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-aminopropyltrime thoxysilane (SAPS) adsorbs Cu-II and Co-II in the form of chlorides, acetyl acetonates and dipivaloylmethanoates from ethanolic solution. The profiles of the chemisorption isotherms present good correlation with the proposed L angmuir model. The amount of adsorbed species in these chemisorption proces ses showed that only a fraction of the number of active sites was effective ly used by beta-diketonates, in comparison with the total available number disposed on the matrix. Based on the equilibrium constant the selectivity o f 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 silic a gel surface. However, for chlorides, this modified surface has preference for both cations. (C) 2000 Elsevier Science B.V. All rights reserved.