Abstract
Some water-soluble metal-chelating agents are introduced into a Donnan dialyzer as the strip agent for the enrichment of nickel ion. The interdiffusion fluxes of Ni2+-Na+ and Ni2+-H+ are found to increase with increasing capability of chelating agent. Experimental results of ion-exchange equilibria indicate that the nickel uptake on the strip-side, membrane-solution interface is reduced in the presence of chelator, which explains the promotion of interdiffusion rate. Effects on the interdiffusion fluxes due to various types of chelating agents, concentrations of chelating agents, concentrations of counterions, and pH value are investigated.
In the presence of strong EDTA ligand, the inter-diffusion process is found to be feed-side, film- and membranediffusion controlled. The integral interdiffusion coefficient of counterions in the ion-exchange membrane are obtained from stirred cell data. An increase of interdiffusion activation energy with increasing bulk concentrations of nickel ion in feed solution is observed.
