Extraction of Au(III) by Microbially Reduced Metal–Organic Frameworks

Abstract

Gold is a critical resource in the jewelry and electronics industries and is facing increased consumer demand. Accordingly, methods for its extraction from waste effluents and environmental water sources have been sought to supplement existing mining infrastructure. Redox-mediated treatments, such as Fe(II)-based platforms, offer promise for precipitating soluble Au(III). We hypothesized that microbial generation of Fe(II) in the presence of sorbent metal−organic frameworks could capitalize on the advantages of both biologicaland chemical-driven extraction approaches. Toward this aim, we tested Au(III) removal by Shewanella oneidensis cultured with Fe(III)-based materials (ferrihydrite, Fe-BTC, MIL-100, or MIL-127). Across all tested materials, S. oneidensis generated the highest levels of redox-active Fe(II) (1.99 ± 0.27 mM) when cultured with MIL-127 as a respiratory substrate in a bicarbonate-buffered medium. This translated into superior Au(III) removal performance in terms of both removal rate and capacity (k = 2.55 ± 0.60 h −1 ; Q = 183 mg g −1 ). Unlike other materials tested, MIL-127 also maintained cell viability following repeated Au(III) challenges, enabling the regeneration of Fe(II) in the framework. Together, these effects facilitated the treatment of multiple cycles of Au(III) by S. oneidensis-reduced MIL-127. Overall, this work demonstrates that microbial generation of Fe(II) can facilitate the removal of Au(III), augmenting purely adsorptive platforms. Given the biological and chemical modularity of our system, our results suggest that future optimizations to microbial Fe(II) generation may offer promise for improving Au(III) extraction processes.

Selective and Light-Enhanced Au(III) Recovery by a Porphyrin-Based Metal–Organic Framework: Performance and Underlying Mechanisms

“…Among these materials, MOFs, a family of coordination networks with organic ligands containing potential voids, have demonstrated remarkable achievements in Au recovery. , Besides the porous structure of MOFs that provides abundant sorption sites, MOFs also serve as tunable platforms that capably introduce and anchor electron-rich groups to exhibit high affinity and selectivity to Au­(III). − For instance, nitrogen- and sulfur-containing groups or molecules, such as 5-methylthiophene-2-carboxylic acid, mercapto-1,3,4-thiadiazole, bisthiourea, and thioctic acid, were installed onto the backbone of Cu-BMOF and UiO-66, showing high Au capacities of 300–933 mg/g. Besides coordinating recovery by these active sites, the oxidative feature of Au­(III) was also utilized, which has been proven to be a remarkable strategy responsible for the outstanding recovery capacities of MoS 2 nanosheets (2495 mg/g) and Fe-BTC/PpPDA (934 mg/g). − Through the combination of adsorption and reduction, selective Au recoveries with high efficiencies were achieved.…”

Construction of MoS2@Activated Alumina Beads as Catalysts for Rapid Gold Recovery from Au(S2O3)23– Solution

“…Gold (Au), as a noble metal, was an important mineral resource to the economy, politics, and electronic industry due to its scarcity and good conductivity. 1,2 In a traditional mineral process, gold was obtained from natural ores that successively experienced leaching, adsorption, desorption, electrodeposition reduction, and smelting. Up to date, cyanidation with carbon in pulp (CIP) was the most effective way to recover gold and was thus applied widely in the world.…”

“…Gold (Au), as a noble metal, was an important mineral resource to the economy, politics, and electronic industry due to its scarcity and good conductivity. , In a traditional mineral process, gold was obtained from natural ores that successively experienced leaching, adsorption, desorption, electrodeposition reduction, and smelting. Up to date, cyanidation with carbon in pulp (CIP) was the most effective way to recover gold and was thus applied widely in the world. − However, the hypertoxicity of cyanide has caused serious threat to environmental protection. , With the growing public attention to green development, cyanidation will no longer be suitable for the metallurgical industry in the future.…”