Application of Softening Resin in Water Treatment

Water treatment resins are classified into cationic resins and anionic resins. Cationic resins are subdivided into sodium and hydrogen resins. Sodium resins exchange calcium and magnesium ions into sodium ions, which soften water. This process is called cation exchange resin water softening. Hydrogen resin is the ion exchange of calcium and magnesium in water into hydrogen ion to soften water. Anion resin contains replaceable hydroxide ion, which can replace acid ion in water. At the same time, water can be changed into pure water by using anion resin and hydrogen cation resin.

Ion exchange in the water treatment industry is the reaction of equal charge molar quantity between ions in water and ions on ion exchange resin.

Cationic resins contain a large number of strong acidic groups, such as sulfonic acid SO₄²⁻, which is easy to dissociate H+, so they are strongly acidic. After resin dissociation, the negative groups contained in the bulk, such as SO₄²⁻, can adsorb other cations in the solution. These two reactions make H + in resin exchange with cations in solution. Strong acidic resin has strong dissociation ability and can dissociate and produce ion exchange in acidic or alkaline solution. After a period of time, the resin should be regenerated, that is, the ion exchange reaction is carried out in the opposite direction with chemicals so that the functional groups of the resin can be restored to their original state for reuse. For example, the cationic resin mentioned above is regenerated with a strong acid, at which time the resin releases the adsorbed cations and then combines with H + to recover the original composition. This technology is widely used in cation exchange resin water softening.