Highly efficiency and selective recovery of gold using magnetic covalent organic framework through synergistic adsorption and reduction

The recovery of gold from industrial flotsam and electronic waste has attracted significant attention due to the tremendous economic benefits. However, the effective recovery of gold through environmentally friendly and economical methods encounters significant challenges. In this work, a magnetic β-ketoenamine covalent organic framework material, named MTpPa-1, was found to be an superior material for the recovery of Au(III) in water. Impressively, the adsorption capacity is approximately 1737 mg g−1 at pH= 2.0. More importantly, MTpPa-1 can selectively and efficiently capture Au(III) even in the presence of 100 times coexisting ions. This ultra-high selectivity is attributed to the electrostatic interaction, coordination and reduction, in which the catalytic reduction caused by enol-ketone tautomerism was identified as dominated mechanism. Furthermore, the resulting material was of high stability, and its adsorption performance did not decrease significantly after 15 recycles. All these results suggest that MTpPa-1 is a green and sustainable adsorbent, which can selectively capture Au(III), providing an effective and simple way for gold recovery.