Rapid and long-lasting acceleration of zero-valent iron nanoparticles@Ti3C2-based MXene/peroxymonosulfate oxidation with bi-active centers toward ranitidine removal

Abstract

Advanced oxidation processes (AOPs) can effectively degrade ranitidine, a pharmaceutical that is a typical precursor of nitrosamine dimethylamine (NDMA), an extremely potent human carcinogen. Herein, novel magnetic Ti₃C₂-based MXene nanosheets decorated with nanoscale zero-valent iron particles (nZVIPs@Ti₃C₂ nanosheets) were synthesized to boost catalytic peroxymonosulfate (PMS) activation, exhibiting remarkable reactivity and stability for the rapid removal of ranitidine under mild conditions. The response surface methodology (RSM) confirmed that the initial solution pH and PMS dosage were the main factors affecting the heterogeneous oxidation process. The long-lasting catalytic activity was mainly attributed to the rapid charge transfer between dual electron-rich active centers (≡Fe and ≡Ti), with SO₄˙⁻ and HO˙ derived from PMS activation being responsible for ranitidine degradation, among which SO₄˙⁻ was the major contributor. Density functional theory (DFT) calculations also confirmed that the as-synthesized nZVIPs@Ti₃C₂ nanosheets provided bi-active centers for PMS activation, and this process triggered a series of thermodynamically favorable reactions. This study demonstrates a recyclable oxidation method for the rapid removal of ranitidine, which may be applicable to the degradation of other challenging pollutants.