CATION AND ANION EXCHANGE RESINS - What Is the Difference Between Cation and Anion Exchange Resins? - 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. 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). 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. There are four main types for standard water treatment that include.

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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.

https://www.samcotech.com/difference-cation-anion-exchange-resins/

HARD AND SOFT WATER - Hard water is any water containing an appreciable quantity of dissolved minerals. Soft water is treated water in which the only cation (positively charged ion) is sodium. The minerals in water give it a characteristic taste. Some natural mineral waters are highly sought for their flavor and the health benefits they may confer. Soap is less effective in hard water because it reacts to form the calcium or magnesium salt of the organic acid of the soap. Detergents, on the other hand, lather in both hard and soft water.

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Hard and Soft Water

Chemistry of Hard and Soft Water

by Anne Marie Helmenstine, Ph.D.

You've heard the terms "hard water" and "soft water, but do you know what they mean?

Is one type of water somehow better than the other?

What type of water do you have?

This article looks at the definitions of these terms and how they relate to water in everyday life.

Hard Water vs Soft Water

Hard water is any water containing an appreciable quantity of dissolved minerals.

Soft water is treated water in which the only cation (positively charged ion) is sodium.

The minerals in water give it a characteristic taste.

Some natural mineral waters are highly sought for their flavor and the health benefits they may confer.

Soft water, on the other hand, may taste salty and may not be suitable for drinking.

If soft water tastes bad, then why might you use a water softener?

The answer is that extremely hard water may shorten the life of plumbing and lessen the effectiveness of certain cleaning agents.

When hard water is heated, the carbonates precipitate out of solution, forming scales in pipes and tea kettles.

In addition to narrowing and potentially clogging the pipes, scales prevent efficient heat transfer, so a water heater with scales will have to use a lot of energy to give you hot water.

Soap is less effective in hard water because it reacts to form the calcium or magnesium salt of the organic acid of the soap.

These salts are insoluble and form grayish soap scum, but no cleansing lather.

Detergents, on the other hand, lather in both hard and soft water.

Calcium and magnesium salts of the detergent's organic acids form, but these salts are soluble in water.

How to Soften Water

Hard water can be softened (have its minerals removed) by treating it with lime or by passing it over an ion exchange resin.

The ion exchange resins are complex sodium salts. Water flows over the resin surface, dissolving the sodium.

The calcium, magnesium and other cations precipitate onto the resin surface. Sodium goes into the water, but the other cations stay with the resin.

Very hard water will end up tasting saltier than water that had fewer dissolved minerals.

Most of the ions have been removed in soft water, but sodium and various anions(negatively charged ions) still remain.

Water can be deionized by using a resin that replaces cations with hydrogen and anions with hydroxide.

With this type of resin, the cations stick to the resin and the hydrogen and hydroxide that are released combine to form pure water.

Anne Marie Helmenstine, Ph.D.

Ph.D. in biomedical sciences from the University of Tennessee at Knoxville - Oak Ridge National Laboratory.

Science educator with experience teaching chemistry, biology, astronomy, and physics at the high school, college, and graduate levels.

ThoughtCo and About Education chemistry expert since 2001.

Widely-published graphic artist, responsible for printable periodic tables and other illustrations used in science.

Experience

Anne Helmenstine, Ph.D. has covered chemistry for ThoughtCo and About Education since 2001, and other sciences since 2013. She taught chemistry, biology, astronomy, and physics at the high school, college, and graduate levels. She has worked as a research scientist and also abstracting and indexing diverse scientific literature for the Department of Energy.

In addition to her work as a science writer, Dr. Helmenstine currently serves as a scientific consultant, specializing in problems requiring an interdisciplinary approach. Previously, she worked as a research scientist and college professor. 

Education

Dr. Helmenstine holds a Ph.D. in biomedical sciences from the University of Tennessee at Knoxville and a B.A. in physics and mathematics with a minor in chemistry from Hastings College. In her doctoral work, Dr. Helmenstine developed ultra-sensitive chemical detection and medical diagnostic tests.

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https://www.thoughtco.com/chemistry-of-hard-and-soft-water-602182