Zn-CNTs-Cu catalytic in-situ generation of H2O2 for efficient catalytic wet peroxide oxidation of high-concentration 4-chlorophenol

Highlights: • Zn-CNTs-Cu was prepared by two-step of infiltration melting and displacement method. • Zn-CNTs-Cu/O₂ degraded 4-CP efficiently in CWPO through in-situ generated H₂O₂. • Mechanism and degradation pathway of 4-CP degradation in CWPO by Zn-CNTs-Cu/O₂ was proposed. 4-chlorophenol (4-CP) with high concentration is difficult to degrade thoroughly by traditional treatment methods due to its high biotoxicity and refractory to bio-degradation. A novel catalytic wet peroxide oxidation (CWPO) system based on Zn-CNTs-Cu catalysts through the in-situ generation of H₂O₂ was constructed and investigated for the degradation of high-concentration 4-CP for the first time. Zn-CNTs-Cu composite was prepared by the infiltration melting-chemical replacement method. The operational factors effect, mechanism, and pathways of Zn-CNTs-Cu/O₂ system for high concentration of 4-CP degradation were systematically performed and discussed. At the optimal experimental conditions, the degradation efficiency of 4-CP through CWPO system with Zn-CNTs-Cu/O₂ achieved 100 %, which was 689 % higher than that of wet oxidation system with O₂ alone. According to the mainly in-situ generated H₂O₂, the strong oxidative OH radical and wet-oxidation effect of O₂, high concentration of 4-CP degraded into small molecular organic matter, even been mineralized into carbon dioxide and water in the Zn-CNTs-Cu/O₂ based CWPO system. Overall, Zn-CNTs-Cu/O₂ CWPO system can efficiently degrade high-concentration 4-CP through the in-situ generation of H₂O₂ without extra replenishment, and it provides a novel method and strategy to the efficient treatment of refractory chlorophenols wastewater.