Mixed-bed demineralizer:

A mixed-bed demineralizer is a vessel, commonly along with a volume of various cubic feet, which holds the resin.  Through physically, ion exchange resins are created in the shape of extremely small beads, known as resin beads, along with an average diameter of about 0.005 millimeters.  The wet resin has the appearance of transparent, damp, amber sand and is insoluble within water, bases, and acids.  Retention components or other suitable devices in the top and bottom have openings smaller than the diameter of the resin beads. A resin itself is a uniform combination of cation and anion resins within a specific volume ratio depending on their exact gravities.  The ratio is generally 2 category cation resin to 3 category anion resins.

In a few cases, there might be chemical bonds formed among individual chain molecules at several points along the chain. Like polymers are said to be cross-connected.  This category of polymer constitutes the general structure of ion exchange resins.  Within particular, cross-linked polystyrene is the polymer generally used in ion exchange resins. Therefore, chemical treatment of polystyrene is needed to provide it ion exchange capability, and this treatment varies depending on whether the last product is to be an anion resin or a cation resin.