N-doped carbon supported-Fe nanoparticles activating persulfate for highly efficient degradation of atrazine: Important contributions of non-radical pathways

It is a challenge to improve the contribution of non-free radical pathways to the degradation of organic pollutants in advanced oxidation process. In this work, we synthesized Fe nanoparticles encapsulated within N-doped carbon (Fe@N-C) through the co-pyrolysis of melamine to Fe 2 O 3 mixtures in different ratios (1:0, 5:1, 1:1, 1:2, 1:5 and 0:1) at various temperatures (700 °C, 800 °C, 900 °C). The results indicate that appropriately increasing the pyrolysis temperature (900 °C) and changing the ratio of melamine to Fe 2 O 3 (1:1) can promote defect degree of Fe@N-C to form more active sites. The characterization results of the XRD, FT-IR, and XPS analysis, revealed that a large amount of pyrrolic N and Fe 0 on the Fe@N-C/900–1:1 surface actively involved in the persulfate activation reaction, and atrazine was quickly and completely removed within 30 min in the system of Fe@N-C/900–1:1-PS. Additionally, the acidic and neutral conditions were beneficial for the PS activation by Fe@N-C/900–1:1. SO 4 •- , ·OH, and 1 O 2 were all involved in the atrazine degradation, among which 1 O 2 contributed the most. The activation energy of the atrazine degradation by the Fe@N-C/900–1:1-PS system was only 33.47 kJ/mol, and the catalyst had a broad pH (3–9) tolerance and good potential in practical applications. • FeNPs@N-C was successfully synthesized by co-pyrolysis of melamine and Fe 2 O 3 . • FeNPs@N-C exhibits carbon nanotube-like structures. • The surface of Fe@N-C/900–1:1 holds a large number of defective structures. • Non-free pathway ( 1 O 2 ) is the dominant contribution to the degradation of atrazine. • Fe/N doping and the defective structure of carbon materials favor non-radical processes.