Complex equilibria in aqueous solutions of Ti3+–glycine and –malonic acid

Abstract

The hydrolytic processes of Ti³⁺ and the equilibria of the Ti³⁺–glycine (HL) and –malonic acid (H₂L′) systems were studied by pH-metry in aqueous solution (25 °C, I= 1.0 mol dm^–3 KCl). It was demonstrated that more than one equilibrium model are suitable to interpret the hydrolytic reactions. In the Ti³⁺–glycine system the formation of complexes [TiHL]³⁺ and [TiL]²⁺ were identified; their stability constants are logβ_TiHL= 11.44 and logβ_TiL= 9.30. For the malonato complexes the following stepwise stability constants were determined: logK₁= 6.83, logK₂= 4.99, and logK₃= 2.84. Some aspects of the equilibrium of Ti³⁺ are discussed.