4. Electric current transport in electrolytic solutions

In electrolytic solutions, the charge carriers are solvated ions. What's special about this, compared to electronic conduction, is that both cations and anions participate (in opposite directions) in the transport. The current – voltage relationship is linear, similar to Ohm's law for electronic conductors. The conductivity of an electrolytic solution (measured with a conductivity cell) depends mainly on electrolyte concentration and temperature. Thus, for brines (aqueous NaCl solution) used in the chlor-alkali process [7], resistivity is 1.66 Ω . cm at 90 ˚C and 300 g/L and of the order of 3 Ω . cm at 50 ˚C and 200 g/L.

For industrial applications, therefore, it makes sense to use concentrated electrolyte solutions and high temperatures to increase conductivity and limit diffusion transport effects, the practical limits being the solubility of the electrolyte and...