Clay Minerals (1975), 10, 357. SURFACE PROPERTIES OF MIXED Cu ( I I)-- TETRAALKYLAMMONIUM MONTMORILLONITES

ABSTRACT: Initial exchange of Cu(II)-montmorillonite by tetrapropylammonium (TPA) or tetramethylammonium (TMA) ions results in segregation of different ions in randomly interstratified layers, with particular preference for TPA over Cu(II) during exchange. More complete xchange reverses this preference and both Cu(II)-TPA and Cu(II)-TMA clays become more homogeneous. The copper ions of the homo-geneous Cu(II)-TPA clays are not fully hydrated while the TMA ions have less effect than TPA on the hydration of copper, probably aresult of the smaller adius and higher hydration energy of TMA. Methods of X-ray diffraction, thermogravimetric analysis, BET surface area determinations, as well as infrared and electron spin resonance spectroscopy, are used in supplying evidence of cation distribution and hydration properties of these clays. Definite changes in the properties of hydrated copper when associated with tetraalkylammonium ions on the clay surface are indicated