TY - JOUR
T1 - High-Efficiency Gold Recovery Using Cucurbit[6]uril
AU - Wu, Huang
AU - Jones, Leighton O.
AU - Wang, Yu
AU - Shen, Dengke
AU - Liu, Zhichang
AU - Zhang, Long
AU - Cai, Kang
AU - Jiao, Yang
AU - Stern, Charlotte L.
AU - Schatz, George C.
AU - Stoddart, J. Fraser
N1 - Funding Information:
This research work was funded by the Center for Sustainable Separations of Metals (CSSM), a National Science Foundation (NSF) Center for Chemical Innovation (CCI), grant number CHE-1925708. This research was also supported in part by the computational resources and staff contributions provided for the Quest High Performance Computing Facility at Northwestern University, which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology. Z.L. acknowledges support from the National Natural Science Foundation of China (No. 21971211) and the Supercomputer Center of Westlake University. We wish to thank Dr. Margaret E. Schott for help with editing.
PY - 2020/8/26
Y1 - 2020/8/26
N2 - Developing an extremely efficient and highly selective process for gold recovery is urgently desired for maintaining a sustainable ecological environment. Herein, we report a highly efficient gold-recovery protocol on the basis of the instantaneous assembly between cucurbit[6]uril (CB[6]) and [AuX4]- (X = Cl/Br) anions. Upon mixing CB[6] with the four gold-bearing salts MAuX4 (M = H/K, X = Cl/Br) in aqueous solutions, yellow or brown coprecipitates form immediately, as a result of multiple weak [Au-X···H-C] (X = Cl/Br) hydrogen-bonding and [Au-X···C=O] (X = Cl/Br) ion-dipole interactions. The gold-recovery efficiency, based on CB[6]·HAuCl4 coprecipitation, reaches 99.2% under optimized conditions. In the X-ray crystal superstructures, [AuCl4]- anions and CB[6] molecules adopt an alternating arrangement to form doubly connected supramolecular polymers, while [AuBr4]- anions are accommodated in the lattice between two-dimensional layered nanostructures composed of CB[6] molecules. DFT calculations have revealed that the binding energy (34.8 kcal mol-1) between CB[6] molecules and [AuCl4]- anions is higher than that (11.3-31.3 kcal mol-1) between CB[6] molecules and [AuBr4]- anions, leading to improved crystallinity and higher yields of CB[6]·MAuCl4 (M = H/K) coprecipitates. Additionally, a laboratory-scale gold-recovery protocol, aligned with an attractive strategy for the practical recovery of gold, was established based on the highly efficient coprecipitation of CB[6]·HAuCl4. The use of CB[6] as a gold extractant provides us with a new opportunity to develop more efficient processes for gold recovery.
AB - Developing an extremely efficient and highly selective process for gold recovery is urgently desired for maintaining a sustainable ecological environment. Herein, we report a highly efficient gold-recovery protocol on the basis of the instantaneous assembly between cucurbit[6]uril (CB[6]) and [AuX4]- (X = Cl/Br) anions. Upon mixing CB[6] with the four gold-bearing salts MAuX4 (M = H/K, X = Cl/Br) in aqueous solutions, yellow or brown coprecipitates form immediately, as a result of multiple weak [Au-X···H-C] (X = Cl/Br) hydrogen-bonding and [Au-X···C=O] (X = Cl/Br) ion-dipole interactions. The gold-recovery efficiency, based on CB[6]·HAuCl4 coprecipitation, reaches 99.2% under optimized conditions. In the X-ray crystal superstructures, [AuCl4]- anions and CB[6] molecules adopt an alternating arrangement to form doubly connected supramolecular polymers, while [AuBr4]- anions are accommodated in the lattice between two-dimensional layered nanostructures composed of CB[6] molecules. DFT calculations have revealed that the binding energy (34.8 kcal mol-1) between CB[6] molecules and [AuCl4]- anions is higher than that (11.3-31.3 kcal mol-1) between CB[6] molecules and [AuBr4]- anions, leading to improved crystallinity and higher yields of CB[6]·MAuCl4 (M = H/K) coprecipitates. Additionally, a laboratory-scale gold-recovery protocol, aligned with an attractive strategy for the practical recovery of gold, was established based on the highly efficient coprecipitation of CB[6]·HAuCl4. The use of CB[6] as a gold extractant provides us with a new opportunity to develop more efficient processes for gold recovery.
KW - coprecipitate
KW - outer surface interaction
KW - precious metal
KW - resource recovery
KW - solid-state superstructure
KW - supramolecular assembly
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U2 - 10.1021/acsami.0c09673
DO - 10.1021/acsami.0c09673
M3 - Article
C2 - 32648728
AN - SCOPUS:85090078166
VL - 12
SP - 38768
EP - 38777
JO - ACS applied materials & interfaces
JF - ACS applied materials & interfaces
SN - 1944-8244
IS - 34
ER -