High-efficiency gold recovery by additive-induced supramolecular polymerization of β-cyclodextrin

• Published in: Nature communications Vol. 14; no. 1; pp. 1284 - 11
• Main Authors: Wu, Huang, Wang, Yu, Tang, Chun, Jones, Leighton O., Song, Bo, Chen, Xiao-Yang, Zhang, Long, Wu, Yong, Stern, Charlotte L., Schatz, George C., Liu, Wenqi, Stoddart, J. Fraser
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 09.03.2023; Nature Publishing Group; Nature Portfolio
• Subjects: 140/131; 140/146; 140/58; 147/135; 639/638/541/960; 639/638/541/961; 704/172/4081; Additives; Adducts; Anions; Aqueous solutions; Assembly; Carbitol; Cyclodextrins; Electronic waste; Energy consumption; Gold; Humanities and Social Sciences; multidisciplinary; Polymerization; Recovery; Resource utilization; Science; Science (multidisciplinary); Supramolecular polymers; β-Cyclodextrin
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-36591-0

Developing an eco-friendly, efficient, and highly selective gold-recovery technology is urgently needed in order to maintain sustainable environments and improve the utilization of resources. Here we report an additive-induced gold recovery paradigm based on precisely controlling the reciprocal transformation and instantaneous assembly of the second-sphere coordinated adducts formed between β-cyclodextrin and tetrabromoaurate anions. The additives initiate a rapid assembly process by co-occupying the binding cavity of β-cyclodextrin along with the tetrabromoaurate anions, leading to the formation of supramolecular polymers that precipitate from aqueous solutions as cocrystals. The efficiency of gold recovery reaches 99.8% when dibutyl carbitol is deployed as the additive. This cocrystallization is highly selective for square-planar tetrabromoaurate anions. In a laboratory-scale gold-recovery protocol, over 94% of gold in electronic waste was recovered at gold concentrations as low as 9.3 ppm. This simple protocol constitutes a promising paradigm for the sustainable recovery of gold, featuring reduced energy consumption, low cost inputs, and the avoidance of environmental pollution. Eco-friendly, efficient, and selective gold recovery technologies are urgently desired to satisfy the increasing demand for gold. Here, the authors report one such technology based on the supramolecular polymerization of second-sphere coordinated adducts formed between β-cyclodextrin and tetrabromoaurate anions.