Ion Exchange Resin
for Water Dealkalization

Get in touch with an expert

Felite™ Resin Technology supplies the best resin types for dealkalization application. According to the selected dealkalization process, SAC, WAC, and SBA type-II resin types can be used. The following specially manufactured anion resins can use in dealkalization along with Felite™ strong acid cations in appropriate conditions.

Request a sample for quality evaluation?

Felite™ supplies polystyrene SAC resins in both ionic forms of Hydrogen and Sodium.
Contact the Felite™ team for the best consultation to find the best resin type for your application.

Still not finding what you’re looking for?
Or, request a sample for quality evaluation?

All You Need to Know About Water Dealkalization

Water quality expresses the chemical, physical, and biological characteristics levels concerning its targeted purposes, such as drinking, processing, or swimming.

Do you know what alkalinity is in water? Yes. It is the acid neutralizing capacity of water. Also, it is a measure of the aggregate property of water. With the known chemical composition of your water sample, alkalinity can be interpreted in terms of specific substances. Also, alkalinity is a chemical parameter that expresses the acid and base neutralizing capacity of the water body or buffering capacity of water and maintaining its stable pH level. Alkalinity presents due to hydroxide ions, carbonate ions, and bicarbonate ions in water. In most cases, bicarbonates with carbon dioxide create bulk alkalinity in natural water. Alkalinity in naturally occurring water is a function of pH water.

Alkalinity in water combined with water hardness will be a critical contaminant in industrial water-consuming processes. High water consumers have many issues in commercial sectors due to alkalinity together with hardness. It should be removed and under control to scaling & corrosion problems to reduce the operational and maintenance cost. Scaling potential is more significant in industrial heat-changing equipment due to higher heat transfer rates and high operating temperatures. Water treatment specialists introduce new technologies for water purification.

Alkalinity plays a significant role in boiler operations.

Is there any effect of alkalinity in boiler operations?

Influent alkaline water will generate hydroxide and carbon dioxide due to the breakdown of carbonates and bicarbonates in feed water during the steam generation process. Carbon dioxide vaporizes with the steam, condensates back with the steam condensation process, and forms carbonic acid. This highly acidic solution deteriorates the condensate return lines and fouling with the return crudes to the boiler. Hydroxide alkalinity supports further corrosion.

Remove alkalinity in industrial applications (Dealkalization).

Removing alkaline ions from water is called “dealkalization.” Some amine compounds can protect the condensate lines from corrosion, but it is not a cost-effective method. More amine is required with more alkaline feed water. The boiler operating process requires hardness removal and reduction of alkalinity with no removal of other solids. In the water treatment industry, process engineers prioritize membrane technology and ion exchange technology for dealkalization. In most cases softening doesn’t remove alkalinity, but demineralization does at a high cost.

Can we proceed ion exchange process for dealkalization?

Yeah, we can use the IX process in different engineering designs for dealkalizers. Various chemical processing applications use ion exchange (IX) and can be identified into three main categories.

  • Removal of ionic compounds.
  • Removal of non-ionic compounds.
  • Removal of metals in complexes.


In the first case, IX resins remove simple inorganic and organic electrolytes. There are many resin types according to the operating conditions. The main four categories are strong acid cations (SAC), weak acid cations (WAC), strong base anions (SBA), and weak base anions (WBA) resin types. Also, these four main types have gel type and macro-porous type, as well as styrene, acrylic, or formophenolic types. But, resin manufacturers develop unique resin chemical structures for high selectivity of ions. Combining two different functional groups on the same resin increases the selectivity and the exchange kinetics. The second case is frequently used for applications on organic compounds. Adsorption involves as the main mechanism. Unique resin chelates are used to remove the metal complexes.

Water treatment specialists introduced many technologies for the dealkalization process, and this article will focus on ion exchange technology. Felite™ Resin Technology has introduced different resin types for dealkalization and manufacturing specialized four resins as mentioned above.

Dealkalization is one procedure that uses IX resins to purify the water. We will further discuss FeliteTM resin types which suit the dealkalization process.

We’d love to answer any of your technical questions !

Split Stream Dealkalization

The process flow diagram shows the main summary of the split stream dealkalization process. Two strong acid resin beds are operated in two different forms in parallel; one column has SAC resins in Na+ form. The other vessel has SAC resins in H+ form. The resin bed in the sodium form act as a softener unit. The additional resin bed in hydrogen form operates as a demineralizing unit.

The influent feed water is split into two streams. One stream enters the cation resin in the sodium form column (A column), and the remainder enters the resin in the hydrogen form column (B column). The outlet water from column “A” contains 100% of influent alkalinity, and water from column “B” contains zero alkalinity and free mineral acidity (FMA). In the next step, these two streams blend. FMA in the hydrogen cation resin effluent converts sodium carbonate and bicarbonate alkalinity in the sodium cation resins effluent to carbonic acid. Refer to the following reactions for further understanding.

Carbonic acid (H2CO3) dissociation in water produces predominant species as follows.

H2CO3 ←→ H2O + CO2

Therefore, engineers set up the blended water to enter the degassifier. The countercurrent air stream will strip out carbon dioxide gas from the combined water. The final water alkalinity can be controlled by managing the percentages of each mixed water flow. The main advantage of the split stream dealkalization method is maintaining the desired alkalinity level of the final effluent water.

Strong acid cation resins have a higher operating capacity, reducing the required resin volume. FeliteTM introduces strong acid cation resins, a macro-porous type for effective treatment in dealkalizers. Using sulfuric acid as the regenerant of SAC resins is hazardous. You might be able to allocate extra capital costs and operational costs for the degassifier.

In summary, there are positive points in the split stream method, and they are;

  • Final effluent water alkalinity can control up to the desired level.
  • Alkalinity and TDS can reduce both.
  • Required resin volume is lower than type-11 due to the higher operating capacity of strong acid cations used in the split stream process.

Also, there are some downsides to this method;

  • Generally, SAC resin beds can regenerate with sulfuric acid, and the regenerant is hazardous.
  • A small caustic concentration may require stabilizing the pH level in the final treated water.
  • It is better to know the degasser’s extra operational and maintenance costs.

We’d love to answer any of your technical questions !

Chloride Anion Dealkalization

The chloride anion dealkalization process is the most prevalent in lite industrial applications commonly used for low-pressure boiler operations. A softener unit is activated before an anion unit consisting of the strong base anion (SBA), type-II resins. These resins are present in chloride form.

The following reactions occur at the softener unit to remove hardness and reduce the fouling of SBA resins. Ca2+ and Mg2+ ions are replaced by the monovalent sodium ions attached to the SAC resins in the softener unit. Then sodium ions are released into the water.

  1.  Na2-R + Ca(HCO3)2 → 2NaHCO3 + Ca-R
  2.  Na2-R + CaSO4 → Na2SO4 + Ca-R
  3.  Na2-R + CaCl2 → 2NaCl + Ca-R

Softened water enters the chloride anion dealkalizers with type-II SBA resins to reduce the alkalinity and the sulfates. Follow the ion exchange reactions shown below.

  1.  Na2SO4 + 2R – Cl → 2 NaCl + 2R –SO4
  2.  2NaHCO3 + 2R – Cl → 2 NaCl + 2R – HCO3
  3.  2Na2CO2 + 2R – Cl → 2 NaCl + 2R – HCO3
  4.  2NaNO3 + 2R – Cl → 2 NaCl + 2R – NO3

The chloride ions coming through the softener unit do not change. The salt splitting de-alkalization process has 90% efficiency in reducing the alkalinity in water without lowering the total solids. Type II SBA resins have a higher affinity to sulfate ions than alkaline ions, minimizing the resin efficiency and affecting the alkalinity leakages. The low ratio of sulfate ions to the total anions or high ratio of alkalinity to the total anions may increase the resin efficiency and decrease the alkalinity leakages.

The rapid increase of treated water’s alkalinity indicates the resin’s exhaustion and shows the regeneration requirement. Softener resins and the strong base anion type-II resin can use the brine solution to regenerate the resins as per the same procedure of softener resin regeneration. Using brine as the regenerant is safer here than in the process of the split stream.

Another point in regeneration, if caustic is used as a brine regenerant in the dealkalizing column, free CO2 in water is converted into bicarbonates or carbonates by exchanging with chloride ions. Reducing alkalinity decreases the carbon dioxide (CO2) in boiler condensate resulting in a low concentration of amine. Due to the stable TDS amount in alkaline water, there is no increase in the boiler’s concentration cycles. There can be slight increases in conductivity in boiler feed water.

Great attention is required for magnesium leakages from the softener. If magnesium hardness is higher than 1ppm, there is a chance to produce HCl after anion resin column in the condition of zero alkalinity.

MgCl2 + H2O → Mg(OH)2 + HCl

Excess softener capacity can be converted to a delikalizer, which will be a good advantage of this process. There is no initial capital cost for installing the degassifier and no operational cost.

Salt splitting de-alkalizer performs few disadvantages.

  1. The dealkalizer has low operating capacities; therefore, higher operating levels need large vessels, a large number of resins, and a high level of regenerants.
  2. The process is unable to reduce the TDS level when required.
  3. The emergency flow of hardness ions and organics through the dealkalizer may cause resin fouling.

We’d love to answer any of your technical questions !

Weak Acid Cation Dealkalization

Weak acid cation dealkalization treats raw water with both hardness and alkalinity. The influent water, either with a similar hardness level to the alkalinity level or a lesser hardness level to the alkalinity level, is the best feeding water to the WAC dealkalizers. It is a cost-effective and highly efficient system for the above condition. In the case of higher hardness than the alkalinity level, dealkalized water remains some hardness. Therefore, a softener unit must follow the WAC dealkalizers to remove the remaining hardness.

The weak acid cations are in the form of H+. WAC resins act similar to SAC resins but exchange only the cations associated with the alkalinity. The effluent water from the WAC dealkalizers enters the degassifier due to the formation of carbon dioxide by dissociation of carbonic acid. The following equation is similar to the Mg2+ and Na+ cations too.

Ca(HCO3)2 +2R-H → 2R-Ca + 2H2CO3 (R – represents the resin)

The generated carbonic acid dissociates into water and carbon dioxide. Carbon dioxide will be stripped through a countercurrent air stream within the decarbonator. Also, it removes the TDS. The softener unit will remove the remaining permanent hardness during the effluent process through the degassifier or decarbonator. Adding a small amount of caustic to maintain the desired pH level in final effluent water is better.

When the resins near exhaustion, the effluent alkalinity level is higher than influent alkalinity. At that time, the regeneration process needs to proceed. WAC resins can regenerate with sulfuric acid and the softener resins with the brine solution.

WAC dealkalizers have high operating capacities. WAC resins are capable of removing bulk hardness during dealkalization. Therefore softener has minimized its capacity. The high operating efficiency of WAC resins reduces the amount of acidic regenerant waste.

Weak acid cation dealkalization treats raw water with both hardness and alkalinity. The influent water, either with a similar hardness level to the alkalinity level or a lesser hardness level to the alkalinity level, is the best feeding water to the WAC dealkalizers. It is a cost-effective and highly efficient system for the above condition. In the case of higher hardness than the alkalinity level, dealkalized water remains some hardness. Therefore, a softener unit must follow the WAC dealkalizers to remove the remaining hardness.

The weak acid cations are in the form of H+. WAC resins act similar to SAC resins but exchange only the cations associated with the alkalinity. The effluent water from the WAC dealkalizers enters the degassifier due to the formation of carbon dioxide by dissociation of carbonic acid. The following equation is similar to the Mg2+ and Na+ cations too.

Ca(HCO3)2 +2R-H → 2R-Ca + 2H2CO3 (R – represents the resin)

The generated carbonic acid dissociates into water and carbon dioxide. Carbon dioxide will be stripped through a countercurrent air stream within the decarbonator. Also, it removes the TDS. The softener unit will remove the remaining permanent hardness during the effluent process through the degassifier or decarbonator. Adding a small amount of caustic to maintain the desired pH level in final effluent water is better.

Figure 3

When the resins near exhaustion, the effluent alkalinity level is higher than influent alkalinity. At that time, the regeneration process needs to proceed. WAC resins can regenerate with sulfuric acid and the softener resins with the brine solution.

WAC dealkalizers have high operating capacities. WAC resins are capable of removing bulk hardness during dealkalization. Therefore softener has minimized its capacity. The high operating efficiency of WAC resins reduces the amount of acidic regenerant waste.

We’d love to answer any of your technical questions !

Regeneration of Dealkalization Resin

Continuous operation of IX resin exhausts with exchange ions gradually decreases the resin efficiency. The regeneration procedure is similar to the IX resin procedures of each resin type.
In the chloride anion dealkalization, anion resin can regenerate with brine solution. It can return the anion resin to its pre-form of chloride. Adding a small amount of caustic soda to the regenerant will increase the alkalinity removal ability.
When we consider the weak acid cation dealkalization, the resin layers can regenerate with an adequately prepared sulfuric acid solution, then with a brine solution. Here, the sodium chloride brine supports the conversion resin to its initial form of Sodium ions. Using sulfuric acid as the regenerant can help the precipitation of calcium sulfate; therefore, maintaining the required acid concentration is a must. HCl acid (with common concentration 5% w/v) also can use for regeneration.

Why Choose Felite™ Ion Exchange Resin ?

With five decades of experience, Felite Resin Technology is well versed in this field. In other hand, you are dealing with the master. You can trust us with your needs and expectations.

In the past five decades, we’ve developed several ion exchange resin models as per different customers and applications required, from standard mesh to fine mesh; from industrial grade to potable water grade.

  • Only brand new and fresh resins are provided;
    1000 cu.ft per day as throughput, shorten the lead time;
  • Various mesh options for different flow rates;
  • Factory directly, no middle man;
  • Easy to work with, 24/7 available;
  • Private Label Services;

Want to know how we make doing business easier? Let’s talk.

Valuable words from our customers

We switched to Felite™ Resin Technology a couple of years ago, and things are getting better. We really appreciate the advices from them. These guys are my day savior.

Pablo Hensley - Supply Chain Coordinator

Reliable products. I would recommend no other supplier but Felite™ Resin Technology. So if you are currently looking for an Ion Exchange Resin supplier, you ought stop and talk to them.

Alex Allman - Purchasing Manager

Request A Free Quote

We'd like to work with you!

Send us a message if you have any questions or request a quote. One of our experts will reply to you within 24 hours and help to select the suitable resin you want.

Let's Start The Conversation...