3D covalent organic framework with crown ether and POSS motifs for selective recovery of Au( <scp>iii</scp> ) and Pd( <scp>ii</scp> ) from highly acidic wastewater

, along with high selectivity for Au(III) and Pd(II) over various interfering ions, such as Pb(II), Cu(II), Al(III) and Fe(III). Stability tests showed that more than 80% of the adsorption efficiency for Au(III) and Pd(II) was retained after five cycles, highlighting the COF's potential for adsorption in highly acidic environments. Mechanism analysis revealed that the nitrogen sites in the COF material are responsible for coordinating with Au(III) and Pd(II). This study provides a new example of synthesizing flexible 3D COFs and offers a promising approach for the recovery of precious metals from wastewater.