What chemical is used to regenerate exhausted natural zeolite for softening?

The regeneration of exhausted natural zeolite for softening is achieved using sodium chloride, commonly known as table salt. Zeolite works by exchanging sodium ions for hardness ions like calcium and magnesium present in water. Over time, the zeolite becomes saturated with these hardness ions and loses its effectiveness in softening water.

To restore the zeolite’s ability to soften water, sodium chloride is introduced, which helps to displace the hardness ions attached to the zeolite. When sodium chloride is dissolved in water, it dissociates into sodium ions and chloride ions. The sodium ions then replace the calcium and magnesium ions on the zeolite, effectively regenerating its softening capacity. This process is crucial in water treatment systems that utilize natural zeolite for softening purposes, ensuring the continuous removal of hardness from the water supply.

The other options, while they may have some relationship with water chemistry, do not function in the same way for the regeneration of zeolite. Calcium chloride and magnesium chloride would not effectively regenerate zeolite because they would introduce additional hardness ions rather than replace them. Potassium chloride can be used in some specific applications, but sodium chloride is the standard option for regenerating zeolite in softening processes.