Tailoring NiFe2O4 nanoparticles via electron-rich Co centers and abundant redox pairs: boosting peroxymonosulfate activation for micropollutant degradation

Abstract

The pervasive presence of pharmaceutical and personal care products (PPCPs) in water bodies underscores the urgency for the advancement of efficient and sustainable methods for their removal. Peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) have demonstrated significant potential in water purification, with their effectiveness largely hinging on the development of high-performance catalysts. In this study, cobalt-doped nickel ferrite (Co-NFO) nanocatalysts were synthesized using a sol-gel combined with calcination method to enhance PMS activation for the degradation of micropollutants. Characterization results confirmed the successful incorporation of Co into the spinel lattice of NFO, which improved phase purity and electronic properties without significantly affecting textural features. The optimized 2.5%Co-NFO catalyst demonstrated exceptional performance in the degradation of carbamazepine (CBZ), achieving a 92.7% degradation efficiency within 15 min, significantly outperforming the undoped NFO catalyst. The system demonstrated broad applicability across various micropollutants and maintained excellent stability and reusability over multiple reaction cycles. In-depth mechanistic studies, incorporating radical quenching experiments, electron paramagnetic resonance (EPR) analysis, electrochemical measurements, and density functional theory (DFT) calculations, have elucidated that the degradation process is driven by a multitude of reactive species. The enhanced catalytic activity was attributed to the improved electron transfer efficiency and stronger PMS adsorption at Co-active sites. Potential CBZ degradation pathways were proposed, and toxicity assessment indicated a general reduction in the acute toxicity of the generated intermediates. This study introduces an innovative Co-doped magnetic catalyst, which, through the doping process, significantly enhances its catalytic activity for PMS activation, thereby offering a promising solution for efficient water purification.