Chemisorption of Cu-II and Co-II chlorides and beta-diketonates on silica gel functionalized with 3-aminopropyltrimethoxysilane

Silica gel chemically modified with the silylating agent 3-aminopropyltrimethoxysilane (SAPS) adsorbs Cu-II and Co-II 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 beta-diketonates, in comparison with the total available number disposed on the matrix. Based on the equilibrium constant the selectivity of the SAPS matrix with beta-diketonates, follows the order Co-II>Cu-II. The chelate of dipivaloylmethanoate with Co-II is more pronounced adsorbed on the surface than the correspondent complex of Cu-II. 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. (C) 2000 Elsevier Science B.V. All rights reserved.16641699455