(278b) Highly Selective MOF Thin-Film Nanocomposite (TFN) Membranes for Water Purification

The rapid increase in global demand for high purity water for municipal, agricultural, and industrial applications has stimulated substantial research in highly selective membranes for water purification and desalination. However, state-of-the-art polyamide thin-film composite (TFC) membranes show relatively low rejections particularly to small neutral contaminants such as boron. Aiming to improve the selectivity of the current TFC desalination membranes, amine-functionalized metal-organic frameworks (MOFs), such as UiO-66 and MIL-101(Cr), with good water stability, small particle size, high surface area, and good crystallinity were successfully synthesized and incorporated into the polyamide selective layer of a traditional TFC membrane to fabricate novel thin-film nanocomposite (TFN) membranes. Compared to the unmodified benchmark TFC membrane, the incorporation of amine-functionalized MOF nanoparticles significantly changed the properties of the polyamide selective layer in terms of morphology, hydrophilicity and chemistry, which lead to a significant improvement of membrane separation properties. The best performing TFN membrane shows a relatively high pure-water permeability of 0.56 LMH/bar and a high NaCl rejection of 96.7% at 150 psi. This performance is much higher than that of the benchmark membrane and even better than the state-of-the-art seawater desalination membranes. This study has demonstrated the promising potential of MOF-polymer composite materials for applications related to water purification.