Visible light-driven photodegradation of triclosan and antimicrobial activity against Legionella pneumophila with cobalt and nitrogen co-doped TiO2 anatase nanoparticles

Current TiO2 photocatalysts used to degrade emergent waterborne pollutants are inefficient due to the usage of UV irradiation, which is scarce in solar light, and generally fall short in reaching its microbial properties. In this study, synthesized cobalt-doped (Co-TiO2) and cobalt and nitrogen co-doped (Co-TiO2-N) anatase nano-catalysts were active in degrading triclosan (TCS), a common antimicrobial agent and prominent aquatic pollutant, under UV and visible light, as well as exhibiting antibacterial activity under UV-A light. The developed Co-TiO2-N catalyst displayed the best photocatalytic activity under UV (365 nm) and Vis (450 nm) LED lights irradiation, achieving nearly complete (> 99%) TCS degradation (10 ppm) in 20 min. The identification of some of the intermediate products was carried out by UHPLC-MS/MS, showing that the TCS is primarily mineralized. Furthermore, the antibacterial responses of both Co-TiO2-N and Co-TiO2 catalysts showed auspicious effects against a major waterborne pathogen, Legionella pneumophila, whereas cobalt doping seems to favor the antibacterial action against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. This work highlighted the potential of cobalt and nitrogen doping of TiO2 for water decontamination, as well as its usage with UV-Vis LED light sources, which is expected to promote photocatalytic research due to its lower cost and extended life span.