Bentonite is a kind of absorbent clay.s high absorbency makes it a useful substance in industrial applications, in products like kitty litter and even in natural medicine.
There are different types of bentonite which are named after their dominent element like potassium, sodium, calcium, and aluminium.
Sodium bentonite has property which expands when wet, absorbing as much as several times its dry mass in water. It is commonly used in drilling mud for oil and gas wells and boreholes for geotechnical and environmental investigations. Its property to swell makes it usable to seal, as it provides self-sealing, low permeability barrier.
Calcium bentonite is a useful absorbent of ions in solution, as well as fats and oils. It is the main active ingredient of fuller’s earth, probably one of the earliest industrial cleaning agents.
Calcium bentonite may be converted to sodium bentonite to exhibit many of sodium bentonite’s properties by an ion exchange process. In common usage, this means adding 5–10% of a soluble sodium salt such as sodium carbonate to wet bentonite, mixing well, and allowing time for the ion exchange to take place and water to remove the exchanged calcium. Some properties, such as viscosity and fluid loss of suspensions, of sodium-beneficiated calcium bentonite may not be fully equivalent to those of natural sodium bentonite.For example, residual calcium carbonates may result in inferior performance of the bentonite in geosynthetic liners.