Selective Separation of Pd(II) on Pyridine-functionalized Graphene Oxide Prepared by Radiation-induced Simultaneous Grafting Polymerization and Reduction

The recovery of precious metals like palladium (Pd) from secondary resources has enormous economic benefits and is in favor of the resources reuse. In this work, we prepared a high-efficient pyridine-functionalized reduced graphene oxide (rGO) adsorbent for selective separation of Pd(II) from simulated electronic waste leachate, by one-pot γ-ray radiation-induced simultaneous grafting polymerization (RIGP) of 4-vinyl pyridine (4VP) from graphene oxide (GO) and reduction of GO. The poly(4-vinyl pyridine)-grafted reduced graphene oxide (rGO-g-P4VP) exhibits fast adsorption kinetics and high maximum adsorption capacity. The adsorption capacity is 105 mg g−1 in the first minute, and reaches equilibrium within 120 min. The adsorption process follows Langmuir model, from which the maximum adsorption capacity of Pd(II) is estimated to be 177 mg g−1. We also proved the adsorption mechanism of Pd(II) on rGO-g-P4VP involves both ion exchange and coordination adsorption by XPS analysis. Most importantly, the loss of...