Abstract

Ion exchange is a process in which cations (anions) in a liquid are exchanged for cations (anions) on a solid sorbent, maintaining electroneutrality in both phases. Ion-exchange resins consist of synthetic organic polymeric materials generally categorized according to functionality as either strong or weak acids or bases. Some specialty resins contain other appending groups such as thiols or chelates. The composition and the porosity of the polymer matrix are also important to function. Manufacture, stabilities, and regeneration of resins are described. Particular resins effect chromatographic separation in addition to ion exchange. Many resins may be regenerated after use.

The primary application of ion exchange is in softening and deionization of water. Other uses include waste treatment, food processing, catalysis, and purification procedures in the chemical, pharmaceutical, and plating industries. Ion-exchange columns are often used in conjunction with such other purification materials as activated charcoal. Cation exchangers generally outsell anion exchangers.