N-doped Carbon-Encapsulated CoMn Bimetallic Nanocages Anchored on Montmorillonite as Efficient Activators of Peroxymonosulfate for Pollutant Control

Abstract

The development of catalysts with high activity and both economic and environmental benefits is critical and challenging for scaling-up pollutant treatment. Herein, using Prussian blue analogues as precursors, nitrogen-doped carbon-encapsulated CoMn bimetallic nanocages (CMNC) were successfully anchored onto montmorillonite (Mt) to form Mt/CMNC-35 nanocomposites. BPA degradation experiments demonstrated a degradation efficiency of 96.7%, a total organic carbon removal rate of 81.3%, and a chemical oxygen demand removal rate of 92.3% within 20 min in the presence of peroxymonosulfate (PMS). The excellent performance can be attributed to the layered structure and abundant hydroxyl groups of Mt, which not only facilitate the dispersion and immobilization of CMNC but also enhance the mass transfer rate. Mechanism investigation uncovered that the generation of •OH, SO 4•− , 1 O 2 , and O 2 •− was dominated by CMNC, whereas the direct electron transfer process was dominated by the highly graphitized nitrogen-doped carbon layer. Continuous degradation experiments revealed the potential of Mt/CMNC-35 for industrial applications, with degradation efficiencies of 100% and >72.0% for 50 mg/L RhB over 10 days and 50 mg/L BPA over 15 days, respectively. Toxicity analyses of BPA and degradation intermediates demonstrated that the Mt/CMNC-35/PMS system exhibited enhanced detoxification. The present study provides valuable insights into the montmorillonite-based catalysts for sustainable wastewater remediation.