Ion exchange resin
Overview
 
An ion-exchange resin or ion-exchange polymer 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
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...

 substrate. The material has highly developed structure of pores on the surface of which are sites with easily trapped and released ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...

s. The trapping of ions takes place only with simultaneous releasing of other ions; thus the process is called ion-exchange.
Encyclopedia
An ion-exchange resin or ion-exchange polymer 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
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...

 substrate. The material has highly developed structure of pores on the surface of which are sites with easily trapped and released ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...

s. The trapping of ions takes place only with simultaneous releasing of other ions; thus the process is called ion-exchange. There are multiple different types of ion-exchange resin which are fabricated to selectively prefer one or several different types of ions.

Ion-exchange resins are widely used in different separation, purification, and decontamination processes. The most common examples are water softening
Water softening
Water softening is the reduction of the concentration of calcium, magnesium, and certain other metal cations in hard water. These "hardness ions" can cause a variety of undesired effects including interfering with the action of soaps, the build up of limescale, which can foul plumbing, and...

 and water purification
Water purification
Water purification is the process of removing undesirable chemicals, materials, and biological contaminants from contaminated water. The goal is to produce water fit for a specific purpose...

. In many cases ion-exchange resins were introduced in such processes as a more flexible alternative to the use of natural or artificial zeolite
Zeolite
Zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents. The term zeolite was originally coined in 1756 by Swedish mineralogist Axel Fredrik Cronstedt, who observed that upon rapidly heating the material stilbite, it produced large amounts of steam from water that...

s.

Most typical ion-exchange resins are based on crosslinked
Cross-link
Cross-links are bonds that link one polymer chain to another. They can be covalent bonds or ionic bonds. "Polymer chains" can refer to synthetic polymers or natural polymers . When the term "cross-linking" is used in the synthetic polymer science field, it usually refers to the use of...

 polystyrene
Polystyrene
Polystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...

. The required active groups can be introduced after polymerization, or substituted monomers can be used. For example, the crosslinking is often achieved by adding 0.5-25% of divinylbenzene
Divinylbenzene
Divinylbenzene consists of a benzene ring bonded to two vinyl groups. It is related to styrene by the addition of a second vinyl group. Divinylbenzene, as it is usually encountered, is a 2:1 mixture of m- and p-divinylbenzene, containing also the corresponding ethylvinylbenzene isomers. It is...

 to styrene at the polymerization process. Non-crosslinked polymers are used only rarely because they are less stable. Crosslinking decreases ion- exchange capacity of the resin and prolongs the time needed to accomplish the ion exchange processes. Particle size also influences the resin parameters; smaller particles have larger outer surface, but cause larger head loss in the column processes.

Besides being made as bead-shaped materials, ion exchange resins are produced as membranes. The membranes are made of highly cross-linked ion exchange resins that allow passage of ions, but not of water, are used for electrodialysis
Electrodialysis
Electrodialysis is used to transport salt ions from one solution through ion-exchange membranes to another solution under the influence of an applied electric potential difference. This is done in a configuration called an electrodialysis cell...

.

There are four main types differing in their functional group
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...

s:
  • strongly acidic (typically, sulfonic acid
    Sulfonic acid
    Sulfonic acid usually refers to a member of the class of organosulfur compounds with the general formula RS2–OH, where R is an alkyl or aryl. The formal part of acid, HS2–OH, are formally derivatives of the "parent" inorganic compound with the formula HSO2.-Preparation:Sulfonic acid is...

     groups, e.g. sodium polystyrene sulfonate
    Sodium polystyrene sulfonate
    Sodium polystyrene sulfonate is a type of polymer and ionomer based on polystyrene. It is the sodium salt of polystyrene sulfonic acid.-Chemical properties:...

     or polyAMPS
    PolyAMPS
    PolyAMPS, or poly, is an organic polymer. It is water-soluble, forms gels when cross linked, and acts as a strong anionic polyelectrolyte. It can be used for ion exchange resins. It can form hydrogels....

    )
  • strongly basic, (quaternary amino groups, for example, trimethylammonium groups, e.g. polyAPTAC
    PolyAPTAC
    PolyAPTAC, or poly , is an organic polymer. It is water-soluble, forms gels when cross linked, and acts as a cationic polyelectrolyte. It can be used for ion exchange resins. It can form hydrogels....

    )
  • weakly acidic (mostly, carboxylic acid
    Carboxylic acid
    Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...

     groups)
  • weakly basic (primary, secondary, and/or ternary amino groups, e.g. polyethylene amine
    Polyethylene amine
    Polyethylene amine is a polymer of aziridine with the molecular formula n. It is a structural analogue of polyethylene glycol with -NH- in place of oxygen atoms. It is produced by the polymerization of aziridine....

    )


There are also specialised types:
  • chelating resins (iminodiacetic acid
    Iminodiacetic acid
    Iminodiacetic acid, HN2, often abbreviated to IDA, is an dicarboxylic acid amine. The iminodiacetate anion can act as a tridentate ligand to form a metal complex with two, fused, five membered chelate rings...

    , thiourea
    Thiourea
    Thiourea is an organosulfur compound of with the formula SC2 . It is structurally similar to urea, except that the oxygen atom is replaced by a sulfur atom, but the properties of urea and thiourea differ significantly. Thiourea is a reagent in organic synthesis. "Thioureas" refers to a broad...

    , and many others)

Water softening


In this application, ion-exchange resins are used to replace the magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...

 and calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...

 ions found in hard water
Hard water
Hard water is water that has high mineral content . Hard water has high concentrations of Ca2+ and Mg2+ ions. Hard water is generally not harmful to one's health but can pose serious problems in industrial settings, where water hardness is monitored to avoid costly breakdowns in boilers, cooling...

 with sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

 ions. When the resin is fresh, it contains sodium ions at its active sites. When in contact with a solution containing magnesium and calcium ions (but a low concentration of sodium ions), the magnesium and calcium ions preferentially migrate out of solution to the active sites on the resin, being replaced in solution by sodium ions. This process reaches equilibrium with a much lower concentration of magnesium and calcium ions in solution than was started with.

The resin can be recharged by washing it with a solution containing a high concentration of sodium ions (e.g. it has large amounts of common salt
Sodium chloride
Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...

 (NaCl) dissolved in it). The calcium and magnesium ions migrate off the resin, being replaced by sodium ions from the solution until a new equilibrium is reached.

This is the method of operation used in dishwasher
Dishwasher
A dishwasher is a mechanical device for cleaning dishes and eating utensils. Dishwashers can be found in restaurants and private homes.Unlike manual dishwashing, which relies largely on physical scrubbing to remove soiling, the mechanical dishwasher cleans by spraying hot water, typically between ...

s that require the use of 'dishwasher salt
Dishwasher salt
Dishwasher salt is a particular grade of crystalline sodium chloride intended for use in dishwashers. Dishwasher salt is used for the same purpose as water softener salt, namely to regenerate ion exchange resins used to remove the hardness ions calcium and magnesium from water...

'. The salt is used to recharge an ion-exchange resin which itself is used to soften the water so that limescale
Limescale
Limescale is the hard, off-white, chalky deposit found in kettles, hot-water boilers and the inside of inadequately maintained hot-water central heating systems...

 deposits are not left on the cooking and eating utensils being washed.

Water purification

In this application, ion-exchange resins are used to remove poison
Poison
In the context of biology, poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism....

ous (e.g. copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

) and heavy metal (e.g. lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...

 or cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...

) ions from solution, replacing them with more innocuous ions, such as sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

 and potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...

.

Few ion-exchange resins remove chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

 or organic contaminants from water - this is usually done by using an activated charcoal filter mixed in with the resin. There are some ion-exchange resins that do remove organic ions, such as MIEX (magnetic ion-exchange) resins. Domestic water purification resin is not usually recharged - the resin is discarded when it can no longer be used.

Production of high purity water

Water of highest purity is required for electronics, scientific experiments, production of superconductors, and nuclear industry, among others. Such water is produced using ion-exchange processes or combinations of membrane and ion-exchange methods. Cations are replaced with hydrogen ions using cation-exchange resins; anions are replaced with hydroxyls using anion-exchange resins. The hydrogen ions and hydroxyls recombine producing water molecules. Thus, no ions remain in the produced water. The purification process is usually performed in several steps with "mixed bed ion-exchange columns" at the end of the technological chain.

Ion-exchange in metal separation

Ion-exchange processes are used to separate and purify metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

s, including separating uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...

 from plutonium
Plutonium
Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...

 and other actinide
Actinide
The actinide or actinoid series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium.The actinide series derives its name from the group 3 element actinium...

s, including thorium
Thorium
Thorium is a natural radioactive chemical element with the symbol Th and atomic number 90. It was discovered in 1828 and named after Thor, the Norse god of thunder....

; and lanthanum
Lanthanum
Lanthanum is a chemical element with the symbol La and atomic number 57.Lanthanum is a silvery white metallic element that belongs to group 3 of the periodic table and is the first element of the lanthanide series. It is found in some rare-earth minerals, usually in combination with cerium and...

, neodymium
Neodymium
Neodymium is a chemical element with the symbol Nd and atomic number 60. It is a soft silvery metal that tarnishes in air. Neodymium was discovered in 1885 by the Austrian chemist Carl Auer von Welsbach. It is present in significant quantities in the ore minerals monazite and bastnäsite...

, ytterbium
Ytterbium
Ytterbium is a chemical element with the symbol Yb and atomic number 70. A soft silvery metallic element, ytterbium is a rare earth element of the lanthanide series and is found in the minerals gadolinite, monazite, and xenotime. The element is sometimes associated with yttrium or other related...

, samarium
Samarium
Samarium is a chemical element with the symbol Sm, atomic number 62 and atomic weight 150.36. It is a moderately hard silvery metal which readily oxidizes in air. Being a typical member of the lanthanide series, samarium usually assumes the oxidation state +3...

, lutetium, from each other and the other lanthanide
Lanthanide
The lanthanide or lanthanoid series comprises the fifteen metallic chemical elements with atomic numbers 57 through 71, from lanthanum through lutetium...

s. There are two series of rare earth
Rare earth element
As defined by IUPAC, rare earth elements or rare earth metals are a set of seventeen chemical elements in the periodic table, specifically the fifteen lanthanides plus scandium and yttrium...

 metals, the lanthanides and the actinides. Members of each family have very similar chemical and physical properties. Ion-exchange was for many years the only practical way to separate the rare earths in large quantities. This application was developed in the 1940's by Frank Spedding
Frank Spedding
Frank Harold Spedding was a Canadian chemist who led a group of chemists at Ames Laboratory which developed an efficient process for obtaining high purity uranium from uranium halides. The general technique is known as the Thermite process, or more specifically, the Ames process...

. Subsequently, solvent extraction has mostly supplanted use of ion exchange resins except for the highest purity products.

A very important case is the PUREX
PUREX
PUREX is an acronym standing for Plutonium - URanium EXtraction — de facto standard aqueous nuclear reprocessing method for the recovery of uranium and plutonium from used nuclear fuel. It is based on liquid-liquid extraction ion-exchange.The PUREX process was invented by Herbert H. Anderson and...

 process (plutonium-uranium extraction process) which is used to separate the plutonium
Plutonium
Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...

 and the uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...

 from the spent fuel products from a nuclear reactor
Nuclear reactor
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...

, and to be able to dispose of the waste products. Then, the plutonium and uranium are available for making nuclear-energy materials, such as new reactor fuel and nuclear weapon
Nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...

s.

The ion-exchange process is also used to separate other sets of very similar chemical elements, such as zirconium
Zirconium
Zirconium is a chemical element with the symbol Zr and atomic number 40. The name of zirconium is taken from the mineral zircon. Its atomic mass is 91.224. It is a lustrous, grey-white, strong transition metal that resembles titanium...

 and hafnium
Hafnium
Hafnium is a chemical element with the symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869. Hafnium was the penultimate stable...

, which incidentally is also very important for the nuclear industry. Zirconium is practically transparent to free neutrons, used in building reactors, but hafnium is a very strong absorber of neutrons, used in reactor control rod
Control rod
A control rod is a rod made of chemical elements capable of absorbing many neutrons without fissioning themselves. They are used in nuclear reactors to control the rate of fission of uranium and plutonium...

s.

Catalysis

In chemistry
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

 ion-exchange resins are known to catalyze
Catalysis
Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. A catalyst may participate in multiple chemical transformations....

 organic reaction
Organic reaction
Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, photochemical reactions and redox reactions. In organic synthesis,...

s. See for instance self-condensation
Self-condensation
Self-condensation is an organic reaction in which a chemical compound containing a carbonyl group acts both as the electrophile and the nucleophile in an aldol condensation...

.

Juice Purification

Ion-exchange resins are used in the manufacture of fruit juices such as orange juice where they are used to remove bitter tasting components and so improve the flavor. This allows poorer tasting fruit sources to be used for juice production.

Sugar Manufacturing

Ion-exchange resins are used in the manufacturing of sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...

 from various sources. They are used to help convert one type of sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...

 into another type of sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...

, and to decolorize and purify sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...

 syrups.

Pharmaceuticals

Ion-exchange resins are used in the manufacturing of pharmaceuticals, not only for catalyzing
Catalysis
Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. A catalyst may participate in multiple chemical transformations....

 certain reactions but also for isolating and purifying pharmaceutical active ingredient
Active ingredient
An active ingredient is the substance of a pharmaceutical drug or a pharmaceutical ingredient and bulk active in medicine; in pesticide formulations active substance may be used. Some medications and pesticide products may contain more than one active ingredient...

s.
Three ion-exchange resins, sodium polystyrene sulfonate
Sodium polystyrene sulfonate
Sodium polystyrene sulfonate is a type of polymer and ionomer based on polystyrene. It is the sodium salt of polystyrene sulfonic acid.-Chemical properties:...

, colestipol
Colestipol
Colestipol is a bile acid sequestrant.It works in the gut trapping bile salts, and preventing them from being reabsorbed.This leads todecreased enterohepatic recirculation of bile salts,increased synthesis of new bile salts by the liver,...

, and cholestyramine
Cholestyramine
Cholestyramine or colestyramine is a bile acid sequestrant, which binds bile in the gastrointestinal tract to prevent its reabsorption. It is a strong ion exchange resin, which means that it can exchange its chloride anions with anionic bile acids in the gastrointestinal tract and bind them...

, are used as active ingredient
Active ingredient
An active ingredient is the substance of a pharmaceutical drug or a pharmaceutical ingredient and bulk active in medicine; in pesticide formulations active substance may be used. Some medications and pesticide products may contain more than one active ingredient...

s. Sodium polystyrene sulfonate
Sodium polystyrene sulfonate
Sodium polystyrene sulfonate is a type of polymer and ionomer based on polystyrene. It is the sodium salt of polystyrene sulfonic acid.-Chemical properties:...

 is a strongly acidic ion-exchange resin and is used to treat hyperkalemia
Hyperkalemia
Hyperkalemia refers to the condition in which the concentration of the electrolyte potassium in the blood is elevated...

. Colestipol is a weakly basic ion-exchange resin and is used to treat hypercholesterolemia
Hypercholesterolemia
Hypercholesterolemia is the presence of high levels of cholesterol in the blood. It is not a disease but a metabolic derangement that can be caused by many diseases, notably cardiovascular disease...

. Cholestyramine
Cholestyramine
Cholestyramine or colestyramine is a bile acid sequestrant, which binds bile in the gastrointestinal tract to prevent its reabsorption. It is a strong ion exchange resin, which means that it can exchange its chloride anions with anionic bile acids in the gastrointestinal tract and bind them...

 is a strongly basic ion-exchange resin and is also used to treat hypercholesterolemia
Hypercholesterolemia
Hypercholesterolemia is the presence of high levels of cholesterol in the blood. It is not a disease but a metabolic derangement that can be caused by many diseases, notably cardiovascular disease...

. Colestipol and cholestyramine
Cholestyramine
Cholestyramine or colestyramine is a bile acid sequestrant, which binds bile in the gastrointestinal tract to prevent its reabsorption. It is a strong ion exchange resin, which means that it can exchange its chloride anions with anionic bile acids in the gastrointestinal tract and bind them...

 are known as bile acid sequestrant
Bile acid sequestrant
The bile acid sequestrants are a group of medications used to bind certain components of bile in the gastrointestinal tract. They disrupt the enterohepatic circulation of bile acids by sequestering them and preventing their reabsorption from the gut. In general, they are classified as hypolipidemic...

s.

Ion-exchange resins are also used as excipient
Excipient
An excipient is generally a pharmacologically inactive substance used as a carrier for the active ingredients of a medication. In many cases, an "active" substance may not be easily administered and absorbed by the human body; in such cases the substance in question may be dissolved into or...

s in pharmaceutical formulations such as tablets, capsules, and suspensions. In these uses the ion-exchange resin can have several different functions, including taste-masking, extended release, tablet disintegration, and improving the chemical stability of the active ingredient
Active ingredient
An active ingredient is the substance of a pharmaceutical drug or a pharmaceutical ingredient and bulk active in medicine; in pesticide formulations active substance may be used. Some medications and pesticide products may contain more than one active ingredient...

s.

Sources

  • http://www.remco.com/ix.htm
  • http://www.dow.com/liquidseps/service/ix_techinfo.htm
  • F. Helfferich, Ion Exchange, McGraw Hill, New York, 1962 (Bible of the subject).
  • Ion Exchangers (K. Dorfner, ed.), Walter de Gruyter, Berlin, 1991.
  • C. E. Harland, Ion exchange: Theory and Practice, The Royal Society of Chemistry, Cambridge, 1994.
  • Ion exchange (D. Muraviev, V. Gorshkov, A. Warshawsky), M. Dekker, New York, 2000.
  • A. A. Zagorodni, Ion Exchange Materials: Properties and Applications, Elsevier, Amsterdam, 2006.
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