Synthesis and physicochemical properties of biomorphic zirconia fibers

Biomorphic zirconia fibers were prepared by successive carbonization and/or calcining of sawdust impregnated by a solution of zirconium oxynitrate. Pyrolysis was performed in nitrogen (500°C), and calcining, in air (600°C). The physicochemical characteristics of samples were studied by adsorption measurements, electron microscopy, and X-ray diffraction. The biomorphic fibers were composed of zirconia nanoparticles not larger than 12 nm. The samples had a uniform phase composition dominated by the tetragonal ZrO₂ phase; their specific surface area was 13–38 m²/g depending on the salt content in sawdust. It was assumed that the stabilization of the tetragonal phase could be related to the incorporation of mineral components (calcium, magnesium, and potassium compounds) of sawdust into zirconia; carbonization had no substantial effect on the properties of the resulting oxide. The method developed could be used to obtain tetragonal zirconia (without expensive reagents and water consumption) and utilize wood industry wastes.