Ultrathin and ultradense aligned carbon nanotube membranes for water purification with enhanced rejection performance

Carbon nanotube (CNT) membranes are promising for high-performance self-assembly membranes in water purification, and their molecular sieving performance depends on the effective pore size of the membranes. For the first time, to enhance the separation selectivity of water purification membranes, we prepared the SACNT membrane with smaller pore sizes, more compact pores with 15 nm thickness and an average 0.88 nm CNT spacing in the observed area for water purification. We found that the aligned CNT membranes exhibited salt rejection 2 times higher than that of membranes prepared by disordered CNTs. It can be explained by the sieving effect. In addition, the adsorption interactions between the CNTs and aromatic rings in dyes also contributed to the improved rejection performance, which was confirmed by the molecular dynamics simulation. Our study represents a significant exploration of enhanced properties for aligned CNT membrane fabricated by a simple method, paving the way for high-performance membrane for water purification.