DOWEX Ion Exchange Resins WATER CONDITIONING MANUAL

Terms, Acronyms, And Abbreviations
2 TERMS, ACRONYMS, AND ABBREVIATIONS
Table 1 lists terms commonly used in ion exchange and Table 2 lists acronyms and abbreviations.
Table 1. Terms common to ion exchange.
Term Definition
Absolute density Weight of wet resin that displaces a unit volume, expressed as grams per unit volume in
a specific ionic form.
Adsorption Attachment of charged particles to the chemically active groups on the surface and in the
pores of an ion exchange resin.
Air mixing Process of using air to mix two ion exchange materials of different densities in a water
slurry to yield a homogeneous mixed bed.
Alkalinity Amount of carbonate, bicarbonate, and hydroxide present in water. Alkalinity is
commonly expressed as “P” and “M” in parts per million (ppm) or mg/L as calcium
carbonate (CaCO3). “P” represents titration with a standard acid solution to a
phenolphthalein endpoint. “M” represents titration to a methyl orange endpoint.
Anion exchange resin A positively charged synthetic particle that can freely exchange associated anions based
on differences in the selectivities of the anions. Also referred to as anion resin.
Attrition Breakage and abrasion of resin beads occurring when the beads rub against other
beads or other solids.
Backwashing Upward flow of water through an ion exchange resin bed to remove foreign material and
reclassify the bed after exhaustion and prior to regeneration. Also used to reduce
compaction of the bed.
Base exchange Exchange of cations between a solution and cation exchange resin.
Batch operation Method of using ion exchange resins in which the resin and the solution to be treated are
mixed in a vessel, and the liquid is decanted or filtered off after equilibrium is attained.
Bed Ion exchange resin contained in a column. See Exchanger bed.
Bed depth Depth of ion exchange resin in a column.
Bed expansion Separation and rise of ion exchange resin beads in a column during backwashing.
Bed volume Volume of ion exchange material of specified ionic form contained in a column or
operating unit, usually measured as the backwashed, settled, and drained volume.
Bed volume per hour Measure of the volume flow rate through an ion exchange material contained in a column
or operating unit, expressed as BV/h, m 3 /h/m 3 , or gal/min/ft 3 .
Bed warm-up Step just prior to regenerant injection where hot dilution water is added to the resin bed
to heat the bed to the appropriate temperature. This is to enhance polymerized silica
removal.
Boiler feed water Water used in steam boilers and some industrial processes. Boiler feed water may
possibly be raw water, treated water, condensate, or mixtures, depending on the need.
Breakthrough Volume of effluent where the concentration of the exchanging ion in the effluent reaches
a predetermined limit. This point is usually the limit of the exhaustion cycle and where
the backwash cycle begins.
CADIX Computer-Aided Design of Ion eXchange systems. Computer software for designing ion
exchange resin plants using DOWEX resins.
Capacity Number of equivalents of exchangeable ion per unit volume, unit wet weight, or dry
weight of an ion exchange material in specified ionic form.
Carboxylic Term describing a specific group that imparts a weakly acidic exchange ability to some
resins.
Cation exchange resin Negatively charged synthetic particle that can freely exchange associated cations based
on differences in the selectivities of the cations. Also referred to as cation resin.
DOWEX Ion Exchange Resins 9 Water Conditioning Manual