Factors affecting the interparticle bond energy of sodium-montmorillonite

This thesis reports the results of four different investigations in chapters entitled (1) Factors affecting the interparticle bond energy of Na-montmorillonite; (2) Effect of organic compounds on the interparticle bond energy of Na-montmorillonite; (3) Heats of immersion of silicon and aluminum oxides and clays; and (4) Relation between the swelling and spectroscopic properties of soil clays, respectively. The interparticle bond energy was measured by a visco-calorimetric technique involving a Stormer viscometer and a Calvet calorimeter, the heat of immersion was measured by the Calvet calorimeter, the swelling by a pressure-membrane device and the spectroscopic properties by a Perker-Elmer (Model 1800) FTIR spectrometer. It was found that the interparticle bond energy was quite large and increased with clay concentration, fell to a minimum and then rose to a maximum with the concentration of inorganic or organic electrolytes, decreased with the concentration of neutral organic solutes and exhibited essentially no change with pH. Further, it was found that the heat of immersion depended linearly on the specific surface area only for spherical, uncharged oxides and silicates and that the selling pressure of soil clays was highly correlated with the spectroscopic properties of the water within them. From these findings we concluded that: (1) many factors affect interparticle bonding, (2) that some of these factors exert their effect by modifying the interparticle water, (3) in-depth hydration of the particle surfaces makes a significant contribution to the heat of immersion and amounts to $\sim$0.15 J/m$\sp2$, (4) the energy required to separate the particles reduces the heat of immersion significantly, especially for planar particles, (5) the surfaces of talc and pyrophyllite are hydrophyllic and some of them separate during immersion in water, and (6) the swelling of soil clays is largely due to modification of the interparticle water by the particle surfaces.