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

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(x)10 electrodes. Subsequently, LIG-TiOx filters were fabricated where the complete removal of & SIM;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.

Automated summary

Pathogenic virus inactivation is crucial to ensure safe drinking water. Conventional disinfection methods have drawbacks, while emerging techniques like electrochemical disinfection using graphene-based electrodes provide new opportunities. In this study, titanium suboxide-doped laser-induced graphene (LIG-TSO) electrodes and filters were fabricated for electrochemical virus inactivation. The highest inactivation was achieved using LIG-TiO(x)10 electrodes at 2.5 V, and complete removal of viruses was achieved using LIG-TiOx filters at 2.5 V for MS2 and 10 V for T4 and Phi6. The study identified the inactivation mechanism combining nanofiber-enhanced electroporation and electrochemically generated reactive species. This work will contribute to the design of electrochemical disinfection devices for water purification applications.