Ion Exchange Technology

Abstract

AbstractSince its discovery more than a century ago, the phenomenon of ion exchange has undergone significant evolution in terms of both theory and practice, especially after the synthesis of organic (polymeric) ion exchangers. No specialty thrives in isolation. The field of ion exchange grew over decades by permeating into myriad areas from deionization to drug delivery. There have been continuous development in the synthesis of new ion exchange materials and processes that now cater to various applications in industries as diverse as power and water utilities, biotechnology, chemical purification, food and beverages, agriculture, pharmaceuticals, microelectronics, and also water treatment. Polymeric ion exchangers, viewed as a strongly ionized electrolyte with low dielectric constants, can be made suitable for various uses including trace contaminant removal in environmental separation, hydrometallurgy, catalysis, product purification, and sustainable industrial processes. Many of these specific interactions can be characterized and enhanced by making modifications to the polymer matrix, covalently attached fixed functional groups, degree of cross‐linking, porosity, and morphology. Affinity for specific ions or selectivity of the ion exchangers plays a critical role and allows one to design ion exchange processes in which complete removal of the target ion from the background of other ions is required. Selectivity of the ion exchangers also influences separation of noble metals and chemical purification operations. An understanding of the basic principles of ion exchange equilibrium and kinetics is important for the development of new materials and processes. In order for an ion exchange process to be economically viable, the ion exchangers need to be regenerable so that they may be used for tens of cycles. Such a constraint demands a tradeoff between the high selectivity of the resin and its regenerability with cost‐effective regenerants. Regulations related to the disposal of spent regenerant have also driven new advancements in the field of ion exchange.