Adsorption of lead(II) ions from aqueous solutions onto Cr-pillared clays

The present paper presents the synthesis and characterization of porous nanomaterials, the Cr (III) being the metal oxide used as pillar intercalated between the layers of montmorillonite. The raw material used to obtain the pillared clays was a Romanian natural calcium bentonite, which was provided by S.C. Bentonita S.A. The main parameters were varied (metal ion for ion exchange process, aging temperature and duration for pillaring agent preparation, metal/clay ratio) in the aim of obtaining nanomaterials with high adsorption capacity of lead ions from waters. The modified clays were characterized by: nitrogen adsorption technique, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The determination of Pb(II) ions concentration was realized by atomic absorption spectrophotometry. The obtained results showed that the basal distance and specific surface area varied with the parameters of materials preparation. The nanomaterial with the best textural, structural and morphological properties was chosen in the aim of its using in Pb(II) adsorption from aqueous solution. The Langmuir and Freundlich models were used to fit the experimental data and these showed good correlations.