Ion exclusion is one of the processes for separating electrolyte from non-electrolytes or weak electrolytes and its efficiency depends on operating variables. In single-pass experiments, low flow rate, small feed volume and low electrolyte concentration give small H.E.T.P. at constant temperature. It gives better result for separating electrolyte and non-electrolyte mixture. Relationship between H.E.T.P. and these variables obtained from experimental data is asl follows : H.E.T.P.=k（superficial velocity）^0.48∼0.50(Feed volume)^0.24∼0.25(electrolyte concentration)^0.18∼0.20 where the constant k is a function of other variables and the characteristic of systems used.
Recycle procedure makes it possible to obtain a high-grade product.