Ultrahigh-flux two-dimensional metal organic frameworks membrane for fast antibiotics removal

Abstract

Two-dimensional metal organic frameworks (2D-MOFs) membrane was constructed by in-situ deriving from CoFe-Layered double hydroxides (CoFe-LDH) on substrate membrane using hydrothermal strategy and LDH is fully converted to the 2D-MOFs based on X-ray diffraction (XRD) patterns. Compared to LDH membrane, 2D-MOFs formed a defect-free layer with higher hydrophilicity (water droplet quickly filtrated through membrane), interlayer space (1.03 nm), more negative charge (zeta potential = −18.4 mV at pH = 7.0) and lower molecular weight cut-off (436.1 Da). As a result, 2D-MOFs membrane presented superior water permeability (flux = 622.9 L m−2 h−1 bar−1) and tetracycline (TC) rejection (98.5%) at wide range of pH (5–9) and concentration (0.002–0.02 mM) of TC solution, superior to most state-of-the-art 2D membranes due to the synergy of fast water transport, molecular sieving and electrostatic repulsion. In addition, it also efficiently rejected other negatively charged antibiotics (e.g., norfloxacin and sulfamethoxazole) with high removal efficiency (>87%), which can break the trade-off between permeability and rejection. What's more, after filtration of simulated pharmaceutical wastewater for 2 days, flux loss and irreversible fouling resistance for 2D-MOFs membrane significantly reduced by 31.6% and 89.9% in comparison to the pristine membrane without the addition of MOFs, respectively; moreover, negligible leaching of 2D-MOFs demonstrated its good anti-fouling performance and stability, which was promising to remediate antibiotics contaminated water.