Anti-biofouling vertically aligned carbon nanotube membrane for water purification

In present report the performance of vertically aligned carbon nanotube membrane to desalination of salty water was experimentally determined. The VA-CNT membranes were synthesized through the templated-assisted pyrolysis of polybenzimidazole-Kapton inside the pores of anodized aluminium oxide (AAO). The permeability and seawater desalination of VA-CNT membranes were measured in various operating conditions and the results were compared with performance of commercial reverse osmosis (RO) membrane (BW30). The concentration of NaCl in feed stream varied from 2000 ppm to 40000 ppm and trans-membrane pressure of the experiments was adjusted to 20, 30 and 40 bar. The VA-CNT membranes permeability was about two-fold higher than permeability of RO membrane through the various operating conditions. The results indicated that concentration of NaCl has the significant impact on membrane performance so that the rejection of commercial membrane reduced from 98% to 50% by increment of salt concentration from 2000 ppm to 40000 ppm. However, the rejection of VA CNT membrane experienced only 15% reduction in salt rejection. The higher permeability of VA-CNT membrane is the consequence of the friction-less transport of water molecule in to the CNTs. Additionally, the salt rejection efficiency of the VA-CNT membrane was comparable to commercial RO membrane.