Abstract

This study seeks to devise a method that allows us to reduce the pollution parameters of the waste waters produced during the transformation of hides into leather. Tanning with vegetable extracts contributes to the COD values of the resulting waste waters and thus we have investigated the possibility of eliminating vegetable extracts by means of adsorption with bentonite. The influence of the acid activation level of the bentonite on its adsorption capacity has also been studied.

Natural bentonite activated with sulphuric acid 0.5 N is the most suitable adsorbent for removing mimosa extract. The isotherm of adsorption of mimosa extract with bentonite seems to be of the L type in accordance with the classification given by Giles. This mechanism implies that as more sites in the substrate are filled, it becomes increasingly difficult for a new solute molecule to find a vacant site. The adsorption process gives rise to a diminution of the COD values as expected.