INVESTIGADORES
SAVIO marianela
congresos y reuniones científicas
Título:
Adsorption behavior of CNT and modified-CNT for their employment as a sorbent for solid phase extraction
Autor/es:
MARIANELA SAVIO; LUIS D. MARTINEZ; RAUL GIL; PATRICIA SMICHOWSKI; JONATHAN J TORREZ-HERRERA
Reunión:
Simposio; Eleventh Rio Symposium on Atomic Spectrometry (2010); 2010
Resumen:
A study was undertaken to asses the analytical capabilities of different types of nanotubes for their employment as a sorbent for solid phase extraction. The adsorption behaviors of different metals (Cd2+, Ni2+, and Pb2+) were evaluated on carbon nanotubes without modification (CNT) and carbon nanotubes functionalized with the L-alanine aminoacid (ala-CNT). The intermediate states that are part of the alanine immobilization process were also evaluated in order to establish the possible binding sites (edges). Thus, oxidized carbon nanotubes (o-CNT) and glutaraldehyde immobilized on oxidized carbon nanotubes (func-CTN) were studied. The overall methodology included an on-line coupling of the solid phase extraction system with flame atomization atomic absorption spectroscopy (FAAS). The analytes solutions at different pH values were loaded up to saturation. The retained metals were eluted with nitric acid. o-NTC were the CNTs configuration with the highest adsorption capability, following the next tendency o-NTC > ala-NTC > func-NTC > NTC. The maximum retention capacity was observed for Cd, corresponding to 123.22 µmol of Cd g-1 of CNTs at pH 9.0 on o-NTC. Comparing metals retention by the different CNTs configuration, the following tendency was acquired Cd > Ni > Pb. The data properly adjusted to a double exponential model when Cd and Ni were evaluated, in the case of Pb, only adjusted to a double exponential when the solution had low pH. Thus two kinetic constants were found for each element. (creo que habria que agregar algo sobre los modelos de ajuste, que permiten inferior la cinética, y el mecanismo de retencion para cada metal)