Preparation of Metal–Organic Framework/Polyvinylidene Fluoride Mixed Matrix Membranes for Water Treatment

Abstract

Metal–organic framework (MOF)-based mixed matrix membranes have become a research hotspot in separation field owing to the compatibility between MOF particles and the polymeric matrix. Herein, three types of MOF materials (MW-MIL-101­(Cr), MW-UiO-66, and MW-ZIF-8) were successfully synthesized with the microwave-assisted solvo/hydrothermal method. Also, the reaction times of MW-UiO-66 and MW-MIL-101­(Cr) are effectively shortened to 5 and 30 min, respectively. Subsequently, high-performance MOF/polyvinylidene fluoride (PVDF) mixed matrix membranes were fabricated via the phase inversion method for water desalination. Compared with the pristine PVDF membrane, the introduction of hydrophilic MW-MIL-101­(Cr) and MW-UiO-66 crystals significantly increases water permeability and salt rejection of the mixed matrix membrane because the ordered pore structure is beneficial for selective permeability to salt ions. For the mixed matrix membrane with a PVDF concentration of 20 wt % and MW-UiO-66 doping amount of 30 wt %, water permeability can reach up to 72.57 L·m–2·h–1·bar–1, along with NaCl rejection (96%) being between commercial NF90-4040 (91%) and SWC6-4040 (99%) membranes. In addition, the mixed matrix membrane possesses good cycle stability and potential commercial prospects.

Advances in Metal-Organic Frameworks MIL-101(Cr)

“…The synthesized MIL-101(Cr) demonstrated a high benzene adsorption capacity of 16.5 mmol g −1 . Yin et al [ 36 ] successfully synthesized MIL-101(Cr) with standardized and homogeneous crystals by using the microwave-assisted method with a reaction time of only 30 min at 220 °C via 400 W microwave radiation, which greatly reduced the synthesis time of MIL-101(Cr).…”

Highly Sensitive Ratiometric Fluorescent Flexible Sensor Based on the RhB@ZIF-8@PVDF Mixed-Matrix Membrane for Broad-Spectrum Antibiotic Detection

“…Therefore, RhB@ZIF-8 retains the structure of ZIF-8, which also indicates that the RhB molecule is wrapped in the framework of ZIF-8 instead of being adsorbed on the surface of MOF, effectively preventing the aggregation of the dye molecule RhB and maintaining and enhancing its luminescent properties, and the RhB@ZIF-8 composite was successfully prepared. Furthermore, the XRD pattern of RhB@ZIF-8@PVDF MMMs still has the characteristic peak of ZIF-8, and two weak broad peaks belonging to PVDF appear, indicating that the PVDF membrane does not affect the crystallinity of RhB@ZIF-8 and structural features …”

“…Furthermore, the XRD pattern of RhB@ZIF-8@PVDF MMMs still has the characteristic peak of ZIF-8, and two weak broad peaks belonging to PVDF appear, indicating that the PVDF membrane does not affect the crystallinity of RhB@ZIF-8 and structural features. 36 The microscopic morphologies of RhB@ZIF-8 and RhB@ ZIF-8@PVDF-MMM were observed by using scanning electron microscopy (SEM). Fluorescent dyes are optically stable, but their surroundings can influence their photostability, and the accumulation state of the dyes can significantly diminish their luminescence intensity.…”

Metal–organic framework-based materials: emerging high-efficiency catalysts for the heterogeneous photocatalytic degradation of pollutants in water

“…The microwave-assisted solvothermal/hydrothermal method can be utilized to prepare MOF photocatalysts. For example, Yin et al 37 prepared three types of crystals, namely, MW-MIL-101(Cr), MW-UiO-66 and MW-ZIF-8, via the microwave-assisted solvent/hydrothermal method, and then used the three materials as fillers to prepare membrane materials by rapid phase conversion method for seawater desalination. The pore structure of the mixed membrane material is beneficial for the selective infiltration of salt ions, thus promoting the effect of seawater desalination.…”