en |
Algerian natural montmorillonites for arsenic(III) removal in aqueous solution
Zahhaf, A.; Benyoucef, A.; Quijada, C.; Taleb, S. & Morallón, E.
Abstract
The adsorption of As(III) from aqueous
solutions using naturally occurring and modified Algerian
montmorillonites has been investigated as a function of
contact time, pH, and temperature. Kinetic studies reveal
that uptake of As(III) ions is rapid within the first 3 h,
and it slows down thereafter. Equilibrium studies show
that As(III) shows the highest affinity toward acidic
montmorillonite even at very low concentration of
arsenic. The kinetics of As(III) adsorption on all montmorillonites
used is well described by a pseudo-secondorder
chemical reaction model, which indicates that the
adsorption process of these species is likely to be
chemisorption. Adsorption isotherms of As(III) fitted the
Langmuir and Freundlich isotherm models well. The
adsorption of As(III) is pH-dependent obtaining an
optimal adsorption at pH 5. From the thermodynamic
parameters, it is concluded that the process is
exothermic, spontaneous, and favorable. The results
suggest that M1, M2, and acidic-M2 could be used as
low-cost and effective filtering materials for removal of
arsenic from water.
Keywords
Adsorption; Clay; Ion exchange; Arsenic; Montmorillonite
|