Photo- and electro-catalysis for solar disinfection of Escherichia coli-contaminated water using Ag–TiO₂/graphite

Abstract

A titanium dioxide film on a graphite substrate was synthesized by chemical bath deposition from TiCl₄ as precursor and with the surfactant cetyl trimethyl ammonium bromide as a linking and assembling agent. Silver was loaded on the TiO₂ film by electrodeposition at 0.025 A. Water contaminated with Escherichia coli was disinfected under sunlight irradiation by photolysis (Lys), photocatalysis (PC), photoelectrocatalysis (PEC), and electrocatalysis (EC). The highest rate constant, k, was achieved with EC; k was 5.1 × 10⁻² colony forming units (CFU) mL⁻¹min⁻¹. However, auto-oxidation of Ag occurred during EC and PEC. Meanwhile, the rate constant of disinfection by means of PC was lower than EC and PEC, and k was 3.82 × 10⁻² CFU mL⁻¹min⁻¹. Nevertheless, the auto-oxidation of Ag in the Ag–TiO₂/graphite tablet did not occur during the disinfection process.

Keywords:

• photo catalysis
• electro catalysis
• Escherichia coli
• solar disinfection
• Ag–TiO₂/Graphite

Acknowledgments

This research was partially supported by the DIPA project of Sebelas Maret University and the HIBAH Bersaing project of the Directorate General for Higher Education, Indonesia. The supports are greatly appreciated.