Oxidative hydrothermal carbonization to fabricate versatile magnetic biochar for Fenton-like degradation of phenolic compounds.

Magnetic biochar (MBC) has drawn great attention as a versatile catalyst for advanced oxidation elimination of pollutants from aqueous solution with synergy of iron species and carbon matrix. Herein, an MBC was manufactured by oxidative hydrothermal carbonization employing potassium ferrate as precursor and internal oxidant for Fenton-like degradation of phenols in aqueous solution. This unique oxidative hydrothermal carbonization allowed multiple iron species to be introduced with persistent free radicals (PFRs), providing diverse catalysis sites for activating H 2 O 2 into reactive oxygen species (ROSs) for efficient degradation of phenols. Moreover, graphite structure was generated with abundant oxygen functional groups, benefiting to accelerating Fe³⁺/Fe²⁺ cycle by electron shuttle and transfer. The catalysis degradation efficiency was up to 99.74 % with 44.4 % of total organic carbon (TOC) removal rate for 75 mg L⁻¹ of phenol using 0.2 g L⁻¹ MBC dosage. Satisfactory recyclability was achieved for the MBC as the catalysis degradation efficiency slightly decreased from 99.74 % to 87.95 % after five times recycling. Moreover, the MBC catalysis system exhibited extensive applicability in real water matrices and for degradation of different phenols with high efficiency. Serving as a demonstration of oxidized magnetic biochar for efficient Fenton-like degradation of phenols, this work highlighted the great potential of oxidative hydrothermal carbonization in preparation of high performance magnetic biochar. [Display omitted] • Multiple catalysis sites were introduced for activating H 2 O 2 into diverse ROSs. • Diverse active redox sites facilitated Fe³⁺/Fe²⁺ cycle. • Iron oxides and carbon matrix simultaneously boosted the Fenton-like degradation. • High catalytic activity was achieved with superior recyclability. • Adsorption of degradation intermediates also contributed to removal of TOC. [ABSTRACT FROM AUTHOR]