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Ion-exchange resins are versatile materials possessing a modulable framework based on cross-linked co-polymers bearing functional groups that can participate in ion exchange. The trapping of ions occurs along with the accompanying release of other ions on and inside of the resins and thus the process is called ion exchange. They are insoluble matrixes normally in the form of small microbeads, usually white or yellowish.
Fig. 1 Diagram of ion exchange
Ion exchange resins consists of two main types, i.e., cation exchange resins, that exchange positively charged ions, such as sodium, for calcium, and anion exchange resins, that exchange negatively charged ions, such as chloride, for arsenic. Resins are usually made from the polystyrene polymer backbone and differ only by their specific functional groups.
Accordingly, they can therefore be classified into four main groups: (i) cationic resins with strong acid exchange ability, and (ii) with weak acid exchange ability; (iii) anionic resins with strong base exchange ability and (iv) with weak base exchange ability.
Ion-exchange resins find very wide application for the softening of water, the purification of sea water, the extraction of metals from sewer water and rivers, the separation of electrolytes, rare-earth elements, isotopes and amino acids, in the manufacture of foods, in analytical chemistry, etc.
Fig. 2 Main applications of ion-exchange resins
We mainly introduce the following applications:
Ion exchange resins can be used in the water treatment, especially in the water softening and water demineralization processes.
Water softening has been in practice for more than a century and finds its use in a wide range of natural and synthetic products. With the increasing demand for pure water, water softening technology is developing continuously. Basic process of water softening is showed below:
Fig. 3 Process of water softening
Demineralization is the removal of dissolved minerals that form salts when water is evaporated. These salts have corrosive properties and must be removed. Similar to softening, in ion exchange demineralization processes, cation resins are used for the removal of cations, and anion resins are used for the removal of anions.
In general, as industrial requirements have grown, specifications for water quality have become progressively more stringent, and regulations to enforce these have become stricter. Hence the choice of resin types for a particular application becomes increasingly complex.
Ion-exchange resins can be used many processes of sugar industry, including softening of water used for sugar extraction, softening of beet sugar juices before evaporation, the NRS (new regeneration system) process, demineralization of sugar juices before evaporation, color removal from cane sugar syrups after evaporation, sugar recovery from molasses, sucrose inversion, chromatographic separation, glucose demineralization, etc.
Ion-exchange resins can be used in various of chemical industries. For example, in surface finishing and plating shops, metals can be recovered or removed by the using of ion-exchange resins, and they also can be used in the production of chlorine and caustic soda, purification of hydrogen peroxide, removal of phenol from industrial waste, removal of aldehydes, selective removal of various elements, etc.
Various antibiotics use ion exchange and adsorbent resins in their production process. And ion-exchange resins can also be used as release agents, active substances, taste-masking agents, and in chromatographic separation.
In addition to the applications listed above, ion-exchange resins can be used in food and beverage industry, in mining industry (e.g. uranium extraction), in enzyme immobilization, and can act as catalysts.
Alfa Chemistry is a leading manufacturer of ion-exchange resins. We offer ion-exchange resins in various specifications which can be used in many kinds of applications. To place an order or request a quote, please don't hesitate to contact us.
