Overview of ion exchangers

The phenomenon of ion exchange is a form of the movement of matter, and it is universally present in the movement and changes of all things
.
Around 1850, the British Thompson and Way systematically reported the exchange of calcium and magnesium ions in the soil with potassium and ammonium ions in the water, which attracted much attention
.
Later, Eichorn and others continued to study and pointed out that the reversible ion exchange and the equivalent relationship in the soil are based on the action of zeolite.
In 1903, Harms and Rumpler reported on silicon.
After the synthesis of acid aluminum salt ion exchanger, Gans first used natural and synthetic silicates for water softening and sugar purification
.
In 1933, the British Adams and Holms first used artificial methods to manufacture phenolic cation and anion exchange resins
.
In 1945, American D'Alelio published the preparation method of polystyrene type strong acid cation exchange resin and polyacrylic acid type weak acid cation exchange resin.
Later, polystyrene anion exchange resin and redox resin And chelating resins have also appeared one after another, and the application technology and its scope have also been expanding
.
In the late 1950s, various macroporous resins have also been developed.
In production and scientific research, ion exchange resins are playing an increasingly important role
.

Inorganic ion exchanger

Ion exchangers are divided into two types: inorganic and organic
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Inorganic ion exchangers are mainly divided into the following six categories: ①Aluminosilicates, including natural montmorillonite, various zeolites and various synthetic molecular sieves; ②Insoluble polyvalent metal acid salts, polyvalent metals including zirconium, Titanium, cerium, tin, etc.
, acid radicals include phosphate, pyrophosphate, antimonate, molybdate and arsenate; ③Insoluble multivalent metal hydrated oxides, such as beryllium, magnesium, aluminum, tin, silicon, thorium, titanium, Hydrous oxides of zirconium, manganese, antimony, vanadium, niobium, tungsten and molybdenum; ④ insoluble ferrocyanide, mainly silver, zinc, cadmium, tungsten, copper, cobalt, iron, titanium, vanadium, molybdenum, tungsten, uranium The ferrocyanide; ⑤ heteropoly acid salt and composite inorganic ion exchanger, which is represented by ammonium dodecanophosphomolybdate (AMP); ⑥ other types, such as certain sulfides and sulfates
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At present, the main application field of inorganic ion exchangers is the separation of radioisotopes
.
Since it has a strong selectivity, it can be used a monovalent alkali metal cation separation, containing a large amount from the Na ⁺ separation was Cs ⁺ , MoO containing from large _.
4 ^2- separated WO solution _.
4 ^2- and the like
.
The use of inorganic ion exchangers such as clinoptilolite and mordenite to selectively adsorb Pb ²⁺ , Cu ²⁺ , Zn ²⁺ , and Cd ²⁺ has a good effect on the treatment of heavy metal-containing industrial wastewater and electroplating wastewater
.