Photocatalytic MOF fibrous membranes for cyclic adsorption and degradation of dyes

Metal–organic frameworks (MOF) have attracted great attention in the field of wastewater treatment. When MOF nanoparticles are used for adsorption applications, the nanoparticles normally have to be separated from the dispersed suspension by filtration or centrifugation for regeneration or recycling. In order to avoid this costly and time consuming process, MOF (NH2-MIL-125) nanofibrous hybrid membranes with photocatalytic properties were successfully fabricated in this study. The MOF membranes were characterized by using XRD, SEM, FTIR, TGA, BET, and UV–Vis. The adsorption (including capacity, mechanism, dynamic, and isotherm) of dyes by the membranes is studied in great detail. The membranes exhibit great adsorption capacity to methylene blue and sodium fluorescein, and the adsorption is dominated by steric hindrance of dye molecule, not the π–π interactions and the zeta potential. Most importantly, the MOF membranes could be easily separated from the dyes solution and regenerated via a visible light catalytic degradation process for recycling, and the photocatalytic mechanism is discussed.