Estudios de Adsorción de Pb en una montmorillonita pilareada con SiO2-Cr2O3

A. MERCADO; EDGARDO SHAM; ELSA MÓNICA FARFÁN TORRES

Las Fronteras de la Física y Química Ambiental en IberoAmerica

Universidad Nacional de San Martin

Lugar: Buenos Aires; Año: 2008; p. 320 - 326

In the present work the use of an Argentine montmorillonite pillared with SiO2-Cr203 nanoparticles as a sorbent for the removal of Pb (II)was evaluated. In the pillaring process 3-amine-propyl-triethoxysilan (APTEOSi), sílicon tetraethoxide (TEOS), and chromium (III) nitrate , were used as precursors of the mixed pillars. The clays calcíned at 500°C were named PESPSiCr-01 and PESPSiCr-03 respectively. The basal spacíngs for the calcined clays were 9,56 Å (PESP-Na), 32 Å (PESPSiCr-01) and 15,38 Å ( PESPSiCr-03). The FTIR demonstrate the presence of bands attributed to stretching modes typical of this type of materials. The obtained results show that the clay PESPSiCr-01 calcined at 500 ºC is completely deshydroxylated, whereas in the PESPSiCr-03 this process still does not take place. The batch adsorption process for Pb2+ and Pb2+ in the presence of Ca 2+ was studied, in aqueous media and room temperature. The results show that the adsorption behavior can be described by the Langmuir model. The qmax for Pb2+ reaches values of up to 139,1 mg Pb2+/g clay. The FTIR studies indicate that the clay sheet structure was not altered during the Pb 2+ adsorption. The Eads determined from the model of Dubinin-Raduskevich corresponds to 33,3 kJ/mol, which would indicate that the process of retention takes place basically by means of ionic exchange reactions at the surface sites located at the clay layered surface, the nanoparticles and the clay borders. The pillared clay presents pronounced affinity towards the Pb(lI) adsorption still in the presence of Ca2+, with a factor of separation, α2, of 2,58.