Metal sorption with extractant‐impregnated macroporous resins. 2. Chemical reaction and particle diffusion kinetics

The rates of the sorption of zinc ions from aqueous sulfate solutions with di(2‐ethylhexyl)phosphoric acid‐impregnated Amberlite XAD macroporous resins were measured in finite bath by a batch‐contact time method. The sorption process was initially found to be controlled by a combined chemical reaction and particle diffusion process using a provable modified shrinking‐core model. A more rigorous model based on Fick's law was then developed to elucidate the sorption mechanism, and a procedure was suggested to simultaneously determine the reaction rate constant and effective particle diffusivity.