Development of MnO2/γ-Al2O3 catalysts for catalytic ozonation of phenolic wastewater

• HNO 3 modification boosts γ-Al 2 O 3 surface area and enhances ozonation activity. • The 4 % MnO 2 /γ-Al 2 O 3 catalyst shows top phenol removal (92.23 %) and good stability performance over 3 cycles. • Phenol ozonation follows pseudo-first-order kinetics with reaction rate constant ( k ) up to 0.0450 min -1 . Phenolic compounds in industrial wastewater pose significant environmental and health risks due to their toxicity and persistence. This study develops MnO₂/γ-Al₂O₃ catalysts for catalytic ozonation and examines how HNO₃ surface modification and calcination temperature influence γ-Al₂O₃ properties and catalytic performance. The optimized catalyst (MA-25-700-4 %) achieved the highest phenol degradation efficiency (92.23 %) with the fastest reaction rate (k = 0.0450 min⁻¹), outperforming catalysts prepared from unmodified commercial γ-Al₂O₃. Enhanced surface area, mesoporosity, and well-dispersed MnOx species promoted efficient ozone activation through the Mn(IV)/Mn(III) redox cycle, facilitating •OH radical generation. The catalyst also demonstrated good reusability over three catalytic ozonation cycles, with only a moderate decrease in reaction rate (k, reduced by ∼31 % from cycle 1 to cycle 3), confirming structural stability and sustained catalytic activity. These findings highlight the importance of controlled support modification and optimized Mn loading in engineering high-performance MnO 2 /γ-Al 2 O 3 catalysts for advanced treatment of phenolic wastewater.