Ion Exchange Equilibrium of K(I), Rb(I) & Cs(I) Ions on Phosphonated Toluene- Phenol-Formaldehyde Cation Exchange Resin (Na+-form)

Abstract

Equilibrium exchange studies of K⁺/Na⁺, Rb⁺/Na⁺ and Cs⁺/Na⁺ systems on phosphonated toluene-phenolformaldehyde cation exchange resin (Na⁺-form) have been made in pure water at different ionic strengths (0.025, 0.05 and 0.1<em>M</em>) and at different <em>p</em>H values. Activity coefficients of the ions have been obtained. The rational thermodynamic equilibrium constants are found to be dependent on temperature and <em>p</em>H of the medium. Interestingly the order of affinities at <em>p</em>H values 6.9 and 9.0 (Cs⁺&gt; Rb⁺ &gt; K⁺ &gt; Na⁺) is reversed at <em>p</em>H values 11.6 and 13.6. The thermodynamic functions <img src='http://www.niscair.res.in/jinfo/delta.gif' border=0><em>H</em>ᵒ<em>, </em><img src='http://www.niscair.res.in/jinfo/delta.gif' border=0><em>G</em>ᵒ and <img src='http://www.niscair.res.in/jinfo/delta.gif' border=0><em>S</em>ᵒ for the exchange reactions have been evaluated. The characteristic maximum water uptake of the-resin in various ionic forms has also been calculated.