Enhanced selective gold recovery from e-waste via synergistic hetero-atom controlled quasi-planar benzoxazine-based covalent organic frameworks

Abstract

Efficient and selective gold recycling from e-waste mixtures is crucial for advancing sustainability, the circular economy, and waste management objectives. However, the complex composition of e-waste and the underdeveloped practical potential of current adsorbents highlight the need for innovative sorbent development. Here, we present quasi-planar, benzoxazine-core-based two-dimensional covalent organic frameworks (COFs) with synergistic hetero-atom control across the network, achieved via a multi-component synthetic approach. These COFs, designed with specific gold interaction sites, were explored for the highly selective recovery of gold from real e-waste mixtures. By tuning the hetero-atom distribution, we achieved an impressive gold uptake capacity of 3467 mg g⁻¹ and over 92% selectivity in presence of 12 competing metal ions from e-waste leachate. These findings underscore the critical role of molecular-level engineering in COF sorbents, paving the way for the practical recovery of noble metals from e-waste.