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Cation and Anion Exchange Resins?
What
Is the Difference Between Cation and Anion Exchange Resins?
SAMCO
Using ion exchange
resins for industrial water purification and separation can be complex,
especially for those unfamiliar with what ion exchange resins are and how they work.
If you are looking
for a general explanation of “what the differences are between cation
and anion exchange resins,” the two most-used resins in ion exchange
technology, this article simplifies the similarities and differences and
outlines some fundamental information you should know when seeking to
understand these ion exchange basics.
How cation and anion exchange resins are similar
Cation and anion
exchange resins are both small, porous, plastic beads (approximately .5 mm
diameter, which varies) that are fixed with a specific charge.
This “fixed” charge
cannot be removed and is part of the resin’s crosslinked makeup or structure.
Each resin bead
must also contain a neutralizing counterion that is able to move in and out of
the bead, which is replaced with an ion of similar charge during the process of
ion exchange (when an aqueous solution is passed through the beads and the ion
exchange occurs, removing the undesirable contaminant).
How cation and anion exchange resins are different
The main difference
between cation and anion resins is that one is positively charged (cation) and
the other is negatively charged (anion).
This makes them
useful in removing different types of contaminants (which will also vary
depending on their size and chemical composition).
Cation and anion
resin beads can be used together (mixed bed configuration) or in separate
vessels (twin bed configuration), depending on the needs of the facility and if
total removal of positively and negatively charged ions are required.
Although anion and
cation exchange resins are the main two categories of resins used in ion
exchange, there are four main types for standard water treatment that include:
·
Strong base anion
·
Weak base anion
·
Strong acid cation
·
Weak acid cation
Below is a general
overview of what each of these types of resins are:
Strong base anion resins
Strong base anion
(SBA) exchange resins are typically used for demineralization,
dealkalization, and desilication, as well as removal of total organic carbon (TOC)
or other organics depending on the type of resin.
They are available
in multiple varieties, each of which offer a unique set of benefits and
constraints, but in general, SBA resins are strong enough to remove
both strong and weak acids (including carbonic and silicic acid).
Weak base anion resins
Weak base anion
(WBA) exchange resins are often paired with SBA units for demineralization
applications as they only remove anions associated with stronger acids
(like chloride and sulfate) and will not remove weak acids (like carbon dioxide
and silica).
This can be
beneficial for facilities that wish to remove the stronger acids while leaving
the weaker behind, but commonly, WBA and SBA are often used jointly to complete
a more thorough demineralization process.
Strong acid cation resins
Strong acid cation
(SAC) exchange resins are among the most widely used resins, especially for
softening applications, as they are effective at complete removal of
hardness ions such as magnesium (Mg+) or calcium (Ca2+).
Certain varieties
of SAC resins have also been developed for applications demanding removal of
barium and radium from drinking water or other streams. SAC resins can be
damaged by oxidants and fouled by iron or manganese, so care must be taken to
avoid exposure of the resin to these materials.
Weak acid cation resins
Weak acid cation
(WAC) exchange resins remove cations associated with alkalinity (temporary
hardness) and are used for demineralization and dealkalization
applications.
Additionally, WAC
resins tend to have relatively high oxidation resistance and mechanical
durability, making them a good choice for streams containing oxidants such as
hydrogen peroxide and chlorine.
How SAMCO can help
SAMCO has over 40
years’ experience custom-designing and manufacturing ion exchange systems and
providing ion exchange resins for a range of industries and solutions, so
please feel free to reach out to us with your questions. Some of our most
innovative solutions come in the form of the various resin technologies we
offer. Our resins cab be extremely effective in the removal of
hardness, alkalinity, chloride, mercury, and organics, to name a few.
We are also the
Northeast licensed distributor of AMBERPACK™ and UPCORE™ technologies by The
Dow Chemical Company (formerly Rohm and Haas). These are two of the most
advanced ion exchange systems available today.
For more information
or to get in touch, contact us here to set up a consultation
with an engineer or request a quote. We can walk you through the
steps for developing the proper solution and realistic cost for your ion exchange treatment system and
resin needs.
To learn more about
SAMCO’s innovative technologies and services, visit our innovations page here.
Since its 1998 founding, SAMCO Technologies
has provided custom water, wastewater, process separation, and filtration solutions
to a diverse range of industries. Our individualized, project-based approach
continues to define our niche in modern industry, motivating us to deliver
comprehensive, efficient solutions to meet our customers’ unique
needs.
At
SAMCO, we anticipate the needs of industry, and respond with
forward-thinking solutions. Our focus on industrial applications began in 1987
with the founding of Northeast equipment supplier and systems servicer CS
Kimeric. Acquired from a Western New York soft water provider with over 30
years in the business, CS Kimeric was established to provide specialized service
for industrial applications. Over the course of the next decade, it became
clear that industrial clients would benefit from working with a partner capable
of delivering comprehensive, concept-to-completion solutions. In 1998, founder
and CEO Richard Posa established SAMCO as an integrated provider of design,
fabrication, startup, and maintenance services.
Today,
SAMCO serves the process water needs of clients across the nation and globe
from its headquarters in Buffalo, New York. Leveraging the collective skills of
experienced chemical, civil, environmental, electrical, mechanical and process
engineers, chemists, and skilled tradesmen, SAMCO blends a culture of teamwork,
commitment and passion to help solve your unique industrial water treatment
needs.
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