Special salt for softened water（Regeneration agent for ion exchange resin）


Special resin for softened water (including ordinary resin and food grade resin)
1、 Working principle
A water softener is specifically designed to remove calcium and magnesium ions from water, as well as algae and suspended solids, making the treated water soft and clear.
When raw water containing hardness ions passes through the resin layer inside the water softener, calcium (Ca2+) and magnesium (Mg2+) ions in the water are exchanged and adsorbed by the resin, while sodium (Na2+) ions are released with equal mass. The water flowing out of the water softener is softened water with hardness ions removed. The exchange process is as follows:
2RNa + Ca2+ = R2Ca + 2Na+
2RNa + Mg2+ = R2Mg + 2Na+
After passing through the sodium ion exchanger, Ca+and Mg+in the water are replaced with Na+.
After the sodium ion exchange resin fails, regeneration treatment is necessary to restore its exchange capacity. Regenerators are affordable and widely available. The salt solution. The regeneration process reaction is as follows:
R2Ca + 2NaCl = 2RNa + CaCl2
R2Mg + 2NaCl = 2RNa + MgCl2
After the above processing, the regeneration process is to rinse the resin layer with saline solution in the salt box, replace the hardness ions on the resin, and discharge it out of the tank with the regeneration waste liquid. The resin then recovers its softening and exchange ability. The specific workflow is as follows:
When water flows through the resin layer, the ion exchange resin can release sodium ions, and the functional groups combine with calcium and magnesium ions, resulting in a decrease in the content of calcium and magnesium ions in the water and a decrease in its hardness. Hard water becomes soft water, which is the working process of water softening equipment.
When a large number of functional groups on the resin combine with calcium and magnesium ions, the softening ability of the resin decreases. A 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 groups will release calcium and magnesium ions to combine with the sodium ions, thus restoring the exchange ability of the resin. This process is called "regeneration".
Due to practical work requirements, the standard workflow of softened water equipment mainly includes five processes: work (sometimes called water production, the same below), backwashing, salt absorption (regeneration), forward washing, and salt tank water injection:
Backwashing has two main functions: first, to loosen the resin layer, allowing the salt solution to fully contact the resin layer, making the displacement reaction more thorough; second, to rinse off the suspended solids intercepted by the resin, which generally takes about 5-15 minutes.
Salt absorption (regeneration): The process of injecting salt water into a resin tank. Traditional equipment uses a salt pump to inject salt water, while fully automatic equipment uses a dedicated built-in sprayer to suck in salt water (as long as the inlet water has a certain pressure). In practical work, the regeneration effect of salt water flowing through the resin at a slower speed is better than simply soaking the resin in salt water. Therefore, softening water equipment adopts the method of slow flow of salt water through the resin for regeneration, which generally takes about 60 minutes. The actual time is affected by the amount of salt used.
Positive washing: In order to thoroughly rinse off residual salt, a flow rate similar to actual work should be used to rinse the resin with raw water. The final effluent of this process should be soft water that meets the standard. Generally, the fast flushing process takes 5-15 minutes.