Chemisorption of CuII and CoII chlorides and β-diketonates on silica gel functionalized with 3-aminopropyltrimethoxysilane

Silica gel chemically modified with the silylating agent 3-aminopropyltrimethoxysilane (SAPS) adsorbs CuII and CoII in the form of chlorides, acetylacetonates and dipivaloylmethanoates from ethanolic solution. The profiles of the chemisorption isotherms present good correlation with the proposed Langmuir model. The amount of adsorbed species in these chemisorption processes showed that only a fraction of the number of active sites was effectively used by β-diketonates, in comparison with the total available number disposed on the matrix. Based on the equilibrium constant the selectivity of the SAPS matrix with β-diketonates, follows the order CoII>CuII. The chelate of dipivaloylmethanoate with CoII is more pronounced adsorbed on the surface than the correspondent complex of CuII. This fact reveals the possibility of separating both complexes by using this functionalized silica gel surface. However, for chlorides, this modified surface has preference for both cations.