Water:
Water is a complex compound. It
is very important compound in textile wet processing. The total amount of water
in the world is about 75%. Natural water is obtained in 3 steps. They are
solid, liquid & vapor. Water has a un-comparable power to dissolve other
compound. It is very difficult to obtain pure water in nature. Water is
consists of two part Hydrogen & one part Oxygen. Its chemical formula is
H2O. Water is converted to ice at 0°C & converted to vapor at 100°C the
concentration of water is highest at 4°C.
Classification of water:
Classify
water on the basis of hardness:
DESCRIPTION
|
TOTAL HARDNESS
(degree)
|
Very soft
|
0 - 4°
|
Soft
|
5 - 8°
|
Mild
|
9 - 14°
|
Fairly mild
|
15 - 18°
|
Hard
|
19 - 30°
|
Very hard
|
>30°
|
Classify water on the basis of
source:
On the basis of source water
may be classified into followings-
1) RAIN WATER:
- Rain, collected immediately after recitation, is the purest of all natural water.
- It may contain traces of gases dissolved out of the atmosphere & possibly an almost infinitely small amount of finely divided solid matter derived from the air.
- It also contain dissolved or Sulfur DI-oxide or Sulfuric acid, CO2, NH3, NO2 & other by products of industrialization.
- Suspended impurities present in it, can be filtered by using sand bed.
- Suitable for boiling, washing & dyeing process.
2) SURFACE WATER:
- Surface water may consists of rain water which has collected from streams, rivers or lakes.
- This type of water contains organic & inorganic matters which are dissolved in it
- & also contain suspended impurities.
- Then the nutrifying bacteria will in time convert the organic substances into nitrates which are not objectionable in dyeing & printing.
- Surface waters may receive considerable additions of dissolved mineral salts from shallow springs which feed the streams.
- It contains Chloride, Sulfate, Carbonate, Bicarbonate of Na, P, Ca & Fe.
- Not suitable for dyeing & finishing.
3) SUBSOIL WATER:
- This type of water is collected from shallow springs & wells which are about 50 ft (15 m) or so deep.
- It is usually free from suspended impurities because it has been filtered by its passage through the soil. It'll however contain dissolve organic water.
- Subsoil water is often rich in dissolved Carbon di oxide, a gas abundantly present in the skin of the soil.
- Subsoil waters are very variable with regard to the impurities which they contain.
- Not suitable for dyeing & finishing.
4) DEEP WELL WATER:
- This type of water is obtained from 500 m below the surface. It is free from organic matters.
- The soluble impurities in water may be composed of a variety of substances. Soluble organic compounds, ammonium salts, Nitrates & Nitrites of animal; or vegetable origin may be found. If they are present in considerable quantities, the sewage contamination is undesirable for many textile purposes.
- The presence of salts of Ca or Mg in solution can be most undesirable in many finishing process.