Ion exchange resins are widely used in water purification systems in country houses, cottages. This filter media became widely known and used at the end of the last century.

It is an insoluble matrix (or support structure) normally in the form of small (0.5–1 mm diameter) microbeads, usually white or yellowish, fabricated from an organic polymer substrate. If you are not introduced to this tech The beads are typically porous, providing a large surface area on and inside them. The trapping of ions occurs along with the accompanying release of other ions, and thus the process is called ion exchange. There are multiple types of ion-exchange resin. Most commercial resins are made of polystyrene sulfonate.

Now let's take a closer look at this material. From the standpoint of chemistry, ion exchangers (a scientific name is ion-exchange resins) is a high molecular weight compounds with functional groups which can exchange-react with the ions of liquid. Some resins may also participate in oxidation reactions, reduction, physical sorption (absorption of some compounds).

Resin for filter may have a different structure - gel, porous and intermediate.

Ion exchangers with gel structure doesn't have pores, and ion exchange process occurs only when the resin is in the swollen state, becomes gel-like.

The porous or macroporous structure is called so because on the surface of the resin is large number of pores that contribute to ion exchange.

Intermediate structure - the average by properties between a gel and a porous structure.

What are their essential difference? Resin for filter-gel structures has high exchange capacity, higher than the porous structure. But the ion exchange resin with pores has a better chemical and thermal resistance, it means it can hold a larger amount of impurities in any temperature of water.

Another division of ion exchange resins - by charge of the ions. If the resin is exchanging positively charged ions (cations), it is called a cation; if negatively charged (anions) - anionic. The practical difference is in their ability to exchange in water with various pH levels (level of pH). Some of the anion, for example, can "work" at a pH of 1 - 6 and the cation - at a pH greater than 7. However, all these details will know expert, who will help you to pick up a filter to purify water from a well or other source.

Produced ion exchange resin contains ions of salts (sodium or cuprous chloride) or a mixture with salts with other compounds (sodium-hydrogen, hydroxyl-chloride).
Выпускаемая ионообменная смола, как правило, содержит ионы солей (хлористая или натриевая) или смесь солей с другими соединениями (натрий-водород, гидроксил-хлорид).

Resin filters can be different, it all depends on its performance

The most important is the resin humidity. The less it is, the better. The moisture is removed from the resin before packaging in special centrifuges.

Another important indicator of the characteristics of the ion exchange resin is its capacity. It shows a number of source ions per unit of resin mass or volume. There are selected weight and volumetric capacity and, separately, - work capacity. The first two containers are standard values, they are determined in the laboratory and are indicated in the characteristics of the finished product.

Operating ion exchange capacity - is not measured in the laboratory, because it depends on so many "operatingg" parameters - the size of the resin layer, the level of contamination of the treated water, flow rate, and many other. When operating ion-exchange capacity of the resin has run its course, it will mean that the ions in it have completely exchanged with impurity ions, and you need to restore its filtering ability (operating capacity).

For what purposes ion exchange resin is used? Filters with ion exchange resins are used in water treatment systems in country houses, cottages and villas to remove hardness salts or to soften the water. In such filters the calcium and magnesium ions are replaced by harmless sodium ions, and as the regeneration liquid, which restores the working capacity of ion exchange resin, use a strong salt solution.

Filters with ion-exchange resin are used to remove iron, manganese and other elements, but the resin used therein will be more expensive because of the "universality".


Lewatit® MonoPlus S 108

Lewatit® MonoPlus S 108 is a strongly acidic, gel-type cation exchange resin in the Na-form with beads of uniform size (monodisperse) based an a styrene-divinylbenzene copolymer. Due to a special manufacturing process this resin type is extremely resistant to chemical, osmotic and mechanical stress. That leads to very low leachables even under critical conditions like higher temperatures, presence of oxidants (02, Fe-oxides) and external regeneration processes. Even at very short cycle times (one cycle = service + regeneration) the special ion exchange resin matrix leads to long life cycles in demineralization processes. The high total capacity results in high operating capacities with a very low ionic leakage and a very high regenerant utilization.

The extremely high monodispersity [uniformity coefficient: 1.05 (+/- 0.05)] and very low fines content of max. 0.1 % (< 0.4 mm) results in particularly low pressure losses paired with an efficient and cost optimized operation of demineralization plants.

**Lewatit® MonoPlus S 108 is especially suitable for:

  • demineralization of water for industrial steam generation operated with co-current or modern counter-current systems like e.g. Lewatit WS System, Lewatit Liftbed System or Lewatit Rinsebed System
  • polishing using the Lewatit Multistep System or a conventional mixed bed arrangement in combination with the following anion components: Lewatit® MonoPlus M 500 MB, Lewatit® MonoPlus M 800, Lewatit® MonoPlus M 600, Lewatit® MonoPlus MP 500, Lewatit® MonoPlus MP 800 and Lewatit® MonoPlus MP 600.

Lewatit® MonoPlus S 108 adds special features to the resin bed:

  • high flow rates during regeneration and loading
  • high operating capacity at low regenerant consumption
  • low rinse water requirement
  • homogeneous throughput of regenerants, water and solutions, resulting in a homogeneous operating zone
  • virtually linear pressure drop gradient across the entire bed depth, allowing operation with higher bed depths
  • low TOC emission and high resistance to oxidative stress
  • good separation of the components in mixed bed applications.

The special properties of this product can only be fully utilized if the technology and process used correspond the current state-of-the-art. Further advice in this matter can be obtained from Lanxess, Business Unit Ion Exchange Resis.

More in detail about MonoPlus S 108