In-situ construction of nitrogen-doped porous carbon nanosheets supported well-dispersed Fe3O4 nanoparticles for efficient purification of antibiotic wastewater via peroxydisulfate activation

Abstract

Heterogeneous catalysts composed of transition metal oxides and carbon-based materials have displayed significant potential in persulfates activation for the elimination of diverse refractory organic pollutants. Herein, the nitrogen-doped porous carbon (N-pC) nanosheets supported well-dispersed Fe3O4 nanoparticles (Fe3O4/N-pC) were meticulously designed and fabricated. This fabrication process involved the creation of Fe3+/(CN@PDA) precursor through loading polydopamine-Fe3+ complex on graphitic carbon nitride (g-C3N4) and the following calcination process, resulting in in-situ formation of Fe3O4 nanoparticles on the N-pC nanosheets that were derived from polydopamine coated g-C3N4. The large specific surface area, coupled with accessible Fe2+/Fe3+ species, facilitated the synergy of adsorption and catalysis, enabling the rapid elimination of antibiotics via peroxydisulfate (PDS) activation. The optimal Fe3O4/N-pC catalyst demonstrated a remarkable efficacy in the degradation of tetracycline-hydrochloride (TC), reaching a quasi-first-order kinetic constant of 0.1479 min−1, which was 1.95 times that of the degradation reaction using g-C3N4 (0.0758 min−1). Mechanistic investigations revealed that both radicals (·O2-,·OH and SO4·-) and non-radical (1O2 and electron transfer) oxidation pathways were involved in TC degradation. The toxicities of degradation intermediates were assessed through a bean-sprout planting experiment and the quantitative structure-activity relationship (QSAR) analysis. This work offers some guidance on the preparation and application of heterogeneous catalysts for effectively removing organic contaminants from water.