BENTONITE AND ITS MODIFIED DERIVATES AS ADSORBENTS OF LEAD

11th International Multidisciplinary Scientific GeoConference SGEM2011, www.sgem.org, SGEM2011 Conference Proceedings/ ISSN 1314-2704, June 20-25, 2011, Vol. 3, 199-206 pp

ABSTRACT

The main objective was to study the removal of lead cations from aqueous solutions by
sorption onto bentonite and its modifications. Modification included natrification by
NaCl and intercalation by octadecylamine (ODA) in two different weight ratios. The
sorption isotherms were described using the Langmuir and Freundlich models. The
adsorptive capacities of the original bentonite increased after the intercalation of ODA.
Adsorption of Pb ions, calculated by the Langmuir model, yielded 97.15mg of Pb ions
on 1g of bentonite (a sample intercalated by ODA in the weight ratio bentonite:ODA of
1:0.75). This sample was the most suitable for lead adsorption. The natrified sample
also achieved better values of uptake capacity than the untreated bentonite, however, the
contrast was not so obvious. The mechanisms of lead uptake are ion-exchange
adsorption onto untreated bentonite and ion exchange plus Pb2+ octadecylamine
complexation on the modified bentonite.

Keywords: adsorption, bentonite, modification, sorption isotherm, lead.