Analysis of basic chemicals used in textile processing

 

In textile processing a lot of basic chemicals or bulk chemicals such as common salt, soda ash.sodium bicarbonate, sodium silicate and organic and inorganic acids such as Hydrochloric acid, sulphuric acid, acetic acid etc are being used. The quality of each product will definitely play an important role in the cost and final quality of the finished fabric. so basic knowledge of these chemicals and their testing methods in a small lab with some common analytical instruments like burettes, pippettes etc is very much essential for a processing personal.

Bulk chemicals can be widely divided in to acids, alkalies and salts.

In this section we can see the basic characters of acids, alkalies and salts.

Most inorganic acids used in textile processing are liquid in nature and they are highly corrosive. It will burn out the skin and other organs if we directly come in to contact with acids. Acids have a pH value less than 7 at all its concnetrations. If at all you happen to come in to contact with acids, wash immediately with lot of water in a running tap. If injured, get the assistance of a qualified doctor.

Most inorganic alkalies or bases are solids and they are also corrosive in nature. Alkalies have a pH value of above 7 at all its concentrations. Since alkalies also affect the skin badly, one should wash off with as luch water as possible to remove all the traces of alkali.

Salts are generally reaction products of an acid and an alkali. eg., Hydrochloric acid and Sadium hydroxide on reaction yields Sodium Chloride and water, where sodium chloride is our common salt.

Since acids, alkalies and salts can be easily adulterated naturally and otherwise, its always necessary to test the purity of the ingredients before making use in textile processing.

TABLE OF APPROXIMATE pH OF SOME COMMON ACIDS AND BASES
AT VARIOUS CONCENTRATIONS.
NORMALITY/ 2N 1N 0.1N 0.01N 0.001N
MATERIAL
Hydrochloric acid g/l --- 36.5 3.65 0.37 0.037
HCl pH 0.11 1.08 2 3
Sulphuric acid g/l 49 4.9 0.49 0.049
H2SO4 pH 0.24 1.17 2.05 3
Formic acid g/l 92 46 4.6 0.46 0.046
HCOOH pH 1.61 1.79 2.32 2.85 3.42
Lactic acid g/l 180 90 9 0.9 0.09
C3H6O3 pH 1.78 1.97 2.43 2.95 3.5
Acetic acid g/l 120 60 6 0.6 0.06
CH3COOH pH 2.18 2.4 2.87 3.37 3.89
T.S.P.P. g/l --- 83 8.3 0.83 0.083
Na4P4O7 pH 10.5 10.15 9.25 9.01
Soda Ash g/l 106 53 5.3 0.53 0.053
Na2CO3 pH 11.6 11.5 11 10 9.8
Ammonia (Hydroxide) NH4OH g/l 34 17 1.7 0.17 0.017
pH 11.72 11.59 11.16 10.64 10.15
Trisodium phosphate g/l 98.6 49.3 4.93 0.493 0.049
Na3PO4 pH 12.8
12.3
11.4
11.1
10.95
Caustic soda g/l  
40
4
0.4
0.04
NaOH pH
13.93
12.98
12
11