Purification of a diluted solution containing nickel using electrodeionization

It was found that the effective diffusion coefficient of Ni2+ in a macroporous strongly acidic cation-exchange resin, which was determined with the electromigration method, depends on acidity and flow rate of the solution. The values of diffusion coefficient were found to be 1.18×10−13–1.9×10−12 m2 s−1. Acidification of the solution prevents formation of insoluble nickel compounds on the surface of particles and membranes. At the same time an increase in flow rate (pressure drop) through the ion exchanger results in a rise of ion transport, probably due to an improvement of packing. The ion exchanger previously loaded with Ni2+ was tested by the electrodeionization process of nickel removal from a diluted solution. Optimal conditions for realizing the discontinuous process were determined. It was found that Ni2+ ions are transported both through the ion exchanger and solution. The solution purification degree reached 40%.