Equilibrium and mechanism studies of gold(I) extraction from alkaline aurocyanide solution by using fluorine-free ionic liquids

Green Amino Acid Ionic Liquids-Based Aqueous Biphasic Systems for Efficient Extraction of Gold(I) from Alkaline Solution

“…Compared to the FTIR spectrum of the IL-rich phase loaded with gold(I), a new absorption peak is visible at 2141 cm –1 , which ascribes to the stretching vibration of −CN in the aurocyanide complex. The stretching vibration peak of −CN in the IL-rich phase is virtually identical to that observed in a KAu(CN) 2 aqueous solution, as well as in other samples containing Au(CN) 2 – . , Ma et al studied the N236/xylene organic phase loaded with gold(I) by FTIR spectroscopy and found that the −CN stretching vibration peak is located at 2142 cm –1 . Subsequently, the gold(I) state in the quaternary ammonium salt organic phase was further studied by extended X-ray absorption fine structure (EXAFS) spectroscopy.…”

Outstanding Performance of the Deep Eutectic Solvent-Based Aqueous Biphasic System Constructed with Sodium Citrate for a Green Gold Separation

“…Theoretically, large quaternary ammonium salt cations, such as P 4 + , tend to combine with large anions that have small surface charges to form ion pairs, and these enter the organic phase. 46 According to the "perchlorate effect", Au(CN) 2 − is a bulky univalent anion; it can easily combine with P 4 + to form extractable ion pairs. 47 When Au(CN) 2 − is present in the ABS, it easily replaces Br − in the P 4 Br:PEG 1:2 DES to form ion pairs with P 4 + , and it is present in the DESrich phase according to the theory of minimum surface charge density.…”

“…It can be concluded that the coordination environment of Au­(CN) 2 – is unchanged and that it does not coordinate with P 4 Br:PEG 1:2 or other species during extraction. Theoretically, large quaternary ammonium salt cations, such as P 4 + , tend to combine with large anions that have small surface charges to form ion pairs, and these enter the organic phase . According to the “perchlorate effect”, Au­(CN) 2 – is a bulky univalent anion; it can easily combine with P 4 + to form extractable ion pairs .…”

A natural deep eutectic solvent-based aqueous biphasic system coupled with MoS2 photocatalytic reduction for green recovery of gold from thiosulfate solution

“…This is attributed to ClO 4 − having a lower surface charge than Au(S 2 O 3 ) 2 3− . According to the minimum surface charge density theory, 49 ClO 4 − combines more easily than Au(S 2 O 3 ) 2 3− with N + in the NADES through electrostatic interactions. These results further verified that the extraction mechanism of Au(S 2 O 3 ) 2 3− by NADES–ATPS is an anion exchange reaction.…”