Efficient and selective gold recovery from e-waste by simple and easily synthesized covalent organic framework

Abstract

With the increase of discarded electronic devices, gold recovery from e-waste has induced great interests. Covalent organic framework (COF) as a new kind of porous crystalline material has great advantages in gold recovery due to its large specific surface area, selective functional groups, regular channels and controllable synthesis. Herein, an abundant hydroxyl groups decorated COF (TzDa-COF) with simplestructure and high crystallinity was prepared for gold recovery. TzDa-COF exhibits a great Au(III) uptake up to 1866 mg·g−1 with high selectivity and fast kinetics, which surpasses most of other COFs with complicated structures and multiple functional groups. Furthermore, dynamic adsorption column experiment for Au(III) in simulated e-waste was conducted, in which at a fast flow rate of 3 mL·min−1 almost a complete Au(III) removal was achieved. By using the density functional theory (DFT), powder X-ray diffraction, infrared spectroscopy and X-ray photoelectron spectroscopy, we demonstrate that the Au(III) recovery mechanism of TzDa-COF mainly consists of coordination and reduction. The performance of TzDa-COF suggests attractive opportunity in practical recovery of gold from e-waste.