Nanoscale zero-valent iron supported on mesoporous silica: Characterization and reactivity for Cr(VI) removal from aqueous solution

• Published in: Journal of hazardous materials Vol. 261; pp. 295 - 306
• Main Authors: Petala, Eleni, Dimos, Konstantinos, Douvalis, Alexios, Bakas, Thomas, Tucek, Jiri, Zbořil, Radek, Karakassides, Michael A.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15-10-2013; Elsevier
• Subjects: Adsorption; Applied sciences; Atmospheric pollution; Characterization; Chemical engineering; Chromium - chemistry; Cr(VI) remediation; Exact sciences and technology; Iron - chemistry; Kinetics; Mesoporous silica; Nanoscale zero-valent iron; Pollution; Porosity; Reactors; Silicon Dioxide - chemistry; Solutions; Water Pollutants, Chemical - chemistry; Water Purification - methods; Characterization; Nanoscale zero-valent iron; Kinetics; Cr(VI) remediation; Mesoporous silica; Nanoparticle; Zerovalent metal; Iron III Chlorides; Ultrafine particle; Modeling; Powder; Chemical reduction; Decontamination; pH; Chemical reactivity; X ray diffraction; Kinetic model; Transmission electron microscopy; Analysis method; Adsorption; Morphology; First order; Aerosols; Air pollution; Thermal analysis; Aqueous solution; Surface area
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2013.07.046

•New nanohybrid exhibits magnetic and molecular sieves properties.•Material shows well dispersed and stabilized ZVI nanoparticles on inorganic support.•Material demonstrates high Cr(VI) chemical reduction efficiency.
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 ∼80nm, 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 (609m2/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.