Soda ash has a tendency to absorb moisture from the atmosphere. The
moist soda ash then starts absorbing atmospheric carbon dioxide.
This phenomenon of absorption of moisture and carbon dioxide by soda
ash is known as weathering. After weathering, soda ash is likely to
contain appreciable moisture and sodium bicarbonate, but the total
alkali content of the bag does not change. Soda ash has a tendency
to cake when it comes in contact with moisture and, consequently,
becomes lumpy.
Chemical formula : Na2CO3
Characteristics |
IS 251 : 1998
specifications |
TCL-assured specifications |
Units |
Molecular weight |
|
106 |
|
Bulk density |
500 – 750 |
550 – 720 |
Kg/m3 |
Volatile matter content
(at the time of packing) |
2 |
0.80 |
%, max |
Total alkalinity (as Na2CO3) |
98.5 |
99.0 |
%, min |
Sulphates (as Na2SO4) |
0.08 |
0.03 |
%, max |
Chlorides (as NaCl) |
1.0 |
0.80 |
%, max |
Iron
(as Fe2O3) |
By colorimetric method |
|
0.0029 |
%, max |
By spectrophotometric method |
0.007 |
0.002 |
Matter insoluble in water |
0.15 |
0.03 |
%, max |
Light soda ash is one of the most important
basic industrial chemicals. Light soda ash is used to regulate
pH in many chemical process streams. The superior buffering
capacity of soda ash versus caustic soda offers advantages in
adjusting plant wastewater pH ranges.
Soda ash is used as the sodium source for
sodium sulfite/bi-sulfite pulping liquors used in the sulfite,
CMP, and CTMP processes, and in NSSC pulping.
It is also possible to replace a portion of
the caustic soda in many pulp bleaching applications such as
caustic extraction or hydrogen peroxide bleaching of mechanical
or chemical pulps. However, the higher pH requirements of these
applications may necessitate the continued use of some caustic
soda.
It is also possible to replace a portion of
the caustic soda in many pulp bleaching applications such as
caustic extraction or hydrogen peroxide bleaching of mechanical
or chemical pulps. However, the higher pH requirements of these
applications may necessitate the continued use of some caustic
soda.
In addition, it is the most widely used
fixed alkali for the manufacture of other alkali products,
sodium salts, glass, soap, sodium silicates, detergent,
bicarbonates, bichromates, cellulose and rayon, iron and steel,
aluminum, cleaning compounds, textiles and dyestuffs, drugs and
many other materials. It is also used as an alkali for household
purposes and as washing powder by laundries.