N-Doped Carbon Nanotube Capped Cufe for Tetracycline Removal with Peroxodisulfate Activation Modulating Radical Pathway and Non-Radical Pathway Dominance Over a Wide Ph Range：Coupled Dft /Test and Experiments

Abstract

For the enhancement of the restricted Fe3+/Fe2+ cycling rate and the promotion of the pH adaptability in iron-based catalysts, N-doped carbon nanotubes catalyzing CuFe were applied for structural capping modification. The composite catalysts (CuFe@NCNT) could realize TC removal by modulating the synergistic interaction between radical and non-radical pathways in a wide pH range (3-11), and still achieved about 90% removal rate after five cycles within 30 min. The reaction sites of TC in different pH conditions were calculated from DFT, which was combined with quenching experiments and EPR detections to further determine the intrinsic catalytic mechanism in each pH condition. Toxicity assessment of TC and its degradation intermediates with TEST further verified the eco-friendliness of the CuFe@NCNT/PDS system. Overall, CuFe@NCNT could achieve the utility of multi-pathway activation of PDS, providing an attractive new strategy for the efficient and stable removal of antibiotic wastewater over a wide pH range.

Keywords: peroxodisulfate, N-doped carbon nanotubes, wide pH, radical and non-radical mechanism, DFT calculation and toxicity evaluation