DM water, or demineralized water, is water that has had its dissolved mineral salts and ions removed. This purification process results in water with very low conductivity, making it suitable for various industrial, laboratory, and medical applications.
Demineralized water is typically produced through advanced water purification technologies.
Primary Production Methods
According to standard practices and the provided reference, demineralized water is usually made by using ion exchange, electrodeionization, or membrane filtration technologies. These methods are highly effective at removing dissolved ions.
Let's briefly look at these key technologies:
Ion Exchange
This is a common method where water passes through a bed of specially manufactured resins. These resins attract and hold onto dissolved ions (like calcium, magnesium, sodium, chlorides, sulfates, etc.), replacing them with either hydrogen ions (H⁺) and hydroxyl ions (OH⁻). When H⁺ and OH⁻ combine, they form pure water (H₂O), effectively demineralizing it.
Electrodeionization (EDI)
EDI combines ion exchange resins with ion-selective membranes and an electrical field. Water flows through chambers containing resins and membranes, and an electric current drives the dissolved ions across the membranes, out of the water stream. This continuous process regenerates the resins without needing chemicals, offering a consistent supply of high-purity water.
Membrane Filtration Technologies
Certain membrane processes are also used to produce demineralized water. These technologies utilize semi-permeable membranes to separate dissolved solids, including ions, from water. While processes like reverse osmosis (RO) are primarily known for reducing total dissolved solids, they are often used as a pre-treatment step before ion exchange or EDI to improve efficiency and water quality, or can be designed to achieve high demineralization levels themselves.
Efficiency Compared to Distillation
While processes like distillation (where water is boiled and condensed, leaving dissolved contaminants behind) can purify water, technologies such as ion exchange, electrodeionization, and membrane filtration are often considered more efficient for creating ultrapure water by removing dissolved ions.
These methods offer effective ways to achieve the high level of purity required for demineralized water, catering to diverse needs across industries.
