The effect of morphologies of carbon nanotube-based membranes and their leachates on antibacterial property

Carbon nanotube (CNT)-based membranes have been reported to have outstanding potential properties such as extraordinary water permeability, microbial toxicity, and chlorine resistance in water and wastewater treatment. However, aspects of antibacterial property for various morphologies of CNT-based membranes and for the membrane leachate are still unclear. In this study, CNT-based membranes having different morphologies were fabricated and were directly exposed to bacterial cultures to test for bacterial viability. In addition, the antibacterial effect of membrane leachates was evaluated by comparing the viability of bacteria in leached and unleached waters. Neither the CNT-based membranes nor any leaching media inhibited Pseudomonas aeruginosa PA14 (PA14) growth. PA14 grown on any of the CNT-based membranes or in their leaching medium were not inactivated, and only PA14 that directly contacted to the surface of vertically aligned (VA) CNT membranes were inactivated. VA-CNT solid membranes which have the highest packing density of CNTs showed higher antibacterial property. They showed 23 and 6.4 times higher antibacterial property than deposited CNT and even VA-CNT forest membranes, respectively. Acidified membrane surfaces showed two times higher antibacterial property than non-acidified membranes. Especially when VA-CNT solid membranes were acidified, their antibacterial property increased 23-fold. After leaching tests, all VA-CNT membranes showed a 10% increase in antibacterial property. This study provides the first comprehensive comparison of the antibacterial property of diverse CNT-based membranes morphologies and further details the effect of acidification and leaching of CNT membranes on their antibacterial properties.