Incorporating Fe3C into B, N co-doped CNTs: Non-radical-dominated peroxymonosulfate catalytic activation mechanism

Abstract

Boron and Nitrogen co-doped carbon nanotubes incorporated iron carbide (Fe3C) nanoparticles (Fe3C@BN-C) were successfully prepared by one-step pyrolysis method employing melamine, ferric chloride and boric acid as precursors. Characterizations indicate that the catalyst has large specific surface area (258.17–305.74 m2/g) and abundant defect sites, which are closely related to the adsorption performance and catalytic efficiency of the catalysts. In the presence of peroxymonosulfate (PMS), the removal rates of Fe3C@BN-C-7, Fe3C@BN-C-8 and Fe3C@BN-C-9 for doxycycline hydrochloride (DOX-H) are 87.0%, 91.9% and 86.0% within 120 min. Fe3C nanoparticles, oxygen-containing functional groups, pyridinic N, pyrrolic N, graphite N and B, N dopants play a vital role in the improvement of catalytic activity. Quenching experiments and electron paramagnetic resonance (EPR) studies show that singlet oxygen (1O2) is dominant reactive oxygen species, demonstrating that the degradation reaction predominantly follows the non-radical oxidation pathway. The possible degradation pathway of DOX-H is proposed and 14 intermediate products are reported for the first time. This work not only provides a novel and valuable catalyst for pharmaceutical wastewater treatment, but also reveals a new perspective for the study of activated PMS dominated by non-radical pathway.