Electrochemical carbon-nanotube filter performance toward virus removal and inactivation in the presence of natural organic matter.

The performance of an electrochemical multiwalled carbon nanotube (EC-MWNT) filter toward virus removal and inactivation in the presence of natural organic matter was systematically evaluated over a wide range of solution chemistries. Viral removal and inactivation were markedly enhanced by applying DC voltage in the presence of alginate and Suwannee River natural organic matter (SRNOM). Application of 2 or 3 V resulted in complete (5.8 to 7.4 log) removal and significant inactivation of MS2 viral particles in the presence of 5 mg L(-1) of SRNOM or 1 mg L(-1) of alginate. The EC-MWNT filter consistently maintained high performance over a wide range of solution pH and ionic strengths. The underlying mechanisms of enhanced viral removal and inactivation were further elucidated through EC-MWNT filtration experiments using carboxyl latex nanoparticles. We conclude that enhanced virus removal is attributed to the increased viral particle transport due to the applied external electric field and the attractive electrostatic interactions between the viral particles and the anodic MWNTs. The adsorbed viral particles on the MWNT surface are then inactivated through direct surface oxidation. Minimal fouling of the EC-MWNT filter was observed, even after 4-h filter runs with solutions containing 10 mg L(-1) of natural organic matter and 1 mM CaCl(2). Our results suggest that the EC-MWNT filter has a potential for use as a high performance point-of-use device for the removal of viruses from natural and contaminated waters with minimal power requirements.