3D micro–meso-structured iron-based hybrid for peroxymonosulfate activation: performance, mechanism and comprehensive practical application potential evaluation

Metal–organic frameworks (MOFs) have been demonstrated to be promising catalysts in advanced oxidation processes (AOPs), while the poor recyclability due to the powder form limits their practical application. Herein, MIL-88A was successfully embedded in a chitosan matrix for the first time to form 3D micro–meso-structured beads (MIL-88A-CS) by an in situ growth method and the beads were used as heterogeneous peroxymonosulfate (PMS) activators to degrade tetracycline hydrochloride (TC-HCl). 97.1% TC-HCl was removed by the MIL-88A-CS/PMS system in 60 min. The main parameters affecting the TC-HCl degradation efficiency were studied. The sulfate radical (SO4˙−) and hydroxyl radical (˙OH) played dominant roles in the TC-HCl removal. The possible TC-HCl degradation mechanism of the MIL-88A-CS/PMS system was proposed. The excellent catalytic activity of MIL-88A-CS was attributed to the abundant Fe active sites, –COOH groups, and large specific surface area, as well as microporous and mesoporous structures. Reasonable degradation pathways were analyzed by identifying TC-HCl intermediates. Significantly, it is the first time to comprehensively assess the practical application potential of the MIL-88A-CS beads from the perspectives of ecotoxicity, reusability, stability, TC-HCl removal efficiency in actual water environments, and economic applicability. This work provides a promising PMS activator for the removal of emerging contaminants and promotes the practical application of MOFs in wastewater treatment.