The recovery of platinum group metals (PGMs) from acidic chloride media using anion exchange resins is strongly influenced by metal speciation, competitive adsorption, mass transfer limitations, and regeneration behavior. This study investigates the adsorption and desorption of platinum(IV), palladium(II), and Rhodium(III) from acidic chloride media using Puromet MTA4801PF, a gel-type strong base anion exchange resin functionalized with pyridinium groups. A three-component Pt(IV)–Pd(II)–Rh(III) chloride system was deliberately employed throughout the adsorption experiments to evaluate the equilibrium and kinetic behavior of the PGMs under simultaneous competition for resin exchange sites, thereby providing a controlled representation of the competitive conditions encountered in spent automotive catalyst chloride leachates. The effects of acidity, temperature, PGM concentration, and contact time on adsorption were investigated, followed by equilibrium, kinetic, and diffusion analyses. Under the investigated multicomponent conditions, Pt(IV) and Pd(II) exhibited rapid and favorable uptake, with the Langmuir model providing a strong empirical representation of their equilibrium behavior and the pseudo-first-order kinetic model providing a slightly better description of their kinetic profiles. Rhodium(III) exhibited slower uptake and a less favorable equilibrium response, for which the Freundlich model provided a comparatively better representation and the pseudo-second-order kinetic model gave a stronger kinetic correlation. Boyd and Weber–Morris analyses further indicated that adsorption involves coupled external and internal mass transfer contributions rather than a single rate-controlling step. Desorption experiments further demonstrated pronounced differences in regeneration behavior, with thiourea providing highly effective recovery of Pt and Pd, while more demanding conditions were required for Rh.
