ion exchanger are loaded with substances that dissolve in water exchange ions for other ions of the same charge, most of which are bound in resins.
Thus, in the water dissolved calcium ions for Sodium ions are exchanged. This prevents for example the precipitation of calcium carbonate (lime scale ugly) in the dishwasher.
Such ion exchangers are also used to de-scale hard to drinking water. The disadvantage of this ion exchanger is in the regeneration of the exchange resins. This is done according to the type of salt (dishwasher) or with acids or bases with a cation or anion exchanger.
In the aquarium makes use of this method has long advantage with so-called demineralizer or Teilentsalzer. be
In a demineralizer first exchanged into a cation exchanger, the cations and then in an anion, the anions. The result is in the ideal case, pure water.
For example, sodium chloride = NaCl, the cation exchanger, the cation exchange initially Na + against hydrogen H + HCl = hydrochloric arises. The anion exchange
now the anion Cl - against OH - arises H-OH = H2O = water.
This water can harden with tap water or saline to the desired values, and so set his aquarium water efficiently.
Teilentsalzer: If the carbonate hardness (KH), a large part of total hardness (GH), about 80% or more, sufficient to remove the carbonate in order to get the water soft. We therefore remove only part of the salts. For this one uses a weakly acidic cation exchanger, which removes only the carbonate hardness.
you used to do only a weak acid cation exchanger, it must be removed from the water before use in the aquarium, the carbonic acid. Example: Ca + + (HCO 3 - ) 2 the divalent calcium is exchanged for 2 H-ion is formed carbonic acid H 2 CO 3
Further applications of the partial desalination are neutral exchanger, for example, the nitrate or phosphate removed.
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