Highly efficient MnNi@NC catalyst for PMS Activation: A Dual-Radical system for sulfamethoxazole degradation in Chloride-Rich wastewater

Document Type

Article

Publication Date

5-15-2025

Department

Department of Manufacturing and Mechanical Engineering Technology

Abstract

In this study, carbon nanotubes (CNTs) doped manganese (Mn) and nickel (Ni) hypervalent metals (MnNi@NC) were synthesized using a two-step pyrolysis strategy. The resulting catalyst was employed to activate peroxymonosulfate (PMS) for the degradation of sulfamethoxazole (SMX). Degradation experiments revealed that 900MnNi@NC exhibited exceptional catalytic activity, achieving a 97.8 % degradation rate of SMX. Mechanistic investigations demonstrated that the degradation process was primarily driven singlet oxygen (1O2) and superoxide radical (O2·-), as confirmed through electron paramagnetic resonance (EPR) spectroscopy and quenching tests. X-ray photoelectron spectroscopy analysis attributed the excellent catalytic performance of 900MnNi@NC to the presence of hypervalent Mn and Ni species, along with abundant nitrogen functionalities. Further stability tests, including variations in pH, the presence of anions, diverse pollutants, and repeated cycles, demonstrated the robust environmental tolerance of the 900MnNi@NC/PMS system. Remarkably, chloride ions (Cl−) were found to significantly enhance SMX degradation. EPR data indicated that the addition of Cl− boosted the generation of O2·-, highlighting the system's potential for treating industrial wastewater containing Cl−. Density functional theory calculations further revealed that the incorporation of bimetallic catalysts increased PMS adsorption energy, extended the O-O bond length, facilitated charge transfer, and ultimately improved degradation performance.

Publication Title

Applied Surface Science

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