Enhanced electrochemical oxidation of benzene and toluene in aqueous environments using Sb–SnO2-doped TiO2 nanotubes modified by hydrophobic polytetrafluoroethylene (PTFE)

Abstract

The presence of benzene and toluene in groundwater poses a serious threat to both aquatic ecosystems and human health. The electrochemical removal of these contaminants is primarily hindered by the low generation yield of reactive oxygen species (ROS). Herein, polytetrafluoroethylene (PTFE) was electrodeposited onto the surface of Sb–SnO₂-doped TiO₂ nanotubes (TNT/Sb–SnO₂/5PTFE-300) to enhance electrochemical activity. The resulting nanoelectrode achieved removal efficiencies of 96.2 ​% for benzene and 97.6 ​% for toluene. The minimal variation in the degradation of benzene and toluene following 8 cycles of use verified its stability. Experiments confirmed that •OH was the primary ROS. Hydrophobic surface of the nanoelectrode promoted the one-electron reaction of H₂O oxidation, leading to •OH concentrations that were 54.0 and 27.5 times higher, respectively, than those produced by Ti/Sb–SnO₂, and 4.7 and 2.0 times higher, respectively, than those produced by TNT/Sb–SnO₂-300. Moreover, intermediate products suggested the ring-opening of benzene and toluene, yielding easily degradable small organic molecules. The electrochemical oxidation (EO) process revealed a competitive relationship between benzene and toluene, with toluene exhibiting stronger competitive effects (kinetic constant was 2.1 times that of benzene). The efficient nanoelectrode provide a novel approach for the removal of benzene and toluene from aquatic environments through EO.