An efficient peroxymonosulfate activation by Nb2CTx-MXene mediated with CQDs composite catalyst for carbamazepine degradation: Kinetics and mechanistic insights

Nb2CTx-MXene with CQDs-modified catalyst was rationally designed and synthesized. • The composite exhibited highly efficient PMS activation for CBZ degradation. • Synergistic radical and non-radical oxidation pathways were experimentally validated. • Identifying key active sites and the degradation pathways improved understanding of Nb2CTx@CQDs catalytic performance. Persistent organic pollutants present long-term risks to aquatic ecosystems, calling for oxidation processes with well-defined activation mechanisms. In this work, an Nb 2 CTx- MXene composite decorated with ginger-derived carbon quantum dots (Nb 2 CTx@CQDs) was constructed to investigate interfacial peroxymonosulfate (PMS) activation for carbamazepine (CBZ) degradation in water. The surface chemistry, textural properties, and electronic features of the composite were systematically characterized. The Nb 2 CTx@CQDs(5 wt.%)/PMS system achieved 94.7 % CBZ removal within 50 min, corresponding to a pseudo-first-order rate constant k of 0.0598 min -1 under optimized conditions. Density functional theory calculations, together with Liquid chromatography-mass spectrometry (LC-MS) analysis, revealed the evolution of key intermediates and supported a stepwise CBZ degradation pathway. Mechanistic results indicate that PMS activation is governed by coupled radical and non-radical processes, promoted by CQDs-modified Nb 2 CTx surfaces playing a decisive role while, the evaluation of ecotoxicity analysis of CBZ intermediates suggested that they are much less harmful for ecosystem. This study highlights the importance of MXene surface modulation with CQDs for regulating PMS activation pathways and provides mechanistic insights relevant to advanced oxidation processes for the degradation of organic pollutants. Download: Download high-res image (291KB) Download: Download full-size image