MIL-88B(Fe)-coated photocatalytic membrane reactor with highly stable flux and phenol removal efficiency

Abstract

• MIL-88B(Fe)@Al 2 O 3 was used for photocatalytic membrane reactors. • High flux and phenol removal efficiency were obtained using the photocatalytic membrane reactors. • The Fe-clusters of MIL-88B(Fe) acted as reactive sites for the photocatalytic reaction. In this study, MIL-88B(Fe) was successfully prepared and coated onto an Al 2 O 3 substrate. Two photocatalytic membrane reactors (PMRs) for phenol degradation were fabricated using the MIL-88B(Fe)-coated substrates. A coated substrate was either placed into a flat-sheet membrane module to give a photocatalytic flat-sheet membrane reactor (PFMR) or integrated with an Al 2 O 3 hollow fiber membrane module to produce a photocatalytic hollow fiber membrane reactor (PHMR). In the PHMR system, the phenol removal efficiency was significantly enhanced, and the permeate flux remained stable at over 4000 L m –2 h −1 bar −1 . The flux of the PFMR was approximately 80–100 L m –2 h −1 bar −1 ; this lower flux was attributed to the coating and full coverage of MIL-88B(Fe) on the Al 2 O 3 surface. These two systems exhibited recyclability, reusability, and stability over at least three cycles of photocatalytic phenol removal. Characterization of the samples after the reaction illustrated that the iron clusters, which act as the reactive sites, remained stable even though the terephthalate organic linkers were partially destroyed during the photocatalytic reaction. The PMRs developed in this study show promise as effective, feasible, and sustainable systems for wastewater treatment.