Detergents, soaps and purification

Sodium bentonite is the
constituent of many detergents used in UK, USA and Germany for scouring textiles. The role
of bentonite is to adsorb the dirt particles through exchange of cations. Besides the type of
bentonite, swelling capacity, fineness of size, pH and content of grit particles are important
criteria. The industries specify 10 ml swelling capacity, (-) 240 mesh size, neutral to slightly
alkaline solution (pH 8-9) and freedom from grit. The sodium type of bentonite and the
swelling capacity ensure good cation-exchanging and adsorptive capacities. Fine size means
longer duration of suspension and larger availability of surface area for adsorption. Acidic or
strongly alkaline solution may corrode the textile and grit will tend to damage the threads
while scouring.
Bentonite is used in certain soaps to the extent of 25 percent.
Bentonite is effective in purification of sewage and turbid water. Here again, the criteria
are its base-exchanging capacity, fine particle size with large available surface area and
ability to remain in suspension for a long time.