DF
Influent concentration, conductivity, or
radioactivity
Effluent concentration, conductivity, or radioactivity
Principles of Water Treatment
DOE-HDBK-1015/2-93
WATER TREATMENT PROCESSES
Rev. 0
CH-04
Page 13
Summary
The important information in this chapter is summarized below.
Ion Exchange Summary
Demineralize is defined as the process whereby impurities present in the
incoming fluid (water) are removed by exchanging impure ions with H and
+
OH ions resulting in the formation of pure water.
-
Ion exchange is a process used extensively in nuclear facilities to control
the purity and pH of water by removing undesirable ions and replacing
them with acceptable ones.
Mixed-bed demineralizer is a vessel containing resin that is a uniform
mixture of cation and anion resins in a specific volume ratio depending on
their specific gravities. Normally the ratio is 2 parts cation resin to 3 parts
anion resin.
Cation is an ion with a positive charge. Common cations include Ca ,
++
Mg , Fe , and H . A cation resin is one that exchanges positive ions.
++
++
+
Anion is an ion with a negative charge. Common anions include Cl , SO
,
-
-2
4
and OH . An anion resin is one that exchanges negative ions.
-
Decontamination factor (DF) is a ratio of the concentration (or activity) of
the fluid at the inlet compared to the concentration (or activity) at the
effluent, which defines the effectiveness of the ion exchange process.
Mathematically it is:
Polymers are extremely large molecules that are formed by the combination
of many molecules of one or two compounds in a repeating structure that
produces long chains.
Affinity is often used to describe the attraction between a resin and a given
ion. This affinity can be described quantitatively by experimental
determination of a parameter called the relative affinity coefficient.
