Synergies of Mn modified Fe-based MOF enhanced catalytic ozonation: charge transfer and multiple sites mechanism

Abstract

The conjoint improvement of catalytic ozonation activity and stability for MOFs materials has always been an urgent challenge. Metal doping offers a viable approach to inspire the interaction between active components and O3 due to the optimization of electronic structure and introduction of surface-active sites. In this work, 88A-Mn catalyst derived from MIL-88A was prepared by loading Mn to MIL-88A with a simple pyrolysis method. The structure and physical characterizations confirmed the coexistence of Fe and Mn in the catalyst. The 88A1-Mn1-350 exhibited the efficient degradation of ibuprofen in catalytic ozonation system, with its degradation rate showing 3.6 times and 2.6 times higher than those of the O3 system and the 88A-T/O3 system, respectively. Mechanism analysis indicated the synergistic effect among Fe/Mn interaction, surface hydroxyl group, and O-C=O group promoted the continuous generation of ROS, including ·OH and ·O2-. Specifically, the regeneration of Fe2+ derived from the Mn doping contributed to the recovery of catalytic activity and played an indispensable role in maintaining high efficiency. In addition, 88A1-Mn1-350 possessed outstanding stability in a wide range of pH (3-11) and the coexistence of anions. It also exhibited the superiority compared with traditional catalysts. This finding provides a feasible modification approach to enhance the property of MOFs materials, and achieves the efficient remove of refractory organics in catalytic ozonation system.