1. A sorbent extraction (taken up and held, as by absorption or adsorption or adhesion of the molecules of liquids, gases, and dissolved substances to the surfaces of solids, as opposed to absorption, in which the molecules actually enter the absorbing medium) of strong electrolytes with an anion-exchange resin in which a cationic monomer has been polymerized, or the reverse.
2. A process based on bifunctional (two functional) ion-exchange resins containing both anion (negatively charged ion) and cation (positively charged ion) adsorption sites, which removes both kinds of ions from solutions.