Highly stable thiourea-functionalized polyhedral oligomeric Silsesquioxane adsorbent for efficient and selective gold recovery from E-waste leachate

With the fast pace of technological advancement and the accelerating replacement cycle of electronic devices, the process of extracting gold from electronic waste ( E -waste) has emerged as a pivotal challenge for resource recycling and environmental sustainability. In this work, a series of thiourea-functionalized polyhedral oligomeric silsesquioxane (POSS)-based polymers (POSS@ATU-X) abundant in sulfur (S) and nitrogen (N) active sites was synthesized through a facile one-step functionalization strategy, and its performance and underlying mechanism for Au(III) adsorption were systematically investigated. POSS@ATU-4 delivered a rapid adsorption kinetic profile, with 90% of its maximum adsorption capacity attained within 3 h and equilibrium reached at 6 h. Isothermal adsorption tests revealed an ultra-high maximum adsorption capacity of 2643.64 mg g −1 at 318 K. Notably, POSS@ATU-4 exhibited outstanding selectivity for Au(III) in both multi-metal coexisting systems and actual printed circuit board (PCB) leachate, with its removal rate far exceeding those of other coexisting metal ions. After six consecutive adsorption-desorption cycles, the material retained 99% of its initial adsorption efficiency, demonstrating exceptional structural stability and reusability. Mechanistic studies elucidated that Au(III) removal was governed by the synergistic effects of electrostatic attraction and surface coordination interactions. This work provides a feasible and effective strategy for achieving highly selective and stable gold recovery from acidic E -waste streams, which holds great promise for practical industrial applications.