Sustainable Gold Mining from E-Waste: Robust Hollow Magnetic Gold Catchers with High Selectivity and Recyclability

Efficiently recovering precious metals like gold from e-waste is a vital environmental and resource challenge. Adsorption technology is a leading solution because of its simplicity and low cost. In this work, a hollow composite magnetic adsorbent, H-Fe₃O₄@CuS@MSN, was successfully created for the selective recovery of gold. The synthesis began with the production of hollow magnetic Fe₃O₄ nanoparticles (H-Fe₃O₄) through a hydrothermal template method. To boost adsorption selectivity, a CuS layer was deposited in situ on the H-Fe₃O₄ surface. Finally, a protective mesoporous silica (MSN) shell was added over the CuS layer to significantly improve the composite's stability in acidic conditions. Batch adsorption tests identified its maximum Au(III) adsorption capacity, which reached 814 mg g^-1 at pH 5, achieving equilibrium in 530 min. Crucially, the adsorbent retains 86.20% gold-removal efficiency in practical e-waste leachate, alongside 98.61% selectivity in simulated mixtures, proving its robust performance in real-world scenarios. The data aligned with the Langmuir isotherm and pseudo-second-order kinetic models, indicating monolayer adsorption on a uniform surface driven by chemisorption. Notably, the adsorbent maintained efficiency through seven regeneration cycles. This study offers a promising and durable method for the selective separation and efficient extraction of gold from electronic waste.