TITLE:
Characterization and Modification of a Clay Mineral Used in Adsorption Tests
AUTHORS:
Natália Costa Dias, Patrícia Arns Steiner, Maria Cristina Borba Braga
KEYWORDS:
Adsorption Isotherms, Adsorption Thermodynamics, Clay Minerals, Expanded Vermiculite, Landfill Leachate, Vermiculite
JOURNAL NAME:
Journal of Minerals and Materials Characterization and Engineering,
Vol.3 No.4,
June
12,
2015
ABSTRACT: Clay minerals are widespread in natural systems and have been widely used for the removal of
pollutants. In this study, natural expanded vermiculite was used in adsorption tests to remove
ammonium nitrogen from landfill leachate. The modification of vermiculite was carried out using
NaOH and HCl, and for both modifications the best concentration was 0.1 mol/L. The results produced
by XRD (X-ray diffraction) showed that Al replaced K after modification of the vermiculite
using HCl and that Mg and Na replaced K after modification using NaOH. It was observed that the
adsorption capacity increased as the percentage in mass of K diminished. The Langmuir is the isotherm
that presents the best fit of the data, and the values of RL (the Langmuir coefficient) suggest
that the adsorption is linear. The thermodynamic parameters indicate that the process is spontaneous
and endothermic, that there is a high affinity between the adsorbate and the adsorbent, and
that physical adsorption is prevalent.