Ion exchange process (ion exchange process) is a reversible chemical reaction between ions in the liquid phase and ions in the solid phase, when some ions in the liquid phase are more ion exchange solids prefer, they will be adsorbed by the ion exchange solids, in order to maintain the electrical neutrality of the aqueous solution, so the ion exchange solids must be released into the equivalent ions back into the solution.
An ion exchange resin is a polymer with a corresponding functional group. In general, conventional sodium ion exchange resins carry a large number of sodium ions. When the content of calcium and magnesium ions in water is high, the ion exchange resin can release sodium ions, and the functional group binds to the calcium and magnesium ions, so that the content of calcium and magnesium ions in the water is reduced and the hardness of the water decreases. Hard water becomes soft water, which is the working process of softened water equipment. When a large number of functional groups on the resin are combined with calcium and magnesium ions, the softening ability of the resin decreases, and the sodium chloride solution can be used to flow through the resin, at this time the sodium ion content in the solution is high, and the functional group will release calcium and magnesium ions and bind to the sodium ions, so that the resin will restore the exchange capacity, this process is called "regeneration".