Synergistic Inactivation of Airborne Bacteriophages Using a Hybrid Carbon Nanotube Plasma and UV-LED Photocatalytic System

Airborne viral transmission necessitates effective indoor air purification strategies. Conventional methods often face operational challenges, including potential secondary aerosolization and performance degradation under high-humidity conditions. This study evaluates a hybrid control system integrating a multi-walled carbon nanotube (MWCNT) field-emission plasma with a UV-LED/TiO2 photocatalyst to continuously inactivate airborne bacteriophages. The system’s performance was assessed under varying applied voltages and relative humidity (RH) levels. The kinetic results demonstrated that the hybrid configuration yields a synergistic inactivation effect compared to the isolated plasma or photocatalytic treatments. Based on the kinetic enhancement, it is hypothesized that trace ozone generated by the plasma discharge serves as an electron acceptor on the UV-illuminated TiO2 surface, thereby mitigating electron–hole recombination and enhancing the generation of hydroxyl radicals (·OH). Furthermore, the hybrid system exhibited operational resilience under high-moisture conditions, maintaining a robust active inactivation constant (ka = 0.190 min−1) at 70% RH without statistical degradation. This stability indicates that the continuous field emission effectively utilizes ambient moisture for secondary radical generation rather than being quenched by water condensation. Ultimately, this hybrid technology presents a continuous and adaptable engineering control measure for mitigating airborne pathogens in enclosed occupational environments, including those in high-humidity climates.