Simultaneous recovery of adsorbed rare earth elements and upcycling of spent ion exchange resins into graphene via flash joule heating

The escalating global demand for rare earth elements (REEs) and the mounting environmental burden of spent polymer resins represent two of the most pressing challenges. Here, we introduce an innovative method for the recovery of cerium (Ce), a critical REE embedded in exhausted ion-exchange resins and simultaneous upcycling of the resins into turbostratic graphene by flash Joule heating (FJH). The synthesis process subjects the rare earth contained resin beads to temperatures exceeding 3270 K within milliseconds, ensuring complete pyrolysis of the resin, while volatilizing the embedded REEs, which are subsequently captured via a cold trap system. The complete removal of Ce from the ion-exchange resin is confirmed by the XRD and ICP-AES analysis of the recovered material and the resultant graphene. The synthesized graphene demonstrates excellent structural purity, evidenced by low I D /I G ratio (0.12 ± 0.04), high I 2D /I G ratio (3.0 ± 0.20), expanded interlayer spacing (3.41 ± 0.03 Å), and presence of TS1 and TS2 peaks in the Raman spectra indicating turbostratic stacking with minimal interlayer coupling. Molecular dynamics simulations reveal rapid polymer decomposition and carbon atom reorganization above 3000 K, leading to graphene formation. The process also enables recovery of volatilized Ce up to 71 ± 2.20% efficiency, facilitating its reuse. This technology provides a solvent-free route for upcycling spent ion exchange resin beads into high-value graphene, while simultaneously recovering REEs from the resin matrix.