Superior sorption capacity and one-step reduction of Au(III) by a novel chitosan-based electrospun fiber mat: A cheap and simple technique

In this study, electrospinning technique was used to synthesize a novel cost-effective fiber mat chitosan-glutaraldehyde-thiourea (CS-Glu-Th) with superior maximum sorption capacity, sorption rate, and selectivity. The sorption results showed that CS-Glu-Th performed perfectly at both low and high concentrations of Au(III), with the maximum sorption capacity above 2.28 x 106 mg/kg at high concentrations and a recovery efficiency of 98.44% at low concentrations; sorption equilibrium was reached in about 5 h. Sorption of Au(III) on CS-Glu-Th was driven by a combination of both electrostatic attraction and coordination interaction with C-N, C--N, and C--S groups. Importantly, 94.55% of the sorbed Au(III) was directly reduced to elemental gold by the electron donor C-N group. Additionally, CS-Glu-Th showed favorable sorption selectivity for Au(III); its recovery effi-ciency reached 97.30% under the interference of co-existing elements (i.e., Cu(II), Ni(II), Pb(II), Zn(II), and Pt (IV)) at a same concentration of 2 mg/L. A cost-benefit analysis showed that if one synthesizes 1 kg of CS-Glu-Th, a profit of 33044.7 RMB can be achieved by recovering Au(III) from an industrial application scenario, equiv-alent to a profit rate of 22.0%. Our findings highlight that the finally-synthesized fiber mat CS-Glu-Th is a promising material to recover gold from the aqueous phase with excellent performance.

Automated summary

Electrospinning was used to synthesize a cost-effective fiber mat CS-Glu-Th with superior sorption capacity, sorption rate, and selectivity for Au(III). The sorption mechanism involved electrostatic attraction and coordination interaction with C-N, C--N, and C--S groups, and C-N efficiently reduced sorbed Au(III) to elemental gold. CS-Glu-Th also showed favorable sorption selectivity for Au(III) under the interference of co-existing elements. Cost-benefit analysis demonstrated the profit potential of CS-Glu-Th for gold recovery from industrial applications.