Degradation of norfloxacin by highly magnetic CoFe2O4 loaded 0D-CQDS activated PMS: Mechanistic analysis and environmental impacts

Abstract

In this study, carbon quantum dots (CQDs) were loaded onto CoFe₂O₄ spinel oxides through a hydrothermal method to synthesize magnetic nanocomposites (CFOC_0.07). The strong Fe-Co interactions in CFOC_0.07 effectively suppressed Co ion leaching, while the introduction of CQDs exposed additional reactive sites. The conjugated π structure in the CQDs molecule can effectively regulate the electron transfer efficiency of CFOC_0.07 and accelerate the electron transfer in the CFOC_0.07/PMS system. The main active sites Co(III) and Fe(II) on CFOC_0.07 synergize with the ${\text{HSO}}_{\text{5}}^{\bullet \text{-}}$${\text{HSO}}_{\text{5}}^{\bullet \text{-}}$/${\text{SO}}_{\text{5}}^{\bullet \text{-}}$${\text{SO}}_{\text{5}}^{\bullet \text{-}}$ and PMS systems to promote the cycling of Co(II)/Co(III), which further enhances the catalytic ability. Experimental results demonstrated that the CFOC_0.07/PMS system could remove up to 95.6% of Norfloxacin (NOR) under optimal conditions, involving both free radicals (${\text{SO}}_{\text{4}}^{\bullet \text{-}}$${\text{SO}}_{\text{4}}^{\bullet \text{-}}$, •OH, and ${\text{O}}_{\text{2}}^{\bullet \text{-}}$${\text{O}}_{\text{2}}^{\bullet \text{-}}$) and non-free radical (¹O₂) as reactive substances. Additionally, cycling experiments and a dynamic continuous flow reactor showed that CFOC_0.07 exhibited high magnetic properties, durable stability and good recycling performance. Toxicity analysis demonstrated that CFOC_0.07 significantly reduced the biotoxicity of NOR. This study introduces a new mechanism for efficient degradation of organic pollutants and offers innovative insights into water pollution control.