Synthesis and characterization of organo-montmorillonite supported iron nanoparticles

Iron nanoparticles show great reactivity in the remediation of groundwater and soil or other environmental applications, however, the persistence and dispersion of iron nanoparticles need to be improved. In this study, environment-friendly montmorillonite (Mont) and hexadecyl trimethylammonium modified montmorillonite (HDTMA-Mont) were used to support iron nanoparticles (denoted as Mont/iron and HDTMA-Mont/iron particles). The specific surface areas of the supported iron nanoparticles were 28.7 m2/g and 38.1 m2/g, while for unsupported nanoparticles 24.3 m2/g. The presence of organo-montmorillonite apparently decreased the extent of aggregation and the size of the iron particles. Iron and crystalline iron oxide were detected by X-ray diffraction (XRD) patterns. In the Fourier Transform Infrared spectrum, CH2 groups were present in HDTMA-Mont but not found in HDTMA-Mont/iron particles. From the results of X-ray photoelectron spectroscopy (XPS), iron nanoparticles had a core–shell structure with the core being iron, and the shell consisting of iron (hydr)oxides. In contact with Cr(VI), the reduction of Cr(VI) was highest with HDTMA-Mont/iron particles, followed by Mont/iron particles and free iron nanoparticles.

Research Highlights
► Organo-montmorillonite decreases the extent of aggregation and the size of the iron particles.
► Supported iron nanoparticles have a core–shell structure.
► Supported iron nanoparticles have better performance in the removal of Cr(VI) than unsupported iron nanoparticles.