Exhaustion

the state of an ion exchange material in which it is no longer capable of effective function due to the depletion of the initial supply of exchangeable ions; the exhaustion point may be defined in terms of a limiting concentration of matter in the effluent, or in the case of demineralization, in terms of electrical conductivity.

Definitioner

Ion Exchange: a reversible process in which ions are released from an insoluble permanent material in exchange for other ions in a surrounding solution; the direction of the exchange depends depends on the affinities of the ion exchanger for the ions present, and the concentrations of the ions in the solution.
Ion: an atom, or group of atoms which function as a unit, and has a positive or negative electrical charge, due to the gain or loss of of one or more electrons.
Exhaustion: the state of an ion exchange material in which it is no longer capable of effective function due to the depletion of the initial supply of exchangeable ions; the exhaustion point may be defined in terms of a limiting concentration of matter in the effluent, or in the case of demineralization, in terms of electrical conductivity.
Demineralization: the removal of ionized inorganic minerals and salts (not organic materials)from a solution by a two phase ion exchange procedure, similar to deionization, and the two terms are often used interchangeably.
Conductivity: the quality or power to carry electrical current; in water, the conductivity is related to the concentration of ions capable of carrying electrical current.