However, there has few studies referred to the contribution of CNT nanochannel to the enhanced permeability up to now. Herein, the carboxylated-SWCNT (COOH-SWCNT) with small size was inserted in the 1,2-Dioleoyl-sn-glycerol-3-phosphocholine (DOPC) liposomes to synthetic CNT-DOPC liposomes, in which CNT could really function as water-channel. Then, the CNT-DOPC liposomes was incorporated in the polyamide (PA) layer to prepare thin-film nanocomposite (TFN) membranes, in an attempt to evaluate the contribution to membrane permeability caused by CNT nanochannel. Stop-flow results showed that the water permeability of CNT-liposomes was nearly ten times higher than pure DOPC-liposomes, which led to a 71.4 % enhancement of water flux compared to TFC membranes and 25.6 % (induced by CNT nanochannel) than DOPC-liposomes incorporated membranes with a relative high rejection to NaCl about 97.6 %. Besides, the membrane with CNT-liposomes exhibited 89.0 % flux recovery rate with the lowest fouling resistance, especially for the hydraulic reversible fouling resistances (0.70*1012 m−1). This work successfully proved that the CNT nanochannel can be really functioned as water-channel and played a vital role in the permeability enhancement.