A mixed bed demineralizer is a water demineralizer in which the cation and anion resin beads are mixed together. In effect, it is equivalent to a number of two-step demineralizers in series. In a mixed bed demineralizer, more impurities are replaced by hydrogen and hydroxyl ions, and the water that is produced is extremely pure. The conductivity of this water can often be less than 0.06 microns per centimeter.
Ion Exchange can be defined as a reversible exchange of ions between a solid (resin) and a liquid containing dissolved ions. Mineral salts are comprised of cations and anions. Since demineralizer requires the removal of all ions, both the negatively charged anions and positively charged cations, minerals capable of attracting both are required. These materials are known as anion and cation exchange resins.