Synthesis and characterization of Fe(III)-silicate precipitation tubes

Fe(III)-silicate precipitation tubes synthesized through “silica garden” route have been characterized using a number of analytical techniques including X-ray diffraction, infrared spectroscopy, atomic force microscopy, scanning and transmission electron microscopy. These tubes are brittle and amorphous and are hierarchically built from smaller tubes of 5-10 nm diameters. They remain amorphous at least up to 650 °C. Crystobalite and hematite are the major phases present in Fe(III)-silicate tubes heated at 850 °C. Morphology and Chemical compositions at the external and internal walls of these tubes are remarkably different. These tubes are porous with high BET surface area of 291.2 m2/g. Fe(III)-silicate tubes contain significant amount of physically and chemically bound moisture. They show promise as an adsorbent for Pb(II), Zn(II), and Cr(III) in aqueous medium.