Removal of zirconium from hydrous titanium dioxide

Abstract

A method was proposed for removing zirconium (Zr) from hydrous titanium dioxide (HTD) by the NaF solution. The effects of main parameters, i.e. pH values, NaF dosage, temperature and retention time, on the removal of zirconium were studied. The optimal conditions were found as the following: pH value, <5.5; molar ratio of NaF to TiO₂, 0.6; retention time, 80 min; and temperature, 80°C. The removal rate of Zr under the optimized conditions was above 87.7%. The adsorption energy of the preferential absorption of hydrofluoric acid for Zr(OH)₂SO₄(OH₂) on the (001) crystal surface of HTD was determined by theoretical calculation. The possible mechanism of the removal process was also discussed.

Keywords

zirconium / titanium dioxide / removal / density functional theory / microstructure / adsorption

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