High-permeance metal–organic framework-based membrane adsorber for the removal of dye molecules in aqueous phase

This paper reports on a novel membrane adsorber comprising metal–organic frameworks (MOFs) for water treatment. Two types of MOF (ZIF-8 and ZIF-L) were grown within a porous α-alumina support to form a membrane for the adsorption of a dye molecule, rose bengal, in aqueous phase. The external surface of ZIF-L was shown to exhibit strong affinity for rose bengal. We also observed that small crystals (with a large external surface area) are beneficial to adsorption. The surfactant CTAB was used in the synthesis of ZIF-L-based membrane adsorbers in order to reduce the size of ZIF-L particles and increase the loading of ZIF-L within the membrane. The membrane adsorber synthesized with the highest concentration of CTAB achieved the highest dynamic adsorption capacity. The ZIF-L-based membrane adsorbers exhibited water permeance (approximately 2 × 104 L m−2 bar−1 h−1) far exceeding that of most existing membrane adsorbers.