Separation of Ionized from Nonionized:

The separation of ionized materials from nonionized or slightly ionized materials when both are present in water is accomplished by a process known as ion exclusion. The process utilizes conventional ion exchange resins. If we look at a column of ion exchange resin, it contains three phases; the solid network of resin beads, the liquid inside the beads (resin liquid) and the liquid surrounding the beads (interstitial liquid). Most low molecular weight solutes diffuse freely in and out the resin liquid phase. However, the organic non-ionic solutes tend to exist at the same concentration in both the resin liquid and the interstitial liquid phases.

The ionic materials, because of Donnan membrane effect, exist at a considerably lower concentration in the resin liquid than in the interstitial phase. Thus, if a solution containing ionic and nonionic substances are fed to the column and the column is rinsed with water, the ionic solution will reach the bottom first because it has to essentially displace the interstitial liquid. The non-ionic solution must displace the interstitial liquid and the liquid inside the beads. Thus, the nonionic material will emerge out of the column after the ionic solute has passed out of the column.

Hence, ion exclusion offers a method of deionizing or removing majority of ionic constituents from organic products without the use of heat, electricity and chemical regenerants. Typical examples of applications of ion exclusion are separation of acids and salts from glycerine, alcohol and amino acids, the separation of strongly ionized and weakly ionized materials such as acetic and mineral acids, mono-, di- and triethanolamine and mono-, di- and trichloroacetic acid.