Abstract: Various of nanometer-size TiO₂ samples are prepared from TiCl₄ under different hydrolysis and calcining treatment conditions, such as pH, surfactants, stabilizers and temperature. It has been found that powders heat-treated at the temperature below 450 ℃ are of anatase crystal structure with average grain size of less than 20 nm. Adsorption behavior of Cr(Ⅵ) ion on as-prepared powders, adsorption kinetics, pHcurves, adsorption isotherms and adsorption capacity are studied by flow-injection micro column system for preconcentration using spectrophotometric detection method. The results demonstrated that nanometer-size TiO₂ possesses a significant capacity and exchange rate for adsorption of Cr(Ⅵ) ion(approximately 3080 μg/g and 8.6×10³ s^-1).

Key words: Nanometer-size TiO₂, Adsorption kinetics properties, Chromium(Ⅵ), On-line flow injection analysis