Highly Selective Recovery of Gold by In Situ Magnetic Field-Assisted Fe/Co-MOF@PDA/NdFeB Double Network Gel.

ABSTRACT

There are enormous economic benefits to conveniently increasing the selective recovery capacity of gold. Fe/Co-MOF@PDA/NdFeB double-network organogel (Fe/Co-MOF@PDA NH) is synthesized by aggregation assembly strategy. The package of PDA provides a large number of nitrogen-containing functional groups that can serve as adsorption sites for gold ions, resulting in a 21.8% increase in the ability of the material to recover gold. Fe/Co-MOF@PDA NH possesses high gold recovery capacity (1478.87 mg g-1) and excellent gold selectivity (Kd = 5.71 mL g-1). With the assistance of an in situ magnetic field, the gold recovery capacity of Fe/Co-MOF@PDA NH is increased from 1217.93 to 1478.87 mg g-1, and the recovery rate increased by 24.7%. The above excellent performance is attributed to the efficient reduction of gold by FDC/FC+, Co2+/Co3+ double reducing couple, and the optimization of the reduction reaction by the magnetic field. After the samples are calcined, high-purity gold (95.6%, 22K gold) is recovered by magnetic separation. This study proposes a forward-looking in situ energy field-assisted strategy to enhance precious metal recovery, which has a guiding role in the development of low-carbon industries.