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%.

It was found that the effective diffusion coefficient of Ni2+ in Dowex MSC-1 resin, which Ecell Ecathode Eanode — Concentration of Ni2+ions in the ion exchanger, mol m!3 — Concentration of Ni2+ ions in the solution, mol m!3 — Effective size of particles, m — Diffusion coefficient of Ni2+ ions in the ion exchanger, m2 s!1 — Diffusion coefficient of Ni2+ ions in the solution, m2 s!1 — Potential drop through the ion exchanger bed, V — Applied cell voltage, V — Cathode potential, V — Anode potential, V F ilim, H ilim, Ni kH kNi lnNi,c nNi R S T uNi uNi zNi — Faraday constant, A s mol!1 — Limiting current due to H+ transport, A m!2 — Limiting current due to Ni2+ transport, A m!2 — Mass transport coefficient of H+ ions in the solution, m s!1 — Mass transport coefficient of Ni2+ ions in the solution, m s!1 — Ion exchanger bed thickness, m — Amount of Ni2+ ions in the catholyte, mmol — Amount of Ni2+ ions in the ion exchanger, mmol — Gas constant, V C mol!1 K!1 — Effective membrane (electrode) area, m2 — Temperature, K — Mobility of Ni2+ ions in the ion exchanger, m2 V!1 s!1 — Mobility of Ni2+ ions in the soluition, m2 V!1 s!1 — Charge of Ni2+ ions Greek υ υ τ — Rate at which center of gravity of the pore liquid moves, m s!1 — Viscosity of the solution, m2 s!1 — Time, s