Synergistic Adsorption–Reduction in NH ₂ -MIL-101(Fe) for Ultraefficient Gold Recovery from E-Waste

The development of high-performance adsorbents with exceptional adsorption capacity, superior selectivity, and excellent regenerability is crucial for sustainable precious metal recovery. Functionalized metal–organic frameworks (MOFs) show particular promise in this regard, where the strategic incorporation of functional groups can significantly enhance adsorption performance. In this study, we developed a series of MIL-101(Fe) with tunable compositions by varying the ratio of the two organic ligands. The amino-functionalized NH 2 -MIL-101(Fe) demonstrated outstanding gold (Au(III)) recovery performance from electronic waste wastewater, achieving an experimentally measured adsorption capacity of 4077.47 mg·g –1 at 308 K while maintaining excellent regenerability over multiple cycles without significant capacity loss. Comprehensive investigation of adsorption kinetics and thermodynamics, along with systematic evaluation of pH effects and competitive ions, revealed the material’s robust performance under various conditions. Remarkably, NH 2 -MIL-101(Fe) exhibited exceptional selectivity for Au(III) recovery, even in complex real leaching solutions from central processing units (CPUs) and random access memory (RAM) containing high concentrations of interfering ions. To facilitate practical application, we successfully immobilized NH 2 -MIL-101(Fe) on expanded perlite, creating a composite material that maintained a high gold recovery efficiency during prolonged operation in simulated wastewater. Mechanistic studies demonstrated that the exceptional performance stemmed from synergistic effects between amino group coordination and Fe-node-mediated reduction, where introduced –NH 2 groups played a pivotal role in both Au(III) adsorption and reduction to Au(0). This work not only presents a highly efficient and selective adsorbent for gold recovery but also provides valuable insights into designing functionalized MOF materials for sustainable resource recovery from electronic waste.