Electrodeionization of a Ni2+ solution using highly hydrated zirconium hydrophosphate

Ni2+ transport in zirconium hydrophosphate containing 85% water was investigated with the electromigration method. An effective diffusion coefficient of Ni2+ was found to reach 1.14×10!11 m2 s!1. It was shown that zirconium hydrophosphate can be used for discontinuous Ni2+ removal from diluted solutions also containing Ca2+ and Mg2+ ions. The highest purification degree was realized for nickel (77%) and did not exceed 35% for other cations. Ni2+ ions were shown to be transported not only through the solution, but also through the ion exchanger.

Ni2+ transport in zirconium hydrophosphate containing 85% water was investigated with the electromigration method. The effective diffusion coefficient of Ni2+ was found to reach 1.14×10!11 m2 s!1. This is rather close to the magnitude obtained with the electromigration method for flexible ion-exchange resin [18]. E Ec Ea i l na nc N Ni,c N Ni S t uNi — Concentration of Na+ ions in the ion exchanger, mol m!3 — Concentration of Ni2+ions in the ion exchanger, mol m!3 — Ion concentration in the inlet solution, mol m!3 — Ion concentration in the outlet solution, mol m!3 — Average ion concentration in the center compartment, mol m!3 — Apparent diffusion coefficient of Ni2+ ions in the ion exchanger, m2 s!1 — Applied voltage, V — Cathode potential, V — Anode potential, V — Current density, А m!2 — Ion exchanger bed thickness, m — Amount of ions in the anolyte, mmol — Amount of ions in the catholyte, mmol — Ni2+ ion flux through the cationexchange membrane, mol m!2 s — Ni2+ ion flux through the ion exchanger, mol m!2 s — Membrane (electrode) effective area, m2 — Time, s — Mobility of Ni2+ ions in the ion exchanger, m2 V!1 s!1 Greek δ — Thickness of layer near the membrane, m υ — Rate at which a gravity center of the pore liquid moves, m s!1