Accelerated Fe(II) regeneration on Fe-doped oxidized carbon nanotube enabling highly-efficient electro-Fenton process for pollutants removal

Abstract

Heterogeneous electro-Fenton (e-Fenton) is considered a prospective technology for persistent organic contaminants removal that relies on the strongly oxidizing •OH. However, the efficiency of e-Fenton is still low as the sluggish Fe(II) regeneration caused by the difficulty modulating the electronic structure of Fe(III) center. Herein, the Fe-doped oxidized carbon nanotube catalysts (OCNT-Fe) is prepared to accelerate Fe(II) regeneration by introducing electronegative oxygen-containing groups and inducing local charge distribution of Fe(III) center. The OCNT-1Fe exhibits an excellent e-Fenton performance for phenol degradation with a kinetic rate of 0.11 min−1 at pH 6.5, which is the highest among reported state-of-the-art e-Fenton catalysts. Moreover, OCNT-1Fe catalyst is demonstrated to be more energy efficient in coking wastewater treatment with an energy consumption of 6.5 kW h kgCOD−1 than other e-Fenton systems of 9.2–29.7 kW h kgCOD−1. This work offers a new perspective on the high-performance e-Fenton catalysts design by rationally modulating the electronic structure for organic pollutants removal.