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

Abstract

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 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 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.