Ion-exchange resins

Dowex™ HCR-S/S Marathon C cation exchange resin 25 L

Artnumber: MARCNA
Article: MARCNA

Dowex™ Marathon™ C strong acid cation exchange resin is a uniform particle size and gel type resin designed by Dow Chemical Corporation (USA) for application in domestic, commercial and industrial water softening systems.

The resin’s distinctive feature is represented by the uniform distribution of its beads according to their sizes to provide excellent kinetic behavior. It exhibits good physical, chemical and thermal stability.

Key advantages:

  • uniform size beads exercise good kinetic behavior, leading to longer filter runs

  • uniformity of distribution of the beads according to sizes provides a better quality of purified water compared to standard polydisperse resins

  • kinetic acceleration of ion exchange increases regeneration efficiency and dynamic exchange capacity

  • low volume of regenerating solution and wastewater

  • effective operation for more than 5 years

Technical characteristics of the media




Functional group

Dowex™ Marathon™ C

Strong acid cation

Styrene-DVB, gel

Sulfonic acid

Ionic form during delivery


Total exchange capacity, eq/L (min.)


Moisture content, %


Uniformity coefficient, max.


Average size of the bead, µm


Number of uncracked beads, % (min.)


Beads density, g/mL


Bulk weight, g/L


Recommended operational conditions

  • Maximum operating temperature: 120 °C

  • pH range: 0...14

  • Bed depth, min.: 800 mm

  • Flow rates:

    • Service/fast rinse: 5...60 m/h

    • Co-current regeneration/displacement rinse: 1...10 m/h

    • Counter-current regeneration/displacement rinse: 5...20 m/h

  • Total rinse water consumption: 2...5 bed volumes

  • Regenerant: 8...12% NaCl

  • Salt consumption for regeneration: 100...150 g/L

During filtration of water through the cation exchange resin the hardness ions Ca2+ and Mg2+ are replaced by Na+ ions.

The replacement of calcium and magnesium ions by sodium ion prevents scale formation on the heating surfaces of boilers and heat exchangers. As water passes through the cation exchange resin, a number of sodium ions able to perform the exchange decreases, and a number of calcium and magnesium ions retained on the resin increases, so the cation exchange resin is being exhausted. That is why it should be regenerated by passing the solution of sodium chloride through the cation exchange layer, which will result in restoration of the resin’s exchange capability.