Highly selective recovery of gold from strong acidic wastewater with high-purity by self-driven capture

Abstract

Traditional gold recovery has problems arising from excessive use of chemical reagents, weak gold selectivity, and difficulty in separating solid adsorbents and gold. This work reports a self-driven capture agent, a magnetic-driven MXene/GO hydrogel (MMGH), that is prepared by self-crosslinking encapsulation of Ti3C2 (MXene), GO and NdFeB. Here, we provide a recovery method for physically peeling the gold, which makes the separation process easy without the use of toxic and hazardous chemicals. Isotherm model fitting proves that the MMGH exhibits excellent gold recovery performance (2821.8 mg/g) in a highly acidic environment, and the purity of the recovered gold can reach 99.9 % (24 K). The reason for high gold loading by the MMGH is the synergistic three-drive system (magnetism/adsorption/reduction) of the designed material. The self-driven magnetic field enhances mass transfer, enabling the rapid enrichment of Au(III) by the MMGH, and the selective reducing ability of the MXene drives the reduction of Au(III) on the outer surface. The physical separation relies on the formation of cypress leaf dendritic gold structures due to kinetic regulation by the MMGH. This study pioneered a full-chain separation and recovery method for gold by using selective reduction combined with physical peeling, which meets the demand for low-carbon recovery of gold from industrial waste liquids.