Water Softening

The process of reducing the concentration of ions like calcium, magnesium and related from water is referred as water softening. These ions are called as hardness inducing ions. It may cause deterioration effect when it interacts with soap. It induces foul plumbing and galvanic corrosion of materials. If the water is hard, then water softening is must. However hard ions prove benefit to human beings by providing calcium, magnesium and metals like copper and lead never dissolves in hard water. Water softening device for domestic applications shall utilize ion exchange resins such as sodium ions.

Water softening methods

The main aim of water softening is to remove the calcium ion and magnesium ions from the solution that are bound together or obstruct detergent activity. Ions can be removed either by precipitation method or by ion exchange method. Sequestration allows addition of new chemical compounds and is referred as chelating agents or sequestration agents.  The salts such as calcium and magnesium cannot be volatilized and hence it can be removed by proper distillation of water. However distillation is a cost effective process. An ion exchange resin has sodium ions which are bound together electro statically and can be easily replaced by calcium ions and magnesium ions.  Resins are usually univalent ions like sodium, at times hydrogen and potassium can be used in place of sodium. Sodium bound to anionic functional group of organic polymers that are present in ion exchange resins. Zeolite also exhibit same characteristics as sodium, hence it is used in laundry detergents. Water passes through the resin bed. Positively charged ions couple with negatively charged resins.  Calcium and magnesium ions will replace the sodium that is present in water. Increased release of sodium ions, hydrogen and potassium ions indicate that the water is too hard. Water softening is essential in industrial plants where the effluent flows out from regenerating process.

Questions:

• What are health effects of sodium?
• What are chelating agents?
• What is the need for water softening?