A novel NH<inf>2</inf>-MIL-88B(Fe)-modified ceramic membrane for the integration of electro-Fenton and filtration processes: A case study on naproxen degradation

Abstract

Process intensification based on innovative coupling between membrane microfiltration and catalytic oxidation technologies has become a promising strategy for water treatment. Here, a surface-nucleated metal–organic framework (MOF) was grown in situ to obtain an NH2-MIL-88B(Fe)-functionalized catalytic ceramic membrane (NH2-MIL-88B(Fe)@CM), whose ability to remove naproxen from water matrices via the so-called electro-Fenton with catalytic ceramic membrane (EFCCM) process was systematically investigated. The physicochemical properties of the NH2-MIL-88B(Fe) and membranes were characterized by XRD, FTIR, XPS and SEM, revealing the formation of a well-defined NH2-MIL-88B(Fe) layer on the porous CM with a thickness of around 13.5 µm, which provides a large amount of active sites for H2O2 activation to generate hydroxyl radical ([rad]OH). The EFCCM treatment of naproxen in Na2SO4 solution under recirculation batch mode yielded almost complete drug removal in 90 min at 50 mA, whereas the stability and catalyst loss tests gave evidence of good membrane reusability for 5 cycles. The treatment of naproxen in urban wastewater confronted severe membrane fouling, but this was effectively mitigated by combining hot water backwash with EF self-cleaning. Finally, the naproxen degradation routes involving 7 byproducts are proposed. This is an effective approach to the fabrication of CCM, which could be used for wastewater treatment in continuous mode as suggested by the minimal NPX content at the membrane outlet.