Removal of Hardness of Water

Removal of Hardness of Water

Methods for removing temporary hardness of water

This hardness of water can be removed by two methods. That is by boiling or heating and By Clark’s method.

By boiling or heating

 Temporary hardness of water can be removed easily by just boiling or

Heating it because boiling or heating can change the soluble bicarbonates of Ca and Mg into the insoluble carbonates which can be easily removed by decantation or filtration. Such as

                          

By Clark’s method

 In this method temporary hard water containing hydrogen carbonates or bicarbonates of Ca an Mg are treated with slaked lime Ca(OH)₂ in carbonates which settle down at the bottom of tanks while soft water is decanted off or filtrated. Such as

          

Methods for removing permanent hardness of water

 permanent hardness of water is very difficult to remove by using special type of methods. There are two methods as follow of removing permanent hardness of water.

By reaction with washing soda (Na₂CO₃)

 As hard water contains the Mg and Ca Chloride and Sulfate so, When washing soda is added to the permanent hard water then the insoluble calcium carbonate and magnesium carbonate precipitate are formed from

The soluble salt of Ca and Mg. such as

                           Na₂CO_{3 (aq)}     +     CaSO_{4 (aq)}    •••►      CaCO_3(s)      +       Na₂SO_{4 (aq)}

By Ion exchange method

 This method is used for the removal of both temporary and permanent hardness of water. In this method permanent hard water is reacted with sodium zeolite (sodium

Aluminum silicate (Na Al SiO₃) which is a salt. As jard water contains the Sulphate and Chloride of Ca and Mg then they react with the Zeolite (AlSi) and the insoulne substance is formed belwo and can br removed by decantaion. Such reactions are as follow          

                         Na₂ – Zeolite     +    CaSO_{4 (aq)}      •••►    Ca - Zeolite    +    Na₂SO_{4 (aq)}

Disadvantage of using hard water or effects of hard water

The following disadvantages are as follow

• Hard water cannot produce good lather with soap and other shampoos etc. therefore skin, scalp (such part below our hair) or cloths do not clean easily.
• Hair washed with hard water become rough and harder to detangle.
• Insoluble salts in hard water not only blocks the boilers and pipes but can cause blasts. Such as accidents have causes loss of lives many times.

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