Separation of HCl+NiCl2 mixture by diffusion dialysis

Separation of an aqueous solution of HCl + NiCl2 by diffusion dialysis was investigated in a two-compartment mixed cell with an anion-exchange membrane Neosepta-AFN. The experiments proved that this membrane can be considered a good separator for the mixture mentioned, because nickel chloride is efficiently rejected, while hydrochloric acid permeates well through the membrane. The separation is very effective at high acid concentrations and low concentrations of nickel chloride. The separation efficiency of the membrane was evaluated by the partial flux of nickel chloride. The experiments revealed that the partial flux is very low, i.e. below 3.2%-it decreases with increasing acid concentration, but it increases with increasing content of salt in the solution separated. Moreover, the separation process was quantified by the permeability of the membrane based on four phenomenological coefficients which depend on the initial acid and salt concentrations.