Waste control by waste: Fenton-like oxidation of phenol over Cu modified ZSM-5 from coal gangue

Coal gangue and phenol are two main pollutants in coal mining and processing. Using coal gangue as raw material, a series of Cu modified ZSM-5 (Cu/ZSM-5) catalysts were developed to remove phenol through heterogeneous Fenton-like reaction. This procedure implies the concept of waste control by waste. The characterization results showed that Cu modification had no obvious impact on the MFI (Mobile Five) structure of ZSM-5. Copper ions were presented as doping element (substitution of Na and Al ions) and copper oxides on ZSM-5 surface. The XPS spectra suggested the co-existence of Cu²⁺ and Cu⁺. As a consequence of well-defined experimental parameters, 7% Cu/ZSM-5 performed excellent activity and stability for the degradation and mineralization of phenol pollutant, which could degrade phenol completely within 30min and the TOC removal efficiency could reach 63% within 60min and 92% within 8h. ESR and radicals capturing experiments demonstrated that OH and ¹O₂ played the dominant roles in the Fenton-like reaction. In combination with XPS, ESR and catalytic tests, it's found that the redox cycling of Cu⁺/Cu²⁺ played critical roles in accelerating the active radical generation in this Fenton-like system.