Metal sorption with extractant‐impregnated macroporous resins. 1. Particle diffusion kinetics

Kinetic measurements were made for the sorption of copper ions from aqueous sulfate solutions with di(2‐ethylhexyl)phosphoric acid‐impregnated Amberlite XAD macroporous resins in finite bath by a batch‐contact time method. The sorption process of copper was first determined to be controlled by particle diffusion using a modified shrinking‐core mechanism, which considered reversibility of the sorption. A more rigorous model based on Fick's law was then applied to justify the applicability of the modified shrinking‐core model to the present sorption systems. The effective particle diffusivity had an order of 10⁻¹² (in m² s⁻¹), which was in agreement with those obtained for chelating ion‐exchange processes.