Electrochemical inactivation of enteric viruses MS2, T4, and Phi6 using doped laser-induced graphene electrodes and filters

Abstract

Pathogenic virus inactivation is crucial to eliminate the substantial risk they cause to human health and to ensure safe drinking water. Conventional water disinfection methods generate harmful disinfection by-products and have high energy demands or the possibility of regrowth of microorganisms. Alternatively, emerging techniques like electrochemical disinfection have opened new opportunities in water treatment by using efficient electrodes to inactivate microbes. Furthermore, graphene-based electrodes have shown their effectiveness at low voltage for electrochemical disinfection. Laser-induced graphene (LIG) is a single-step, low-cost fabrication technique of graphene surfaces, and its catalytic activity can be improved further by doping. In the present study, we have fabricated titanium suboxide (TSO)-doped LIG electrodes and filters in a single step for electrochemical virus inactivation. Three model surrogates with structural resemblance to enteric viruses, viz. bacteriophages MS2, T4, and Phi6, were employed during the disinfection experiments. In the batch mode, under varying voltages and TSO doping concentration, the highest virus inactivation was attained at 2.5 V using LIG-TiO_x10 electrodes. Subsequently, LIG-TiO_x filters were fabricated where the complete removal of ∼6 log was achieved for MS2 at 2.5 V, and for T4 and Phi6 at 10 V. The trend in inactivation efficiency in both operating conditions was MS2 > Phi6 > T4, highlighting the varying susceptibilities between the viruses to disinfection. Furthermore, the viruses' inactivation mechanism was recognized as combining nanofiber-enhanced electric field-induced electroporation and electrochemically generated reactive species. The present work will help to design electrochemical disinfection devices and show how the best efficiency can be achieved for different viruses in water purification applications.