Copper (II) Interactions with Montmorillonite: Evidence from Physical Methods

Abstract Interaction of exchangeable copper(II) with montmorillonite was studied by means of infrared and electron spin resonance spectroscopy supported by X‐ray diffraction, magnetic susceptibility measurements, and determination of CEC values. The solvation properties of the clays after heat treatment are found to be much different with ethanol than with water. Dehydration of exchangeable Cu(II) allows these ions to become imbedded in hexagonal cavities of the silicate structure, or penetrate into the empty octahedral positions and lower the layer charge. Resolvation allow the Cu(II) ions to move out of the hexagonal holes; however, Cu(II) ions that have migrated to the octahedral layer are not exchangeable. No evidence for specific adsorption was found. The results indicate that the properties of Cu(II) on clay surfaces are dependent largely on its strongly held ligand water, and the ion behaves much like other divalent ions on clays.