Core-shell Fe3O4@mesoporous carbon composite for tetracycline degradation via peroxymonosulfate activation

Peroxymonosulfate (PMS) as a powerful oxidant could produce multiple radicals. Due to the advantages of easy recovery and separation, magnetic Fe₃O₄ can be regarded as heterogeneous catalyst in PMS activation for pollutants treatment. However, the intrinsic properties of agglomeration and metal ion leaching limit the further utilization. To promote the catalytic efficiency and stability of Fe₃O₄ catalyst, core-shell Fe₃O₄@mesoporous carbon (Fe₃O₄@MC) composite is prepared to eliminate tetracycline (TC) via PMS activation. Fe₃O₄@MC exhibits obviously spherical morphology, mesoporous structural with the mean particles size and surface area of 280 nm and 212.95 m² g⁻¹. In Fe₃O₄@MC/PMS system, the synergistic interaction of MC shell and inner Fe₃O₄ core results in significantly improvement of the catalytic performance. The effect of important factors including catalyst dose and type, PMS dosage, TC concentration, pH of solution, temperature, co-existing anions and water matrices on degradation process are evaluated. As a result, Fe₃O₄@MC delivers a considerable degradation efficiency of 75.9 % for TC within 60 min, and the cycle efficiency can maintain 87.6 % after five consecutive cycles. PMS activation mechanism including radicals and nonradical pathways is proposed and contributes to the degradation of TC. The remarkable Fe₃O₄@MC composite would promote the development of catalysts for TC degradation and present favorable prospectives in wastewater treatment.