Preparation and characterization of amorphous silica nanowires from natural chrysotile

By chemical dispersing and acid leaching, silica nanowires have been prepared from the natural mineral, chrysotile. X-ray fluorescence analysis (XRF), thermogravimetric analysis and differential thermogravimetric analysis (TGA-DTA), powder X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterize the silica nanowires. The results indicate that the chemical composition of the silica nanowires is SiO(1.8) center dot 0.6H(2)O, and although the silica is amorphous, its structure is regular to some extent. The structural unit of the silica nanowires is the [SiO(4]) tetrahedron and six-member silicon-oxygen ring with the tetrahedral positioned alternately up and down in the six-member ring. The silica nanowires are well-dispersed and have cylindrical morphology and smooth surface, with lengths over 10 Pill and diameters of 30-60 nm. (C) 2007 Elsevier B.V. All rights reserved.