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Study of an Environmentally Friendly Method for the Dissolution of Precious Metal with Ionic Liquid and Iodoalkane

Authors :
Feng Feng
Jiamei Liu
Mingxing Zhao
Lu Yu
Haixin Wang
Chunshan Lu
Qunfeng Zhang
Jia Zhao
Yanxia Sun
Jie Cen
Xiaonian Li
Source :
Metals, Vol 11, Iss 6, p 919 (2021)
Publication Year :
2021
Publisher :
MDPI AG, 2021.

Abstract

Gold as a precious metal resource has high recycling significance. However, the current extraction methods cannot achieve the both efficiency and environmental friendliness. In this paper, we propose a new gold leaching agent, which can leach gold under light condition by mixing iodoform (CHI3) with 1-butyl-3-methylimidazolium dicyanamide (BmimN(CN)2) ionic liquid. Under 25 °C and 13 W incandescent lamp irradiation, the leaching yield of gold can achieve 100 wt%, and the average leaching rate is 945 mg Au/(h·mol·CHI3) (18.9 times of that of the cyanidation method). Through the analysis of the results of radical inhibition experiment, UV-Vis and XPS, a possible leaching mechanism is proposed: the iodine radical generated by light oxidizes Au0 to Au+, and then forms AuN(CN)2 by coordinating with N(CN)2−. Subsequently, the ionic liquid and Au N(CN)2 form a stable [Bmim]·[Au(N(CN)2)2] ion pair structure, further promoting the dissolution reaction. The leaching yield of gold can reach 81.9 wt% and 100 wt%, respectively, when applied to ore and waste electrical and electronic equipment (WEEE); the leaching yield of gold can also reach 100 wt% when applied to a waste catalyst by adding a Soxhlet extraction. The results show that this method is not only efficient, mild, and environmentally friendly, but also has strong adaptability and wide application prospects.

Details

Language :
English
ISSN :
20754701
Volume :
11
Issue :
6
Database :
Directory of Open Access Journals
Journal :
Metals
Publication Type :
Academic Journal
Accession number :
edsdoj.fe64a5c058004eed92aac4b08d6d0100
Document Type :
article
Full Text :
https://doi.org/10.3390/met11060919