SWNT-MWNT hybrid filter attains high viral removal and bacterial inactivation

We describe the concept and demonstrate the efficacy of a novel SWNT-MWNT hybrid filter for the removal and inactivation of microbial pathogens from water. The filter is composed of a thin SWNT layer (0.05 mg cm(-2)) on top of a thicker MWNT layer (0.27 mg cm(-2)) supported by a microporous support membrane. The SWNT-MWNT filter exhibits high log removal of several model viruses (MS2, PRD1, and T4 bacteriophages) by depth filtration, which predominantly takes place in the thicker and more uniform MWNT layer. The filter removes all bacteria by a sieving mechanism, with the top SWNT layer providing high levels of inactivation of model bacteria (Escherichia coli K12 and Staphylococcus epidermidis), as well as microbes from river water and treated wastewater effluent. The dual-layer SWNT-MWNT filter lays the framework for new possibilities in point-of-use water filtration.