(i) Gas masks are devices containing suitable adsorbents so that poisonous gases present in the atmosphere are preferentially adsorbed and the air for breathing is purified.
Activated charcoal is one of the best adsorbents.
(ii) Permutit is employed for this process which adsorbs Ca2+ and Mg2+ ions in its surface, there is an ion exchange as shown below it occurs on the surface.
Exhausted permutit is regenerated by adding a solution of common salt.
(iii) Sugar prepared from molasses is decolourised to remove coloured impurities by adding animal charcoal which acts as decolourising material.
