Efficient bacterial disinfection based on an integrated nanoporous titanium dioxide and ruthenium oxide bifunctional approach.

The increasing lack of drinking water around the globe is of great concern. Although UV irradiation, photocatalysis, and electrocatalysis for bacterial disinfection have been widely explored, the synergistic kinetics involved in these strategies have not been reported to date. Herein, we report on an efficient and cost-effective strategy for the remediation of a model bacterium (E. coli), through the integration of photochemistry and electrochemistry based on a bifunctional electrode, which utilizes titanium (Ti) as the substrate, nanoporous titanium dioxide (TiO2) as a photocatalyst, and ruthenium oxide (RuO2) nanoparticles as an electrocatalyst. The nanoporous TiO2 was grown directly onto a Ti substrate via a three-step anodization process, and its photocatalytic activity was significantly enhanced by a facile electrochemical treatment. A high disinfection rate at 0.62 min-1, with >99.999% bacterial removal within 20 min was achieved using the novel TiO2/Ti/RuO2 bifunctional electrode. Complete bacterial disinfection was attained within 30 min as assessed by a spread plate method. Bacterial survival strategies, including a viable but non-culturable state of the bacteria, were also investigated during the bifunctional treatment process. The novel strategy demonstrated in this study has strong potential to be utilized for water purification and wastewater treatment as an advanced environmentally compatible technology.