Heterogeneous Fenton System Driven by Magnetic Graphene-Like Biochar for Degrading Tetracycline

Abstract

The widespread and prolonged use of tetracycline (TC) leads to seriously threaten to the human health and ecosystems. In this study, we proposed a sustainable strategy for the catalytic degradation of TC with a novel iron-loaded biochar prepared from peanut shells. The magnetic graphene-like biochar (PFGB) was prepared by a one-step pyrolysis-activation-reduction method with peanut shells as the char source and K2FeO4 as the activator and iron source. The PFGB possesses a more complex porous structure, a larger specific surface area, a higher degree of graphitization, and more contents of Fe(III), Fe(II) and Fe0 particles on the surface, resulting in more excellent H2O2 catalytic activity and TC catalytic degradation, compared to the peanut shell biochar (BC) and K2FeO4. In addition, PFGB had high stability and reusability, and could maintain a TC degradation efficiency of more than 90% after five repeated applications. The free radical quenching experiment and electron spin resonance (ESR) analysis revealed that •OH and 1O2 were the main active species in the radical and non-radical pathways, respectively. The mechanism of TC removal by PFGB was a synergistic process between adsorption and catalytic oxidation. The porous graphitic carbon structure and oxygenated groups on the surface facilitated the formation and transformation of the reactive substances, and the redox recycles of Fe(III)/Fe(Ⅱ) were critical steps. Therefore, this study provided a novel heterogeneous Fenton system driven by the PFGB to control the TC pollution in water.

Keywords: Heterogeneous Fenton system, Magnetic graphene-like biochar, Tetracycline, K2FeO4