Highly efficient electro-peroxone enhanced by oxygen-doped carbon nanotubes with triple role of in-situ H2O2 generation, activation and catalytic ozonation

Abstract

The oxygen-doped carbon nanotubes coated on the carbon felt acted as cathode to enhance the electro-peroxone (OCNT-EP) process. Owing to the introduction of oxygen-containing functional groups and defect sites, the OCNT modified cathode could achieve in-situ H2O2 generation, activation, and catalytic ozonation in the EP process. The OCNT-EP showed a 2.3-folds apparent first-order rate constant (k) compared with the EP process using CNT cathode (CNT-EP) for atrazine (ATZ) degradation. According to the processes comparison, quenching experiments, electron paramagnetic resonance (EPR) analysis and determination of hydroxyl radical, it was proved that more.OH and 1O2 were generated by the in-situ H2O2 activation and catalytic ozonation in the OCNT-EP process. Especially, this process improved pollutants degradation under acidic condition for the in-situ H2O2 activation and catalytic ozonation, expanding the pH application range of the EP process with a lower energy consumption (0.10 kWh/g ATZ). What’ more, the OCNT modified cathode performed excellent stability with 20 cycle tests, and demonstrated all improved degradation rate (21.7%−78.0%) for various pollutants (carbamazepine, sulfamethazine, phenol and 2,4-dichlorophenol). Therefore, the OCNT-EP process could be considered as a promising and enhanced EP process for wastewater treatment.