An ion-exchange resin or ion-exchange polymer is an insoluble matrix (or support structure) normally in the form of small (1–2 mm diameter) beads, usually white or yellowish, fabricated from an organic polymer substrate. The material has highly developed structure of pores on the surface of which are sites with easily trapped and released ions. The trapping of ions takes place only with simultaneous releasing of other ions; thus the process is called ion-exchange. There are multiple different types of ion-exchange resin which are fabricated to selectively prefer one or several different types of ions.

Ion exchange resin beads
Ion-exchange resins are widely used in different separation, purification, and decontamination processes. The most common examples are water softening and water purification. In many cases ion-exchange resins were introduced in such processes as a more flexible alternative to the use of natural or artificial zeolites.
Most typical ion-exchange resins are based on cross linked polystyrene. The required active groups can be introduced after polymerization, or substituted monomers can be used. For example, the cross linking is often achieved by adding 0.5-25% of divinylbenzene to styrene at the polymerization process. Non-cross linked polymers are used only rarely because they are less stable. Cross linking decreases ion- exchange capacity of the resin and prolongs the time needed to accomplish the ion exchange processes. Particle size also influences the resin parameters; smaller particles have larger outer surface, but cause larger head loss in the column processes.
Besides being made as bead-shaped materials, ion exchange resins are produced as membranes. The membranes are made of highly cross-linked ion exchange resins that allow passage of ions, but not of water, are used for electro dialysis.
There are four main types differing in their functional groups:

• strongly acidic (typically, sulfonic acid groups, e.g. sodium polystyrene sulfonate or polyAMPS)
• strongly basic, (quaternary amino groups, for example, trimethylammonium groups, e.g. polyAPTAC)
• weakly acidic (mostly, carboxylic acid groups)
• weakly basic (primary, secondary, and/or ternary amino groups, e.g. polyethylene amine)

There are also specialized types:

• chelating resins (iminodiacetic acid, thiourea, and many others)

MIXED BED:
Industrial Mixed Bed Deionizers are designed to produce high purity treated water required by the industries. These deionizers can be used as polishing units after two bed deionisers or directly, to obtain high purity water. Mixed bed deionisers are single-column units, filled with strongly acidic cation and strongly basic anion exchange resins mixed evenly. Dissolved solids in the water are thus removed, producing water of a very high quality - conforming to IP specifications of purified water. The treated water, however, is not free from bacteria and pyrogen

Advantages

- Easy to install.

- Simple to operate
.
- Complete with regeneration equipment and control
.
- Produce deionised water of very high purity, conforming to IP specifications

Specifications

- Two mild steel pressure vessels internally linedwith rubber, provided with internal fittings and initial charge of cation and anion exchangeresins.

- One set of regeneration equipment including hydraulic ejectors, acid and alkali tanks.

- One set of frontal pipework and valves.

- One orifice board to indicate regeneration flows.
-One dial-type electrical conductivity meter tomonitor treated water quality.

- Two pressure gauges

Optional

- One motor-driven air blower of adequate capacity to mix the ion exchange after regeneration.

- Output between regenrations can be enhanced with customer specific design

CATION AND ANION BED

Industrial Two Bed Up flow     and down flow Deionisers type Cation and Anion bed  are available in a wide range with maximum flow rates from 1.0 to 150 m3/h. as standard products These deionisers comprise two mild steel rubberlined pressure vessels filled with strongly acidic cation exchange resin and strongly basic anion exchange resin. They are available in a range of diameters. The modular construction permits flexibility in the selection of cation and anion units
to cater to different types of raw water. Degasser modules for the range of CA units are also available. These are useful for raw waters containing a significant amount of alkalinity.

Advantages

- Easy to install.

- Simple to operate
.
- Complete with regeneration equipment and control

Specifications

- Two mild steel pressure vessels internally lined with rubber, provided with internal fittings and initial charge of cation and anion exchange resins.

- One set of regeneration equipment including hydraulic ejectors, acid and alkali tanks.

- One set of frontal pipe work and valves.

- One mild steel base frame for mounting cation and anion units .

- One conductivity meter to monitor treated water quality.