Studies on kinetics, thermodynamics and sorption characteristics of an inorganic ion exchanger-Titanium phosphate towards PB(II),BI(III) and Th(IV)

Abstract

Amorphous titanium phosphate (TiP), an inorganic ion exchanger of the class of tetravalent metal acid (tma) salts has been synthesized by sol-gel method. TiP has been characterized for elemental analysis (ICP-AES), spectral analysis (FT-IR), thermal analysis (TGA and DSC) and X-ray diffraction studies. Chemical resistivity of the material has been assessed in various media-acids, bases and organic solvents. The Na+ ion exchange capacity (IEC) has been determined and the effect of heating on IEC studied. The sorption/ion exchange behaviour of TiP towards Pb(II), Bi(III) and Th(IV) has been studied at different temperatures (313, 323 and 333 K). Kinetic parameters (overall rate constant k?, equilibrium constant Kc, forward and reverse reaction rate constant k1 and k2, respectively) and thermodynamic parameters (standard free energy ?G0, standard enthalpy ?H0, and standard entropy ?S0) have been evaluated and adsorption (Langmuir and Fruendlich) isotherms have been studied. Based on the above studies, the selectivity order is found to be Pb(II) > Th(IV) > Bi(III) at 333 K.