A MOF/poly(thioctic acid) composite for enhanced gold extraction from water matrices

With the fast generation of electronic waste (e-waste) and the increasing depletion of metal resources, "urban mining" that can selectively recover gold from secondary resources has attracted great interest. Construction of materials with high extraction capacity and satisfying selectivity in complex aqueous-based matrices still remains challenging. Here, a novel metal-organic framework/polymer composite (Fe-BTC/poly(thioctic acid), denoted as Fe-BTC/pTA) has been newly synthesized and applied for selective gold recovery in different matrices (river water, seawater, and leaching solution of e-waste). Benefiting from the high specific surface area and suitable pore sizes as well as the rational design of active sites, the composite exhibits high adsorption capacity (920 mg/g), high removal efficiency (> 99%), fast kinetics (below 0.1 ppb within 10 min), and good applicability in complex matrices, which are better than those of most reported sulfur-containing adsorbents. Solid-state metallic gold with high purity can be effectively enriched due to the high recyclability and long-term stability of the composite. The material after adsorption can be further applied as a heterogeneous catalyst for water remediation due to the in situ generated gold nanoparticles by the redox reaction between Au(III) ions and the S-containing groups in the composites.