AMINOPROPYL-MODIFIED MESOPOROUS SILICA NANOSPHERES FOR THE ADSORPTION OF Cr(VI) FROM WATER

N. A . FELLENZ; P. MARTIN; S. G. MARCHETTI; J,F. BENGOA

JOURNAL OF POROUS MATERIALS

SPRINGER

Lugar: Berlin; Año: 2015 vol. 22 p. 729 - 738

1380-2224

Aminopropyl-functionalized mesoporous silicaspherical particles were obtained through post-syntheticroute. The suitability of this material as an adsorbent forheavy metals from aqueous media was tested by Cr(VI)adsorption experiments performed at various pH conditions,chromium concentrations and time. The synthesized particleswere characterized before and after functionalizationby X-ray diffraction at low angles, nitrogen adsorption?desorption isotherms, infrared Fourier transform spectroscopy,scanning electron microscopy and thermogravimetricanalysis. It was found that Cr(VI) adsorption occursmore efficiently in the pH range between 2 and 3. As aconsequence of the nanometer scale of the particles, concentrationprofiles do not develop inside of them and thusthere are no diffusional restrictions within the pores, leadingto a higher Cr(VI) adsorption than that previously reportedfor similar systems. Chromium desorption for material reutilizationwas carried out in basic media. Results showedthat the amino groups were grafted successfully withoutmesostructure damage. These groups are essential for themetal ion removal and no significant leaching was observedafter four use/regeneration/use cycles. The batch equilibriumdata fitted well the Langmuir isotherm with a maximum adsorption capacity of 87.1 mg g-1 at 25 C. A discussionabout the relationship between structure and its behavior asadsorbent, including regeneration and reusability, is given.