Vertically aligned carbon nanotube membrane: synthesis, characterization and application in salt water desalination

Abstract

Previous studies have used molecular dynamics simulation to assess the feasibility of applying vertically aligned carbon nanotube membranes (VA-CNT) for salt water desalination. The presented report experimentally determined the potential of salt water desalination by employing VA-CNT membranes. The VA-CNT membranes were synthesized through the template-assisted pyrolysis of polybenzimidazole-Kapton inside the pores of anodized aluminum oxide (AAO) and characterized by several techniques. The permeability, salt rejection, and biofouling tendency of VA-CNT membranes were measured in various operating conditions; the results were compared with the performance of a commercial reverse osmosis (RO) membrane (BW30). The VA-CNT membrane permeability was about twofold higher than the permeability of the RO membrane. Furthermore, the VA-CNT membranes had higher stability against biofouling phenomena; they also showed antibacterial activity so that about 70% of the adsorbed cells on the VA-CNT membranes were killed by CNTs tips that were vertically aligned on the membrane surface. The rejection efficiency of the VA-CNT membrane was comparable to that of the commercial RO membrane. Finally, the chlorine stability studies showed that high hypochlorite exposure (48000 ppm.h) did not significantly fail the flux and rejection of the VA-CNT membranes, confirming their chemical stability. This study shows the high capability of the VA-CNT membrane in the water treatment process.