High-Efficiency Gold Recovery Using Cucurbit[6]uril

• DOI: 10.1021/acsami.0c09673
• Publication Date: 2020-07-10T13:50:00Z
• Authors: Huang Wu; Leighton O. Jones; Yu Wang; Dengke Shen; Zhichang Liu; Long Zhang; Kang Cai; Yang Jiao; Charlotte L. Stern; George C. Schatz; J. Fraser Stoddart
• Keywords: 01 natural sciences; 0104 chemical sciences

Developing an extremely efficient and highly selective process for gold recovery is urgently desired maintaining a sustainable ecological environment. Herein, we report gold-recovery protocol on the basis of instantaneous assembly between cucurbit[6]uril (CB[6]) [AuX4]− (X = Cl/Br) anions. Upon mixing CB[6] with four gold-bearing salts MAuX4 (M H/K, X in aqueous solutions, yellow or brown coprecipitates form immediately, as result multiple weak [Au–X···H–C] hydrogen-bonding [Au–X···C=O] ion-dipole interactions. The efficiency, based CB[6]·HAuCl4 coprecipitation, reaches 99.2% under optimized conditions. In X-ray crystal superstructures, [AuCl4]− anions molecules adopt alternating arrangement to doubly connected supramolecular polymers, while [AuBr4]− are accommodated lattice two-dimensional layered nanostructures composed molecules. DFT calculations have revealed that binding energy (34.8 kcal mol–1) higher than (11.3–31.3 anions, leading improved crystallinity yields CB[6]·MAuCl4 H/K) coprecipitates. Additionally, laboratory-scale protocol, aligned attractive strategy practical gold, was established coprecipitation CB[6]·HAuCl4. use extractant provides us new opportunity develop more processes recovery.