Photoelectrocatalytic treatment of pentachlorophenol in aqueous solution using a rutilenanotube-like TiO2/Ti electrode

Abstract

Taking pentachlorophenol (PCP) as a reference, we investigated the photoelectrocatalytic degradation of organic pollutants using a rutile nanotube-like TiO₂/Ti film electrode. The nanotube-like TiO₂ electrode was prepared by first oxidizing the surface of a titanium sheet to form rutile TiO₂ and then treating it to form the tubular structure in NaOH aqueous solution. The occurrence of PCP degradation was indicated by the decrease in pH, concentration of PCP and TOC, and by the formation of chloride ions. The photoelectrochemical (PEC) efficiency of the nanotube-like TiO₂/Ti electrode has been determined in terms of degradation of PCP and the incident photo-to-current conversion efficiency (IPCE). The experimental results showed that PCP could be degraded more efficiently by a photoelectrocatalytic process than by a photocatalytic or electrochemical oxidation alone. A significant photoelectrochemical synergetic effect was observed. The kinetic constant of PEC degradation of PCP using a nanotube-like TiO₂ electrode was over 60% higher than that using a TiO₂ film electrode. It is noted that chloride ion and hydrogen ion concentration increased with irradiation time in the PEC degradation of PCP; PCP was gradually mineralized and the complete minimization of PCP took more time than its degradation.