Themodynamic Study of Metal Ions Complexes With Poly(Hydroxamic Acid) Ion Exchage Resin

M. R. Lutfor¹, S. Silong², M. Ahmad², M. Z. A. Rahman², M. J. Haron², W. M. Z. Wan Yunus²

¹School of Science and Technology, Unirversiti Malaysia Sabah, Locked Bag 2073, 88999 Kota Kinabalu, Sabah, (Malaysia) ²Department of Chemistry, FSAS, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, (Malaysia)

The ion exchane isotherm of transition metal ions in binary mixture of Cu2+ -Na+,Ni2+ -Na+, Co2+ - Na+,Cd2-Na+ systems were studied on the poly (hydroxamic acid) ion exchange resin with forward and backward reaction of ionic strenght of 0.1. It was observed that the selectivity coefficients varied with the external metal ion concentration i.e. the selectivity decreases with the increases of total metal ions solution concentration. The thermodynamic equilibrium constant (K), standard Gibbs free energy (DG°), standard enthalpy (DH°) and entropy (DS°) were calculated from exchange isotherms. The DG° were negative for all bivalent M2 -Na2 exchage system. The DH° and DS° chages in the exchange system of the ion exchange isotherm were positive for Cu2+,Ni2+ and negative for Co2+ and Cd2+ respectively. From the exchange isotherm the thermodynamic affinity sequences were obtained with some transition metal ions, which indicated the strong affinity for Cu2+ and Ni2+ on the poly (hydroxamic acid) resin.

Poly (hydroxamic acid); Ion-exchange; Thermodynamic study; Selectivety coefficient; Equilibrium contant; Free energy; Enthalpy; Entropy