STUDY ON THE COMPLEX FORMATION BETWEEN N-PROPYLSALICYLIDENE BASED ON SILICA AS ION EXCHANGER AND SOME TRANSITION METAL IONS

Abstract

N-propylsalicylidene based on silica as ion exchanger (IE) was used for the separation by complexation of Mn2+, Co2+, Ni2+, Cu2+, Hg2+, Cr3+, Fe3+, and UO22+ from their parent solutions. IE and its metal complexes are characterized by elemental analysis, electronic and infrared spectra, in addition to thermal analysis in atmospheric pressure. The mode of chelation and the proposed geometric structures of the metal complexes of IE are suggested by infrared and electronic spectra, respectively. Elemental and thermal analysis indicate that the percentage of the organic content increased from IE-Cr (5.409) to IE-Hg (13.5) with respect to that of IE (13.655) owing to the catalytic effect of these metal ions. Three different stages of decomposition have been accompanied by the thermal degradation of IE and IE-metal complexes. These stages were found to be affected by the presence of the investigated metal ion. By application of non-isothermal kinetic equation, the activiation energy (Ea) for the IE and its complexes was calculated. Ea follows the order, IE-Fe < IE-Co < IE < IE-Mn < IE-UO2 < IE-Cr < IE-Ni < IE-Cu < IE-Hg. The thermodynamic parameters Ea, ?H°, ?S° and ?G° of the obtained complexes were found to be largely dependant on the electronegativity of the studied metal ions.