Conventional Ion-Exchange and Chelating Resins for Metal Recovery: A Critical Comparison of Selectivity, Dynamic Performance, Regeneration, and Process Integration

Conventional ion-exchange and chelating resins are widely used for metal recovery, purification, and polishing, yet they are still frequently compared using equilibrium capacity rather than process function. This structured critical review examines how charge-driven exchange and ligand-controlled coordination translate into selectivity, kinetics, breakthrough behavior, regeneration, fouling, resin lifetime, and flowsheet integration. Topic-structured searches covering 2018–31 August 2026 yielded 313 candidate records, of which 110 peer-reviewed publications were retained for critical synthesis. Evidence was weighted from batch equilibrium and kinetic studies through fixed-bed or reactor operation, regeneration, real-matrix validation, pilot or multicolumn demonstrations, and selected industrial-scale applications. Across rare-earth elements, Cu–Ni–Co systems, battery-recycling liquors, Sc/V/Ga separations, Zr/Hf and radionuclide systems, precious metals, and industrial wastewaters, the evidence shows that equilibrium qmax and single-solute distribution coefficients are poor stand-alone indicators of process readiness. Representative dynamic studies report outcomes ranging from a Cu breakthrough capacity of 16.51 mg g−1 to an REE eluate concentration factor of 236×, while selected continuous and industrial-scale studies demonstrate high product purity, sustained metal recovery, and concentrated regenerates when feed chemistry and cycle design are controlled. Conventional and chelating resins are therefore best viewed as complementary rather than substitutive technologies. The review proposes a minimum reporting framework for scale-up-relevant studies based on representative feed chemistry, working capacity, breakthrough criteria, regenerant demand, product purity, multicycle durability, and flowsheet integration. Hybrid flowsheets emerge as a particularly defensible strategy for converting resin selectivity into process value.