removal of permanent hardness of water

7/22/2019 Removal of Permanent Hardness of Water

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1) By the use of soda

2) Other softening agents in the home

They are:a) Soap

b) Caustic soda

c) Solution of Ammonia

d) Borax

3) By the Base-Exchange Process

Permanent hardness of water can be a

removed by the following ways:



By the use of soda:

Soda removes both temporary and permanent

hardness. It is also inexpensive and easy to use. Thismakes it the ideal substance for softening water in thehome.

Other softening agents in the home:

It is difficult for the housewife to be very precise in theuse of soda and the water softened by soda may oftencontain an excess of it, which even if it is slight, maydamage certain fabrics. Hence, other softening agents

could be used. They are:



Soap:

Soap is used as a softening agent. However, the use of

soap as a softening agent is extravagant on account ofits high cost compared with soda.

Caustic soda:

It removes temporary hardness but reduces permanenthardness only when the lather is very slight



Solution of Ammonia:

It may be used for softening water, when the fabrics to

be treated would be harmed by soda. If used in excess,ammonia may destroy the Iustre of rayon's, discolourand injure animal fabrics and loosen the dyes ofcoloured articles. Since, it is not possible to be very

certain of the quantity to be used; this is notpracticable for softening water.



Borax:

It is useful for softening water containing over 20% of

hardness. Borax is usually used to reduce the alkalinityof soap solution rather than to soften water.

(3) Removal of Permanent Hardness by the Base-Exchange Process:

Base exchange process' is a chemical method by which,softening of permanent hardness in water can be doneon a large scale or for household purposes. It is the

most popular and effective means of softening hard water. It was discovered by Dr. Robert Gans, whofound out the natural minerals called 'Zeolites', whichis very effective in softening water,



The Base-Exchange Process includes the followingprocedures:

The water passes through specially prepared zeolite- a sodium

compound, called base-exchange compound. it is has theproperty of being able to exchange its sodium base for another. When hard water passes through the zeolite, the hardeningcompounds of calcium and magnesium are caught up by thezeolite and become compounds of sodium. Since sodium salts in

water do not precipitate out on heating or form soap curds the

water is called 'soft'. When a given quantity of water, determined by the size of the

appliance, has been softened, the zeolite becomes depleted;having parted with all its sodium, but this can be remedied, asthe substance has the property of being able to exchange its baseagain and to take back sodium in place of calcium and

magnesium. This process is called 'regeneration'.Zeolite watersofteners made for domestic use are either connected with themen water-supply or fixed on to a water tap

removal of permanent hardness of water

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