A Facile Approach to Sulfur‐Rich Covalent Organic Frameworks for Selective Recovery of Trace Gold

Abstract

AbstractAs one of the most precious metals with versatile uses, the global production needs of gold are much larger than its deposits. Therefore, it is imperative to recover gold from secondary sources so as to realize resource reuse and environmental protection. Due to the desirable physicochemical properties, covalent organic frameworks (COFs), especially the thiol/thioether‐functionalized sulfur‐rich COFs with strong affinity for Au ions, have exhibited promising prospects for gold recovery. However, their applications are still restricted by the commercially unavailable raw materials and complicated synthesis processes of thiol/thioether‐functionalization. Here, a kind of sulfur‐rich COFs (SCOFs) is designed and synthesized by Schiff base reaction in a single step from common commercial 4,4‐diaminophenyl sulfide and 1,3,5‐triformylbenzene, without any additional post‐synthetic modifications. The structure and physicochemical properties of SCOFs are fully characterized, and the adsorption performance for trace Au (III) ions in water is systematically investigated. The results indicate that SCOFs can efficiently and selectively recover Au (III) ions from dilute aqueous solutions. Considering the commercially available raw materials, simple preparation process, fast adsorption and high selectivity, SCOFs exhibit great potential in the field of the recovery of gold ions from various wastewater of mining industries, metal processing, electronic manufacturing, and scrap.