Hydrothermal synthesis of cobalt ferrite-functionalized Ti3C2Tx MXene for the degradation of Congo red via peroxymonosulfate activation system

Abstract

Cobalt ferrite was functionalized onto two-dimensional MXene nanosheets (CoFe2O4 @MXene) using a hydrothermal method. These functionalized nanosheets were employed as activators to investigate the catalytic degradation of Congo red (CR) through peroxymonosulfate (PMS) activation. The mass ratio of cobalt ferrite in the nanosheets played a significant role in CR degradation, and the optimal cobalt ferrite/MXene mass ratio was determined to be 1:1. With a catalyst dosage of 0.25 g/L and the addition of 0.3 mM PMS, the CoFe2O4 @MXene exhibited an impressive degradation rate, achieving approximately 98.9 % degradation within just 30 min. This rapid degradation was attributed to the enhanced electron transfer efficiency at the Co2+/Co3+, Fe3+/Fe2+ and Ti2+/Ti4+ junctions. Extensive analysis using electron spin resonance spectroscopy and scavenger experiments revealed that singlet oxygen (1O2) played a crucial role as the major oxidative species in the non-radical pathway of CR degradation. Based on the findings, a detailed degradation mechanism, degradation intermediates, and potential pathways were proposed, taking into account the reactive oxidative species involved in the process.