Photocatalytic disinfection of different airborne microorganisms by TiO2/MXene filler: Inactivation efficiency, energy consumption and self-repair phenomenon

Bacteria, fungi and viruses are airborne microorganisms, which can survive and spread in the form of aerosols, posing a serious threat to human health. A dynamic continuous flow photocatalytic reactor containing TiO2/MXene filler was developed to study the inactivation characteristics of four different microorganisms treated by ultraviolet and photocatalysis. By establishing the kinetic fitting model (−lgNpcN0=εAbΦNE1IrtPC+A), it was known that there were differences in the inactivation efficiency of airborne microorganisms with different microstructures. The introduction of catalysis greatly reduced the energy consumption of disinfection. The electrical efficiency per log order (EE/O) of UV254 inactivated E. coli was reduced from 0.012 to 0.015 kW·h·m−3 to 0.0016–0.0040 kW·h·m−3. Furthermore, the self-repair phenomenon was not obvious in a very short time (40 h) under UV irradiation, but the microbial activity continued to decline after photocatalytic treatment. Short wave ultraviolet had stronger penetration than long wave ultraviolet. High radiation intensity can provide more photons and produce more reactive oxygen species (ROS) for photocatalysis, while too high humidity (RH=95%) will inhibit it. Appropriate residence time (4.3 s) can efficiently treat airborne microorganisms with higher concentration (109 CFU·m−3). These external factors affected the photocatalytic disinfection process of different kinds of microorganisms.