Ultrasound-assisted catalytic activation of peroxydisulfate on Ti₃GeC₂ MAX phase for efficient removal of hazardous pollutants

Herein, Ti₃GeC₂ MAX phase was synthesized using the reactive sintering method and characterized via various techniques. The X-ray diffraction pattern confirmed the successful synthesis of the MAX phase in the hexagonal crystal structure with high purity. Based on the field-emission scanning electron microscopy and high-resolution transmission electron microscopy analysis, layered morphology with the compacted structure was observed. The catalytic activity of the MAX phase was evaluated for activation of peroxydisulfate (PDS) under ultrasound (US) irradiation. Ti₃GeC₂ MAX phase (0.2 g/L) with a bandgap of 1.72 eV demonstrated high capability to activate 0.15 mmol/L of PDS under US irradiation, resulting in 94.7% removal efficiency within 80 min of reaction time. The removal of diverse types of pollutants such as dimethyl phthalate, hydroxychloroquine, and mefenamic acid confirmed the high performance of the Ti₃GeC₂/PDS/US ternary system. The quenching tests indicated that both radical and non-radical pathways are involved in the degradation process, and O₂^•−, O•H, SO₄^•−, and O₂1 were recognized as critical species. In addition, a probable degradation mechanism was proposed. The results provide a promising perspective for the application of MAX phase-based materials in the ternary catalyst/oxidant/US systems for the efficient treatment of organic contaminants. To the best of our knowledge, the present work is the first effort to make use of the Ti₃GeC₂ MAX phase as a desirable catalyst for the removal of organic pollutants applying the catalyst/PDS/US ternary system.