Abstract

A novel route of extracting titanium using tannic acid from ilmenite was investigated. The strong affinity of tannic acid towards metal ions having high oxidation states was explored to extract titanium selectively from a multi-element solution prepared by dissolving ilmenite in sulphuric acid and ammonium sulphate. Titanium-tannic acid complex was selectively precipitated from the multi-element solution at pH 4.5. The precipitate was separated by vacuum filtration and the filter cake was washed with 2% hydrochloric acid solution, deionized water and isopropyl alcohol after filtration. The washed filter cake was dried at room temperature and ground into powder on drying. The titaniumtannic acid complex so obtained was composed of 98.6% of titanium, 0.2% of iron and 1.2% of other impurities. The density functional theory simulation at B3LYP method with a basis of 6-31G was also conducted to verify optimized structure and its stability. The result showed energy gap of 2.43 eV between two frontier orbitals (highest occupied molecular orbitals and lowest unoccupied molecular orbitals), which is large enough to indicate energetic feasibility of the complex formation.

Keywords: Tannic acid; Titanium; Ilmenite; Digallic acid; Density functional theory simulation