Fabrication of water-stable MOF-808 membrane for efficient salt/dye separation

Abstract

Zirconium-based metal-organic framework (Zr-MOF) is considered as promising membrane candidate in terms of its tunable pore aperture, rich functionality, and excellent stability. In this study, we pioneered the fabrication of well-intergrown MOF-808 membrane via facile in situ solvothermal growth on porous α-Al2O3 tube. Owing to an appropriate hexagonal aperture window of 10.1 Å, prepared MOF-808 membrane possessed not only ultrahigh rejection rate for versatile dye molecules (e.g., 99.2% for Malachite green, 99.8% for Methyl blue, 99.6% for Congo red, and 99.3% for Calcein) with no loss in separation performance during 96 h of continuous operation, but also low rejection rate for simple salt (e.g., 6.3% for NaCl), rendering it suitable for efficient removal of various dyes from salt-containing wastewater. The resulting MOF-808 membrane achieved ultrahigh salt/dye separation factor of 287.3 with water permeance of 4.37 L m−2 h−1 bar−1. In addition, the MOF-808 membrane remained crack-free upon exposure to salt, acid, alkali solutions or hot water, indicating outstanding chemical stability, which held great promise for efficient dye extraction from textile wastewater.