Effect of 1,4-Dioxane on the Expansion of Montmorillonite Layers in Montmorillonite/Water Systems1

Jun Wu2, P. F. Low and C. B. Roth
Agronomy Department, Purdue University, West Lafayette, Indiana 47907
1 Journal Paper 13596, Purdue University Agricultural Research program, West Lafayette, Indiana 47907-1150.
2 Visiting Associate Professor from the Institute of Soil Science, Academia Sinica, Nanjing, People's Republic of China.

Abstract: Suspensions were produced by mixing Na-saturated, Upton montmorillonite with aqueous solutions containing different concentrations of 1,4-dioxane. Each suspension was deposited on a porous ceramic filter in an environmental chamber, and the solution was expressed from it by admitting gaseous helium to the chamber at a slightly elevated pressure. The chamber was fitted 1) with beryllium windows so that X-rays could be transmitted into and out of it and 2) with a drain so that the expressed solution could be conducted to the outside atmosphere. Once a filter cake had formed on the filter, the pressure of the gaseous helium was raised in successive increments and, after each increment, the c-axis layer spacing(s) was determined by X-ray diffraction. Increasing the concentration of 1,4-dioxane caused some of the fully expanded layers to collapse to the partially expanded state (c-axis spacing = 15 Å) and appeared to cause the remaining fully expanded layers to move farther apart, especially at the higher pressures. Alternative explanations were given for these apparently contradictory results.

Key Words: 1,4-dioxane • Layer expansion • Montmorillonite • Swelling

Clays and Clay Minerals; April 1994 v. 42; no. 2; p. 109-113; DOI: 10.1346/CCMN.1994.0420201
© 1994, The Clay Minerals Society
Clay Minerals Society (www.clays.org)