Prof. Yao-Tung LinLifetime Distinguished Professor
Department of Soil and Environmental Sciences, National Chung Hsing University
Speech Title: Catalyzing Indoor Pathogen Control: Effective Photocatalyst on PMMA Substrate for Visible Light Disinfection
Abstract: Photocatalysis represents a remarkably efficient technique for breaking down organic pollutants through the utilization of reactive oxygen species (ROS). This investigation details the creation of an ecologically favorable photocatalyst using a dip-coating method. The catalyst is grounded in nitrogen-doped TiO2 (N-TiO2) and adhered to polymethyl methacrylate (PMMA). Notably, the PMMA coated with 5 g/L N-TiO2 achieved an impressive transmittance rate of 92%, surpassing prior studies involving the sprinkling technique. This newly developed photocatalyst has proven to be exceptionally effective in eradicating bacterial pathogens when exposed to visible light. With a visible light intensity of 0.54 mW/m2 and the PMMA coated with 5 g/L N-TiO2, complete inactivation (5-log-inactivation) of both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) was attained within a day. This outcome underscores the efficacy of the photocatalyst in purging indoor environments. The N-TiO2-coated PMMA demonstrated heightened disinfection capabilities compared to the N-TiO2 suspension. This enhancement can be attributed to the immobilization of the photocatalyst on PMMA, which facilitated improved ROS production and better interaction between the photocatalyst and bacterial cells. Within the span of 24 hours, disinfection efficiencies were found to be contingent on the dosage of the photocatalyst coating solution and the intensity of visible light. These findings were analyzed using the adapted Hom model. Furthermore, reusability trials exhibited that the N-TiO2-coated PMMA sustained a 99.99% disinfection rate against S. aureus even after undergoing five cycles of photo-oxidation. This underscores its potential for consistent and sustainable disinfection applications. The physical attributes of deactivated bacterial cells were scrutinized using atomic force microscopy, which revealed alterations in bacterial height and surface roughness due to photo-oxidation. To conclude, the dip-coating technique yielded an environmentally friendly N-TiO2-coated PMMA that serves as a cost-effective and potent disinfectant matrix for controlling indoor pathogens under visible light conditions. The newly devised photocatalyst exhibits promising potential for diverse indoor disinfection applications, spanning environments such as hospitals, schools, and other communal spaces.