Study of titanium(IV) speciation in sulphuric acid solutions by FT-Raman spectrometry

The effects of the addition of titanium(IV) to aqueous solutions of sulphuric acid were studied by FT-Raman spectroscopy. Solutions containing 0 M to 4.01 M of titanium(IV) and 1.98 M to 6.17 M of sulphuric acid were analysed. A new peak, characteristic of titano-sulphate complexes, has been observed, in addition to the peaks characterising ions SO42− and HSO4−. Free HSO4− and SO42− concentrations have been determined from the Raman peak areas. From mass balance it was deduced that two complexes are present in the solution: [Ti(OH)2SO4] (aq) and [Ti(OH)2(SO4)2]2− (aq). Their apparent constants of formation have been estimated.