Revealing the Overlooked\nCatalytic Ability of γ‑Al<sub>2</sub>O<sub>3</sub>: Efficient\nActivation of Peroxymonosulfate for\nEnhanced Water Treatment

Activated alumina (γ-Al<sub>2</sub>O<sub>3</sub>) is one\nof the few nanomaterials manufactured at a ton-scale and successfully\nimplemented in large-scale water treatment. Yet its role in advanced\noxidation processes (AOPs) has primarily been limited to functioning\nas an inert carrier due to its inherently nonredox nature. This study,\nfor the first time, presents the highly efficient capability of γ-Al<sub>2</sub>O<sub>3</sub> to activate peroxymonosulfate (PMS) for selectively\neliminating electron-rich organic pollutants in the presence of Cl<sup>–</sup>. Through experimental and theoretical analysis, we\nrevealed that γ-Al<sub>2</sub>O<sub>3</sub>, characterized by\nuniquely strong Lewis acid sites, enabled robust inner-sphere complexation\nbetween PMS and Al(III) sites, triggering the oxidation of Cl<sup>–</sup> to free chlorine through a distinctive, low-energy-barrier\nEley–Rideal pathway. Such a unique pathway resulted in a 42.7-fold\nincrease in free chlorine generation, culminating in a remarkable\n145.9-fold enhancement in the degradation of carbamazepine (CBZ) compared\nwith the case without γ-Al<sub>2</sub>O<sub>3</sub>. Furthermore,\nthis catalyst exhibited high oxidant utilization efficiency, stable\nperformance in real-world environmental matrices, and sustained long-term\nactivation for over 1206 bed volumes (BV) with a CBZ removal rate\nexceeding 90% in fixed-bed experiments. These favorable features render\nγ-Al<sub>2</sub>O<sub>3</sub> an extremely promising nanomaterial\nfor sustainable water treatment initiatives.