Electrodeionization (EDI) is a process by which an electric field is used to separate ions and polar particles from aqueous liquids. The use of EDI with reverse osmosis for water treatment can replace ion-exchange resin-mixed beds, which demand offsite or onsite chemical regeneration.


Electro-ionization is a water treatment process that uses electricity to remove ions and impurities from the water! This amazing technology can provide you with clean and refreshing water straight from your tap! ED is a process that uses electric current to remove electrons from molecules.

This can be used to create a variety of amazing chemicals, including polar molecules and hydroxyl radicals!

How it works:

By running an electric current through water, electrolysis produces hydrogen gas and oxygen gas. The hydrogen gas is then collected and the oxygen gas is released back into the water.  Electrodeionization (EDI) is the process of using an electric field to remove ions and polar species from an aqueous stream.

EDI is used for reverse osmosis with a water solvent replacement to remove ion-exchange resin-propellant beds, which require on-site or off-site chemical regeneration.

EDI introduces environmentally and economically beneficial changes by eliminating resin-kind regenerative seeding agents. EDI’s continuous replenishment process effectively improves water quality by removing water fluctuations and fluctuations.

Two electrodes are on either side of several EDI filters, which are known as dilution and addressor compartments. As water flows through the EDI device power is applied.

Ion Migration

The second step of the electrodialysis process is ion migration. This differs from chemically regenerated ion exchange because EDI continuously translates ions from the resin. Conventional ion exchange resin is depleted until chemical regeneration happens.

The DC energy supplied between EDI outlets goes between the electrodes to the cathode of the anode. The electrical flow is the movement of electrons from the reduction site (cathode) to the giveaway site (anode). The negatively charged electrode is a cathode, where the reduction effect of the oxidation number occurs.

The electrode to which the electrons are taken from (that is, that oxidizes) is called the anode and is naturally positively charged. As the charge ions are withdrawn from the liquid will be attracted to a negative cathode, where electrons from the atmosphere can be attracted, or a less negative oxidation number is created.

Likewise, anions are attracted to the negative anode where electrons leave the cell or the oxidation number increases.  The anion of an anion resin bed, cation exchange membrane, and concentrate chamber attract the cathode, the positively charged ions will migrate, and the negatively charged ions will migrate.

Once the ions are in the concentrate stream, they are not able to continue their migration to the electrode as they encounter an oppositely charged ion exchange membrane that does not permit entry to the adjacent diluting chamber.

Concentrate water exits the EDI module and is most often sent directly to the drain since this is typically only 5-10 percent of the feed water.

Continuous Regeneration

The ions are taken out of the chamber and move toward the concentrate chamber during resin regeneration. Under conventional ion exchange, the resin is regenerated with hydrochloric acid (HCl), or sometimes sulphuric acid (H2SO4), by cation exchange resin.

When this is done, the massive concentration of H+ displaces the cations on the resin. An immobilized hydroxide exchange resin can be directly added to a solution of hydroxide ions. As a result, the anions dissociate from the resin and replace them.

EDI does not require acid to regenerate the cation exchange resin, nor does it require caustic chemicals to regenerate the anion resin. Instead, it takes advantage of the electrical current that is applied across the EDI module.
In the presence of the electrical field, a phenomenon known as ―water splitting‖ occurs.

The electricity causes a small percentage of water molecules to split into hydrogen and hydroxide ions which continuously regenerate the resin bed: H2O → H+ + OH-.

Three processes are occurring simultaneously:

  • The deionization process is where the water is purified by ion exchange.
  • The resin where the ions are taken out is called an ionic resin.
  • The overall process involves four stages:  The first two stages are continuous processes that take place in the same vessel.


Electro DeIonisation has several advantages over other water treatment processes, including:

  • It is a fast process, which can treat large volumes of water quickly.
  • It is a cost-effective process, which can be cheaper than other water treatment processes.
  • It does not require chemicals or filter media, which can save on maintenance costs.


ED has many applications, including environmental remediation and fuel cell development. Electrodeionization is also used for the purification of water. This type of treatment is useful in areas where high concentrations of minerals are present or in areas that do not have a reliable source of tap water.

Electrodeionization (ED) is a process that uses an electric field to break down water molecules into their component hydrogen and oxygen atoms. This technology is used in water purification and wastewater treatment, among other applications.

ED is an environmentally friendly alternative to traditional chemical water treatment methods, and it can be used to treat a wide range of water sources, including seawater and freshwater. ED can be used to treat seawater, which is composed of about 97% water.

(Note: This article is for illustrative purposes only and does not imply an endorsement of any specific product or company. It’s essential to research and evaluate options based on your specific needs and requirements.)

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