Which process is primarily responsible for removing hardness from water in ion exchange softeners?

The process responsible for removing hardness from water in ion exchange softeners is exchanging salts. This process involves the exchange of calcium and magnesium ions, which contribute to water hardness, for sodium ions. In an ion exchange system, water passes through a resin bed containing sodium ions. As the hard water flows through, the calcium and magnesium ions are attracted to the resin and displace the sodium ions. This exchange effectively reduces the hardness of the water, making it softer and more suitable for various applications, such as household uses or industrial processes. The ability of the resin to selectively attract and hold onto these hardness ions while releasing sodium ions is what makes this process effective for softening water.