title: Nanoscale zero-valent iron supported on mesoporous silica: characterization and reactivity for Cr(VI) removal from aqueous solution.
abstract: MCM-41-supported nanoscale zero-valent iron (nZVI) was sytnhesized by impregnating the mesoporous silica martix with ferric chloride, followed by chemical reduction with NaHB4. The samples were studied with a combination of characterization techniques such as powder X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) and Mössbauer spectroscopy, N2 adsorption measurements, transmission electron microscopy (TEM), magnetization measurements, and thermal analysis methods. The experimental data revealed development of nanoscale zero-valent iron particles with an elliptical shape and a maximum size of ∼80 nm, which were randomly distributed and immobilized on the mesoporous silica surface. Surface area measurements showed that the porous MCM-41 host matrix maintains its hexagonal mesoporous order structure and exhibits a considerable high surface area (609 m(2)/g). Mössbauer and magnetization measurements confirmed the presence of core-shell iron nanoparticles composed of a ferromagnetic metallic core and an oxide/hydroxide shell. The kinetic studies demonstrated a rapid removal of Cr(VI) ions from the aqueous solutions in the presence of these stabilized nZVI particles on MCM-41, and a considerably increased reduction capacity per unit mass of material in comparison to that of unsupported nZVI. The results also indicate a highly pH-dependent reduction efficiency of the material, whereas their kinetics was described by a pseudo-first order kinetic model.
authors: Department of Materials Science and Engineering, University of Ioannina, GR-45110 Ioannina, Greece; Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University, 17.listopadu 1192/12, 771 46 Olomouc, Czech Republic.
authors: Eleni
authors: E
authors: Petala
authors: Konstantinos
authors: K
authors: Dimos
authors: Alexios
authors: A
authors: Douvalis
authors: Thomas
authors: T
authors: Bakas
authors: Jiri
authors: J
authors: Tucek
authors: Radek
authors: R
authors: Zbořil
authors: Michael A
authors: MA
authors: Karakassides
mesh_terms: D002857:Chromium / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D012996:Solutions; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: C509968:MCM-41; D012996:Solutions; D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion; D012822:Silicon Dioxide; D007501:Iron
keywords: Characterization; Cr(VI) remediation; Kinetics; Mesoporous silica; Nanoscale zero-valent iron