Electrodeionization (EDI)

Electrodeionization (EDI) isa continuous, chemical-free water purification process that uses a combination of ion exchange membranes, ion exchange resin, and a DC electric field to produce high-purity deionized water.By electrically driving ions toward selective membranes and concentrating them into a waste stream, while simultaneously regenerating the resin using water splitting, EDI eliminates the need for traditional chemical regeneration, offering a sustainable and efficient method for water demineralization and polishing.

How Electrodeionization Works

Ion Migration:

An electric field, generated by electrodes, drives dissolved ions through the water.

Membrane Separation:

Ion exchange membranes separate the water into distinct compartments.

Concentration:

Cations (positively charged ions) move toward the cathode (negative electrode), and anions (negatively charged ions) move toward the anode (positive electrode).

Concentrate and Dilute Channels:

Ions are directed to concentrate in separate channels, where they are flushed out as a reject stream, while the remaining water in the dilute channels becomes deionized.

Resin Regeneration:

Ion exchange resin particles are interspersed within the dilute channels, which lowers the electrical resistance and conducts ions to the membranes.At a certain voltage, water molecules split into H+ and OH- ions, which are then used to continuously regenerate the resins, a process known aswater splitting.

Key Benefits

Chemical-Free:Eliminates the need for harsh chemicals for regeneration, reducing costs and environmental impact.

Continuous Operation:Provides a constant supply of purified water.

High Purity:Produces high-quality deionized water with low conductivity levels.

Compact Design:EDI systems are compact and space-saving.

Self-Regenerating:The system regenerates itself, extending the life of the ion exchange resins.

Applications

Industrial Processes:Widely used in pharmaceutical, food, and chemical industries for high-purity water production.

Water Polishing:Often used afterReverse Osmosis (RO)to further purify water.

Desalination:Can be used for desalinating water and removing heavy metals.