- ion-exchange resin
Any of a wide variety of synthetic polymers containing positively or negatively charged sites that can interact with or bind to an ion of opposite charge from a surrounding solution.Light, porous solids in granules, beads, or sheets, they absorb the solution and swell as they attract the target ions; when exhausted, they are removed from use and regenerated by an inexpensive brine or carbonate solution. A solid support of styrene-divinylbenzene copolymer to which are attached sulfonic or carboxylic acid groups is often used to attract and exchange cations (e.g., ions of hydrogen or metals). Quaternary ammonium groups on the solid matrix are used to attract anions (e.g., ions of chlorine). Industrially, the resins are used to soften hard water, purify sugar, and concentrate valuable elements (gold, silver, uranium) from their ores. In the laboratory they are used to separate and concentrate substances and sometimes as catalysts. Zeolites are minerals with ion-exchange properties.
* * *any of a wide variety of organic compounds synthetically polymerized (polymer) and containing positively or negatively charged sites that can attract an ion of opposite charge from a surrounding solution. The resins commonly consist of a styrene-divinylbenzene copolymer (high molecular weight substance), although other compositions, such as methacrylic acid–divinylbenzene and phenol-formaldehyde polymers, are also employed. The electrically charged groups are commonly sulfonic or carboxylic acid salts or quaternary ammonium salts. Polymers containing acid groups are classified as acid, or cation, exchangers because they exchange positively charged ions (ion), such as hydrogen ions and metal ions; those containing ammonium groups are considered basic, or anion, exchangers because they exchange negatively charged ions, usually hydroxide ions or halide ions.Ion-exchange resins are light and porous solids, usually prepared in the form of granules, beads, or sheets. When immersed in solution, the resins absorb the solution and swell; the degree of swelling is dependent on the polymeric structure and the total ion concentration of the solution.Resins of suitable chemical compositions and physical properties may be synthesized at will for specific ion-exchange applications; thus, they comprise the bulk of synthetic ion-exchange materials used in the laboratory and industry. In industrial and domestic applications, ion-exchange resins are used for the removal of calcium, magnesium, iron, and manganese salts from water (water softening), for purification of sugar, and for concentration of valuable elements, such as gold, silver, and uranium from mineral ores. In chemical analysis, ion-exchange resins are used for the separation or concentration of ionic substances, and in chemical synthesis, some ion-exchange resins have been used as effective catalysts, notably in esterification and hydrolysis reactions.Two separate types of resins are commonly classed as ion-exchange resins, although their functions do not involve an interchange of ions. These are the chelating resins and the electron-exchange resins. Chelating resins are styrene-divinylbenzene polymers to which iminodiacetate groups are introduced. This functional group forms complexes with all the metallic elements except the alkali metals, with stabilities that vary with the different metals; in analytical chemistry, they are used for the separation of trace amounts of metals. Electron-exchange resins accept or donate electrons to the surrounding solution and are used in oxidation-reduction reactions; examples include polymers prepared from hydroquinone, phenol, and formaldehyde.A group of minerals that have ion-exchanging properties is the zeolites (q.v.).
* * *
Look at other dictionaries:
ion exchange resin — n an insoluble material of high molecular weight that contains either acidic groups for exchanging cations or basic groups for exchanging anions and is used in ion exchange processes and in medicine (as for reducing the sodium content of the body … Medical dictionary
ion exchange resin — ion exchange resin, a synthetic resin which has the ability to exchange ions with a solution, used in the ion exchange process … Useful english dictionary
Ion exchange resin — An ion exchange resin is an insoluble matrix (or support structure) normally in the form of small (1 2 mm diameter) beads, usually white or yellowish, fabricated from an organic polymer substrate. The material has highly developed structure of… … Wikipedia
ion-exchange resin — jonitinė derva statusas T sritis radioelektronika atitikmenys: angl. ion exchange resin vok. Ionenaustauschharz, n rus. ионообменная смола, f pranc. résine d échange ionique, f … Radioelektronikos terminų žodynas
ion-exchange resin — jonitinė derva statusas T sritis chemija apibrėžtis Sintetinis stambiamolekulis organinis jonitas. atitikmenys: angl. ion exchange resin rus. ионообменная смола … Chemijos terminų aiškinamasis žodynas
ion-exchange resin — noun : an insoluble material of high molecular weight that contains either acidic groups for exchanging cations or basic groups for exchanging anions and that may be used in medicine (as for reducing the sodium content of the body or the acidity… … Useful english dictionary
ion exchange resin — noun An insoluble matrix of small beads having a charged surface; used as an artificial zeolite in water softeners and in ion exchange chromatography … Wiktionary
ion exchange resin — noun Date: 1943 an insoluble material of high molecular weight that contains groups which can be exchanged with ions in a solution with which it is in contact … New Collegiate Dictionary
Ion-exchange resin — Ионно обменная смола … Краткий толковый словарь по полиграфии
ion-exchange resin — Смотри иониообменная смола … Энциклопедический словарь по металлургии