Selective Mineral Recovery from Seawater by Ion-Exchangeable Metal–Organic Framework Glasses

The transition to clean energy and sustainable technologies necessitates securing strategic materials, yet traditional land-based mining is increasingly unsustainable. Seawater holds immense potential as a mineral source, but its intricate ionic composition limits current extraction techniques. Here, we report a family of ion-exchangeable materials by grafting phosphate groups onto metal-organic framework glasses, followed by precise heat and aqueous treatments. This process introduces facile exchangeable ions and exposes active functional groups. The developed materials display progressively enhanced Mg²⁺/Ca²⁺ selectivity as solution complexity increases from binary and ternary mixtures to synthetic seawater. Across three different natural seawater samples, the optimized material achieves Mg²⁺ uptake of 7-10 mg g⁻¹ and Li⁺ uptake of 2-3 mg g⁻¹ within 10 min, highlighting high capacity and rapid kinetics under realistic conditions. Quantitative mechanistic analysis reveals that ion exchange contributes to 72% of the total uptake, while 28% arises from phosphate functional groups and pore surface interactions. This dual-mode sorption mechanism underpins the material's excellent selectivity and rate performance relative to a typical commercial resin. Our work thus presents a promising route for designing efficient adsorbents to extract valuable minerals from unconventional sources and help to secure the raw materials vital for a low-carbon future.