Hydrothermal Synthesis of Potassium Titanate Powders in Sub/Supercritical Water and Its Cobalt Ion Sorption Properties

Abstract

Hydrothermal synthesis of potassium titanate powders was carried out under various subcritical and supercritical water conditions (473-723 K) using titanium tetraisopropoxide and aqueous KOH solutions as starting materials. A single phase of K₂Ti₆O₁₃ was formed at 573 K or higher, whereas unidentified phase was obtained at 473K. In this paper, the hydrothermally synthesized potassium titanates powders were used for cobalt ion adsorbent under hydrothermal conditions. Co uptake on the hydrothermally synthesized K₂Ti₆O₁₃ was over 2x10^-3 molg^-1 at 473 K, whereas those at 373 K were lower in comparison with the solid state synthesized K₂Ti₆O₁₃. Cobalt ions can be adsorbed as Co₃O₄ accompanied by the structure transformation from K₂Ti₆O₁₃ to anatase under hydrothermal conditions.