Facile and scale-up synthesis of cyano-functionalized covalent organic frameworks for selective gold recovery

The recovery of gold from waste electronic and electric equipment (WEEE) has gained great attention with the increased number of WEEE, because it can largely alleviate the pressure on the environment and resources. Covalent organic frameworks (COFs) are ideal adsorbents for gold recovery owing to their large surface area, good stability, easily functionalized ability, periodic structures, and definitive nanopores. Herein, a cyano-functionalized COF (COF-CN) with high crystallinity was large-scale prepared under mild conditions for the recovery of gold. The introduction of cyano groups enable COF-CN to exhibit excellent gold recovery performance, which possesses fast adsorption kinetics, high cycling stability, and adsorption capacity up to 663.67 mg/g. Excitingly, COF-CN showed extremely high selectivity for gold ions, even in the presence of various competing cations and anions. The COF-CN maintained excellent selectivity and removal efficiency in gold recovery experiments from WEEE. The facile synthesis of COF-CN and its outstanding selectivity in actual samples make it an attractive opportunity for practical gold recovery. A cyano-functionalized COF (COF-CN) was gram-up prepared under mild conditions. Rapid and selective recovery of gold from the real e-waste sample using COF-CN.