Cation Exchange

Definition - What does Cation Exchange mean?

Cation exchange refers to the electrochemical process where identical cation charges are equally exchanged between a solution like water and a solid like zeolite. This process is typically applied to soften water to reduce its corrosiveness.

It is broadly used in the following industries:

  • Metal finishing
  • Hydrometallurgy
  • Potable or industrial water
  • Food and beverage
  • Nuclear
  • Semiconductor

However, the most common application is in the field of water decontamination, softening or purification.

Corrosionpedia explains Cation Exchange

The process of cation exchange involves penetration of water via resin bead material known as exchange resins. Water ions are typically replaced with other ions that are fixed to these beads. This could result either in deionization or softening of water.

Primarily, softening is utilized as a form of pretreatment technique to decrease the hardness of water before it undergoes the process of reverse osmosis. In such cases, the softeners utilize beads that replace two ions of sodium for each magnesium or calcium ion taken from softened water.

Deionization beads replace ions of hydroxyl with anions while ions of hydrogen are exchanged for cations. The resins for cation exchange can be made up of sulfonic acid and styrene that is capable of exchanging ions of hydrogen for cations. The resins may be contained in bed exchangers through individual units for anion and cation exchange beds or may be mixed. In any case, the resin should undergo regeneration once exchange has occurred.

Cation exchange is a common practice in many industries as it offers many advantages. Primarily, it is compact and involves little cost. The chemicals involved in the process are also safer and easier to handle. Additionally, it is almost completely automated since resins are highly capable of eliminating water hardness. This can be very useful for operators in terms of attaining the desired hardness level of water that should be sustained. It is not only an effective way of producing quality water, but also a way to reduce the corrosion capabilities of water, which offers a tremendous solution for industries that rely on this process to make water less corrosive.

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