Highly Efficient and Selective Extraction of Gold by Reduced Graphene Oxide

TL;DR

This paper introduces a reduced graphene oxide (rGO) material with ultrahigh capacity and selectivity for extracting gold from complex sources like e-waste, enabling efficient and scalable gold recycling.

Contribution

The study presents a novel rGO material that combines high gold extraction capacity with exceptional selectivity, advancing e-waste recycling technologies.

Findings

rGO achieves 1850 mg/g gold extraction capacity at 10 ppm gold

rGO selectively extracts gold over 14 other elements

Flow-through process demonstrates scalable gold recovery from e-waste

Abstract

Materials that are capable of extracting gold from complex sources, especially electronic waste (e-waste) with high efficiency are needed for gold resource sustainability and effective e-waste recycling. However, it remains challenging to achieve high extraction capacity to trace amount of gold, and precise selectivity to gold over a wide range of complex co-existing elements. Here we report a reduced graphene oxide (rGO) material that has an ultrahigh extraction capacity for trace amounts of gold (1,850 mg/g and 1,180 mg/g to 10 ppm and 1 ppm gold). The excellent gold extraction behavior is accounted to the graphene areas and oxidized regions of rGO. The graphene areas spontaneously reduce gold ions to metallic gold, and the oxidized regions provide a good dispersibility so that efficient adsorption and reduction of gold ions by the graphene area can be realized. The rGO is also highly selective to gold ions. By controlling the protonation process of the functional groups on the oxidized regions of rGO, it shows an exclusive gold extraction without adsorption of 14 co-existing elements seen in e-waste. These discoveries are further exploited in highly efficient, continuous gold recycling from e-waste with good scalability and economic viability, as exemplified by extracting gold from e-waste using a rGO membrane based flow-through process.