Peroxymonosulfate Activation for Efficient Tetracycline Hydrochloride Degradation By Recyclable Mil-88a-Chitosan Beads : Kinetics, Mechanism And Enlightenment for Pratical Application

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 into chitosan matrix for the first time to form porous beads (MIL-88A-CS) by 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 MIL-88A-CS/PMS system in 60 min. The main parameters that influence the TC-HCl degradation efficiency were studied. Sulfate radical (SO4•–) and hydroxyl radical (•OH) played dominant roles in TC-HCl removal. Possible TC-HCl degradation mechanism of by 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, large specific surface area, as well as microporous and mesoporous structures. Reasonable degradation pathways were analyzed by identifying TC-HCl intermediates, which exhibited lower toxicity than TC-HCl. After three cycles, MIL-88A-CS still could degrade 92.0% of TC-HCl. This work provides a promising PMS activator for the removal of emerging contaminants and may solve the practical application problem of powdered catalysts