Construction of porphyrin and viologen-linked cationic porous organic polymer for efficient and selective gold recovery

Recycling precious metals from electronic waste not only benefits environmental protection, but is also favorable for alleviating resource shortages. Ionic porous organic polymers, as one type of burgeoning material, are regarded as excellent adsorbents due to their high ion density, but their application in precious metal recovery is still very limited. Here, V-PPOP-Br, a highly stable and easy-to-build cationic porous organic polymer, was successfully prepared for the first time. By linking porphyrins with viologens, V-PPOP-Br obtained the characteristics of a hierarchical porous structure, a high ion density skeleton, and a rich nitrogen content, which gave it an ultrahigh adsorption capacity (Qmax = 792.22 mg g-1) and rapid adsorption rate for Au(III). V-PPOP-Br also had an effective Au(III) recovery capability from SIM cards. Mechanism investigation confirmed that this remarkable adsorption performance was attributed to the interplay of ion exchange, redox reactions and coordination. Moreover, V-PPOP-Br had excellent recyclability and could maintain an ultrahigh adsorption efficiency of 81% after eight consecutive adsorption-desorption experiments. These excellent performances as well as the roughly calculated gold recycling economics ($37.37/g V-PPOP-Br) confirmed that it possesses promising potential as an ionic porous material for gold recovery.