Scalable and facile fabrication of magnetic triazine polyimide for high-efficiency gold recovery from e-waste

To promote a circular economy, it is crucial to efficiently recover Au(III) from secondary sources such as discarded electronic products. In this study, a magnetic triazine polyimide (MPI) was synthesized using low-cost melamine (MA) and pyromellitic anhydride (PMDA) as monomers. Attributing to the strong affinity between MPI and Au(III), the adsorption capacity of Au(III) onto the synthesized MPI remained essentially unaltered over a wide range of pH values, reaching a maximum of 876.2 mg/g at pH 2. MPI exhibits a rapid separation capability, thereby facilitating the recovery process. Furthermore, MPI exhibited rapid adsorption efficiency and excellent reusability, maintaining consistent adsorption performance throughout ten adsorption-desorption cycles. Moreover, the resultant MPI achieves efficient recovery of Au(III) (>99 %) from an actual central processing unit (CPU) leach solution, along with high selectivity. This high selectivity can be attributed to a variety of interactions, including coordination and hydrogen bonding as well as the reducing property of MPI. These results demonstrate that MPI holds considerable promise for the recovery of precious metals from second resources.