Exchange ion resins are very small plastic beads, with a diameter of about 0.6 mm. These beads are porous and contain invisible water inside the beads, measured as “humidity” or “moisture content”.
The structure of the Exchange ion resin is a polymer (like all plastics) on which a fixed ion has been permanently attached. This ion cannot be removed or displaced; it is part of the structure. To preserve the electrical neutrality of the resin, each fixed ion must be neutralised with a counterion. This counterion is mobile and can get into and out of the resin bead. Figure 1 shows schematic cation and anion exchange resin beads. The dark lines represent the polymeric skeleton of the resin bead: it is porous and contains water. The fixed ions of this cation resin are sulphonates (SO3-) that are attached to the skeleton. In this picture, the mobile ions are sodium (Na+) cations. Cation resins such as Lanlang TC008 are often delivered in the sodium form.
The anion resin bead has a very similar skeleton. The functional groups are here quaternary ammonium cations shown in the picture as N+R3; a more accurate formula would be CH2-N+-(CH3)3. The mobile ions in the bead are chloride anions (Cl-). This is also the standard delivery form for many anion resins. Each ion going into the bead has to be replaced by an ion getting out of the bead, again to preserve electrical neutrality. This is what is called ion exchange. Only ions of the same electric sign are exchanged. You cannot make a resin that can exchange cations as well as anions, because the fixed cations inside the resin beads would neutralise the fixed anions and no exchange with the outside world would be possible. Therefore you need separate cation resins and anion resins.
Lanlang manufacturer exchange ion resin for 15 years, if any needs welcome to contact us!