Regulating the Interface Polarity Distribution of Zr-Based MOFs by Amino Acid-Like Ligand Functionalization Enables Efficient Recovery of Gold.

ABSTRACT

The recovery of gold from industrial effluents is crucial for environmental conservation, sustainable resource management, and promoting the green development of gold resources. We designed a Zr-based MOF (UKM-78) by incorporating functional organic ligands that resemble amino groups, using MOFs' inherent sieving effect for ion separation. This novel material exhibited enhanced gold recovery under acidic conditions, with an adsorption capacity three times and an adsorption rate four times higher than those of nonfunctionalized UKM-77. Notably, UKM-78 efficiently captured gold solutions at concentrations as low as 1 ppm and achieved an adsorption rate exceeding 90%, owing to the electrostatic interactions and coordination between its functionalized groups and the synergistic effect of its porous structure. Despite multiple regeneration cycles, UKM-78 retains 99.4% of its adsorption capacity. X-ray photoelectron spectroscopy (XPS), kinetic studies, and thermodynamics collectively demonstrated that Au(III) binding on UKM-78 involved cooperative electrostatic interactions and chemical adsorption through coordination. This study highlights the potential of MOFs for efficient and sustainable recovery of gold from complex waste streams.