Catalytic activation of hydrogen peroxide by Cr2AlC MAX phase under ultrasound waves for a treatment of water contaminated with organic pollutants

Abstract

This study aims to investigate the sonocatalytic activation of hydrogen peroxide (H<inf>2</inf>O<inf>2</inf>) using Cr<inf>2</inf>AlC MAX phase prepared by the reactive sintering process. The hexagonal structure of the crystalline MAX phase was confirmed by X-ray diffraction. Moreover, the compacted layered structure of the MAX phase was observed via scanning electron microscopy and high-resolution transmission electron microscopy. Under the desired operating conditions, Cr<inf>2</inf>AlC MAX phase (0.75 g/L) showed suitable potential to activate H<inf>2</inf>O<inf>2</inf> (1 mmol/L) under sonication, thereby allowing a considerable removal efficiency for various organic pollutants, including dimethyl phthalate (69.1%), rifampin (94.5%), hydroxychloroquine (100%), and acid blue 7 (91.5%) with initial concentration of 15 mg/L within 120 min of treatment. Kinetic analysis proved that the degradation reaction followed pseudo-first-order kinetics. Scavenging tests demonstrated that hydroxyl radicals and singlet oxygen were effective species during degradation. Furthermore, a probable mechanism for dimethyl phthalate degradation was suggested according to gas chromatography-mass spectroscopy and nuclear magnetic resonance analyses. The obtained results confirmed the capability of the triple Cr<inf>2</inf>AlC/H<inf>2</inf>O<inf>2</inf>/US process as a promising method for treating contaminated water. © 2023 Elsevier B.V., All rights reserved.