Cation-exchange properties of iron(III) phosphate

Abstract

Potentiometric titrations of iron(III) phosphate have been carried out in aqueous electrolyte solutions of KCl over the temperature range 299–333 K. The data were explained by the law of mass action. Sorption of Cu²⁺, Zn²⁺, Co²⁺ and Ni²⁺ on iron(III) phosphate was studied over the temperature range 298–323 K. The sorption data fitted the linear from of the Langmuir adsorption equation. Further, the extent of sorption was found to increase with increase in temperature and concentration. The order of selectivity was found to be Cu²⁺ > Zn²⁺ > CO²⁺ > Ni²⁺. The values of the Langmuir constants were used to calculate the thermodynamic parameters: ΔG⁰, ΔH⁰ and ΔS⁰.