Ion Exchange Equipment Selection GuideIon Exchange Equipment Selection Guide

Image Credit: Cleaver-Brooks | Watts

 

Ion exchange equipment is used to adjust the ionic content of water. Ions are atoms, groups of atoms, or compounds which are electrically charged as a result of the loss of electrons (cations) or the gain of electrons (anions).

 

Types

There are two basic types of ion exchange equipment: water softeners and deionizing systems.

  • Water softeners replace calcium, iron, magnesium and other metallic ions with sodium ions. They treat “hard water” and prevent the accumulation of scale in industrial boilers and pipes.
  • Deionization (DI) systems replace mineral content with oxygen and hydroxyl groups.

Most water softeners and deionization equipment include manual or automatic backwash systems. Automatic systems flush the exchange medium based on parameters such as time, volumetric operation, or chemical sensing. Because ion exchange equipment often runs discontinuously, continuous flow rate is an important specification to consider when selecting ion exchange equipment. Efficient system designs account for low-flow conditions as well as periods of peak flow periods.    

 

Applications

There are many applications for ion exchange equipment including recovery, removal, and ionic containment.

Recovery

  • Some devices and systems are used to recover copper, nickel, cobalt and other precious or heavy metals from water-based or solvent-based mixtures.

Removal

  • Products are used to remove nitrates or process organic materials.
  • Sucrose processing facilities uses ion exchange resins to soften feed streams and remove sugar from molasses.
  • Factories use ion exchange equipment to remove dissolved alkaline solids that can impede machine performance or reduce system life.
  • Ion exchange demineralization is a two-step process that involves treatment with both cation and anion exchange resins. The net effect is the removal of electrolytes and a yield of purified water.
  • Condensate polishing reduces particulate matter and dissolved contaminants in condensates from utility power plants.
  • Ion exchange equipment that captures trace amounts of radioactive materials or nuclides is also available.

  • Water softening and water purification systems are used to remove acids, alkalis, salts, or mixtures from anionic or slightly ionized substances. Ultra pure water is used in the fabrication of semiconductors and printed circuit boards. Residential ion exchange equipment is designed for single-family homes or high density facilities such as apartments or condominiums that supply water for drinking and bathing.

Ionic Containment

  • Ion exchange equipment is also used in industrial applications where ionic contamination can reduce quality and limit performance. Examples include automotive painting, automotive finishing, and electronic component assembly.

Regulated, Certified, or Approved Standards

Selecting ion exchange equipment requires an understanding of market requirements. Products that are designed for food processing, medical, or sanitary applications are often regulated, certified, or approved by government or industry. Typically, these products meet high-purity standards for analytical testing. Standards for testing, operating, or installing ion exchange equipment are also available.

 

ASTM D4548 - Standard test method for anion-cation balance of mixed bed ion-exchange resins.

NSF 61 - Standard sets health effects criteria for drinking water system components.

 

Resources

Drinking Water Treatment: Water Softening (Ion Exchange)

Ion Exchange