The Co-ordination of Hydrated Cu(II)- and Ni(II)-Ions on Montmorillonite Surface

Firmin Velghe*, Robert A. Schoonheydt and Jan B. Uytterhoeven
Centrum voor Oppervlaktescheikunde en Colloïdale Scheikunde, Katholieke Universiteit Leuven, De Croylaan 42, B-3030 Heverlee, Belgium
* Oleofina, Ertvelde, Belgium.

Abstract: The optical spectra of Cu2+ and Ni2+ on Camp Berteau montmorillonite after lyophilization and evacuation at room temperature are characteristic for the presence of Cu(H2O)42+ and Ni(H2O)62+ in the interlamellar space. The most probable ligand field parameters for Cu(H2O)42+ are Dqxy = 1310 cm−1, Ds = 1807 cm−1 and Dt = 664 cm−1. The covalent character of the Cu2+-OH2 bond is not negligible as indicated by the orbital reduction factors k2 = 0.66 and k2 = 0.76. This is also the case for Ni(H2O)62+ which is characterized by a ligand field strength, Dq = 850 cm−1 and an electronic repulsion parameter B = 920 cm−1. After desorption in vacuum the optical spectra of Cu2+ were poorly resolved, while Ni2+ was present partially as (Ol)3Ni2+, partially as (Ol)3Ni-OH2 where Ol means an oxygen of the hexagonal rings in the tetrahedral layers.

Clays and Clay Minerals; December 1977 v. 25; no. 6; p. 375-380; DOI: 10.1346/CCMN.1977.0250601
© 1977, The Clay Minerals Society
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