Selective Recovery of Gold from Electronic Waste Using Simple Extraction Technique

(© Wiley-VCH)

Although still underdeveloped, the possibility of recovering gold and other noble metals from electronic waste, especially discarded mobile phones is enormous.

British and American researchers have recently discovered a simple and non-hazardous compound that is capable of selectively extracting gold from an assortment of metals that are typically found in electronic waste. The way to use this selective binding in a simple protocol for recovering gold efficiently is illustrated in the Angewandte Chemie journal.

In comparison to their typical contents in principal mining deposits, gold and other noble metals tend to be significantly enhanced in commercial electrical and electronic gadgets, in particular computers, tablets, and mobile phones. To achieve efficient recovery from waste material, they have to be extracted and isolated in an as inexpensive and eco-friendly manner as possible.

Jason Love at the University of Edinburgh, UK, and partners, have created quite a simple chemical compound with the capacity to bind gold efficiently under the conditions of noble metal leaching from discarded electronics, with the aim to address the issue of poor understanding of the chemistry of solvent extraction of gold,

The researchers identified that a simple principal amide could easily form stable complexes with the gold species leached from the metal assortment. They described the extracted gold species as a blend of aggregates made up of the negatively charged gold chloride complex ion bound by the positively charged amide ligand. They managed to achieve this with the aid of spectroscopic and computational analysis.

The research findings could be highly helpful in preparing efficient extraction and recovery processes, as the researchers wrote: "We anticipate that the fundamental chemical understanding gained here is integral to the development of metal recovery processes."

By adding the principal amide to an aromatic hydrocarbon solvent, the gold species from the hydrochloric acid leaching solution can be extracted. This extraction process was more successful compared to the extraction using commercial reagents. Additionally, the back transfer into the aqueous phase was also accomplished, without having to use supplementary stripping reagents. The two-phase extraction can be explained as a process of selective encapsulation and discharge.

The authors of the research paper concluded that the mechanism "draws parallels with the developments of encapsulation complexes in which intricate entities are assembled in solution."

Their findings could lead to a simple and efficient, inexpensive, and eco-friendly recovery technique of gold from waste.

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