A review of metal–organic framework-based membranes for the removal of emerging contaminants from water

Metal–organic frameworks (MOFs) have shown significant promise in the removal of contaminants of emerging concern (CECs) from water. The integration of MOFs into forward osmosis (FO), nanofiltration (NF), and ultrafiltration (UF) membranes can reduce membrane fouling, improve the removal of CECs, and enhance water permeability. Thus, the use of MOF-based membranes in water purification has been reviewed in several recent studies, which covered both conventional and emerging contaminants. However, to comprehensively understand how MOF-based membranes work for the removal of emerging contaminants, a systematic review must be conducted in this regard as the removal of emerging contaminants depends heavily on compound properties, water chemistry, membrane properties, and operating conditions. In this review, we focused mainly on various types of MOFs used in FO, NF, and UF membranes. Overall findings have shown that the removal of CECs by MOF-based membranes could be improved by modifying/enhancing the properties of membrane such as porosity/pore structure, surface roughness, hydrophilicity, mechanical strength, chemical stability, fouling resistance, and/or adsorption capacity, while the removal degree and the permeance of the membranes could still vary depending on target compounds and water quality conditions. The main objective of this study was to investigate the contaminant/membrane properties of different MOF-based membranes and their preparation methods and purification performance. This study also briefly discussed potential research areas where knowledge gaps still exist.