Adsorption of lead (II) on SBA-15 mesoporous molecular sieve functionalized with -NH2 groups
Por:
Hernández-Morales V., Nava R., Acosta-Silva Y.J., MacÍas-Sánchez S.A., Pérez-Bueno J.J., Pawelec B.
Publicada:
1 ene 2012
Resumen:
SBA-15 substrate functionalized with -NH2 groups were tested in adsorptive elimination of lead (II) from aqueous solutions. The NH 2/SBA-15 adsorbents were prepared by grafting of synthesized SBA-15 substrate with different concentrations of 3-aminopropyltriethoxysilane (APTES) in order to determine the optimum amine group concentration. The largest adsorption capacity showed sorbent prepared using tetraethyl orthosilicate (TEOS)/APTES molar ratio of 3.3. All sorbents were characterized by N 2 adsorption-desorption isotherms, powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA-DTG) and X-ray photoelectron spectroscopy (XPS). Regardless of the concentration of amine groups, all synthesized NH2/SBA-15 samples showed higher adsorption capacity for Pb (II) ions than pure SBA-15 material. For the optimized sorbent formulation, experimental data showed that the maximum Pb (II) adsorption occurred in the range of pH 5-6 with adsorption maximum of 93%. The characterization of sorbents after Pb(II) adsorption by UV-vis and XPS spectroscopes point out to a mechanism of lead adsorption through van der Waals electrostatic interaction between Pb(II) ions and -NH2 groups located on the sorbent surface. The mechanism of lead adsorption through the ionic exchange of Pb(II) ions with surface Si-NH3+ groups, as determined by XPS, is precluded because they acts repulsively with approaching lead ions. © 2012 Elsevier Inc. All rights reserved.
Filiaciones:
Hernández-Morales V.:
División de Investigación y Posgrado, Facultad de Ingeniería, Universidad Autónoma de Querétaro (UAQ), 76000 Querétaro, Qro., México, Mexico
Nava R.:
División de Investigación y Posgrado, Facultad de Ingeniería, Universidad Autónoma de Querétaro (UAQ), 76000 Querétaro, Qro., México, Mexico
Acosta-Silva Y.J.:
División de Investigación y Posgrado, Facultad de Ingeniería, Universidad Autónoma de Querétaro (UAQ), 76000 Querétaro, Qro., México, Mexico
MacÍas-Sánchez S.A.:
División de Investigación y Posgrado, Facultad de Ingeniería, Universidad Autónoma de Querétaro (UAQ), 76000 Querétaro, Qro., México, Mexico
Pérez-Bueno J.J.:
CIDETEQ, S.C. Parque Tecnológico Querétaro - Sanfandila, Pedro Escobedo, Querétaro, México CP 76703, Mexico
Pawelec B.:
Instituto de Catálisis y Petroleoquímica, CSIC, Cantoblanco, 28049 Madrid, Spain
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