Yolk-shell CoFe2O4@hollow mesoporous carbon spheres for Levofloxacin hydrochloride removal: Synergy enhancement effect of adsorption and degradation

A yolk-shell structured magnetic composite catalyst with hollow mesoporous carbon spheres as the shell and CoFe₂O₄ nanoparticles as the core (CoFe₂O₄@HMCS) was successfully designed and synthesized for peroxymonosulfate (PMS) activation to degrade levofloxacin hydrochloride (LFX). Hollow mesoporous carbon spheres (HMCS) possess tunable hollow mesoporous structures, serving as both an excellent adsorbent and catalyst. However, its adsorptive function in catalytic degradation processes has been easily ignored. This work highlights the remarkable adsorption capacity of CoFe₂O₄@HMCS (q_e = 404.32 mg g⁻¹). During the synergistic process of adsorption and degradation, LFX can be rapidly and efficiently enriched by CoFe₂O₄@HMCS, achieving 93.42 % removal within 60 min through subsequent synergistic degradation. The HMCS can stabilize CoFe₂O₄ under complex reaction conditions, reducing Co/Fe leaching. Simultaneously, the combination of HMCS and CoFe₂O₄ also endows HMCS with magnetic properties, which further enhances the catalytic performance of the composite material. Furthermore, a dual-pathway mechanism for PMS activation was proposed, demonstrating that both radical (SO₄^−• and •OH) and nonradical (direct electron transfer) pathways cooperatively contributed to LFX degradation through PMS activation, with the direct electron transfer mechanism playing a dominant role. Meanwhile, the potential transformation pathways of LFX were elucidated. This research aims to develop a magnetically recoverable catalyst with strong adsorption and catalytic capabilities for more practical water treatment applications.