A Gentle Method to Graft Thiol-Functional Groups onto Silica Gel for Adsorption of Silver Ions and Immobilization of Silver Nanoparticles
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Date
2012-10-22
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Abstract
Thiol-functionalized silica that has been used to remove heavymetal from an aqueous solution and supportmetallic
nanoparticles is usually synthesized by reflux in an organic solvent containing 3-mercaptopropyltrimethoxysilane
(MPTMS). In this paper, we report a gentle method for grafting thiol-functional groups onto silica gel by an aging
process that does not require mixing and refluxing in an organic solvent. Silica gel was synthesized by a sol–gel
method from H2SO4 (40%) and sodium silicate, which was crushed into beads with sizes ranging from 180 to
450 μm. Silica beads (50 g) were mixed with 75 mL of a functionalization solution consisting of MPTMS, H2O,
and C2H5OH and aged at 50 °C for 36 h in a box dryer. The success of the functionalization process was confirmed
by FT-IR, BET, SEM and elemental analyses. The functionalization solution was percolated into pores and thiolfunctional
groups were grafted onto the surface and pore walls of the silica beads. The ability of these functionalized
silica beads to adsorb silver ionswas determined by the Langmuir isotherm equationwith amaximumadsorption of
75.8 mg/g. Silver nanoparticles with sizes ranging from 2 to 6 nmformed by chemical reductionwere located inside
the pores and on the surfaces.
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