Highly efficient removal of organic contaminants and hydroxylamine hydrochloride enhancement effect based on magnetic iron/nitrogen doped carbon nanolayer

Abstract

Developing highly effective and environmental friendliness Fe-based catalysts have attracted increasing attention. Herein, novel nitrogen-doped carbon nanolayer with Fe0/Fe3C nano-particles (Fe@NCL-900) were innovatively fabricated by a simple solvent-free strategy, pyrolyzed the mixture of 4,6-dihydroxypyrimidine and ferric chloride hexahydrate under 900 ℃. In the presence of peroxymonosulface (PMS), Fe@NCL-900 could remove almost 100% Carbamazepine in 6 min with an amazing apparent first-order constant (kobs) as high as 0.733 min−1, about 72 and even 88 times higher than that of the commercial zero-valent iron and the traditional Fenton system, respectively, which was mainly ascribed to the synergistic effect of high graphite carbon and excellent reducing ability of Fe0. Moreover, high valent iron species (Fe (IV)) and four types of reactive oxygen species (ROS) including hydroxyl radical (•OH), sulfate radical (SO4•-), singlet oxygen (1O2), superoxide radical (O2•-) were detected to play a key role in Carbamazepine removal by electron paramagnetic resonance (EPR) and the radical quenching experiments. Interestingly, it was observed that the addition of hydroxylamine hydrochloride could effectively improve the production of more ROS and the first-order constant was enhanced by 7.6 times (5.593 min−1), completely different from the previous reports that hydroxylamine hydrochloride in high concentrations would inhibit the removal rate. Moreover, the magnetically separable catalyst possessed a wide pH range (2.0–10.0) and superior reusability. This study provides novel insights for manufacturing a promising Fe-based nitrogen-doped catalyst in practical wastewater treatment.