Published online by Cambridge University Press: 28 February 2024
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.
Journal Paper 13596, Purdue University Agricultural Research Program, West Lafayette, Indiana 47907-1150.
Visiting Associate Professor from the Institute of Soil Science, Academia Sinica, Nanjing, People's Republic of China.