Interactions in MX-80 bentonite/water/electrolyte systems

Abstract: The main objective of this work was to study the influence of temperature, water ratio and electrolyte content on the molecular water mobility in water saturated MX-80 bentonite. T a minor extent the influence of pressure, time, and specific surface area on the molecular water mobility was studied. The investigation was carried out by pulsed nuclear magnetic resonance technique, NMR. The proton T2 relaxation time was chosen as a measure of the molecular water mobility. The investigated samples consisted of MX-80 bentonite to which water solutions of either NaCl, KCl, CaCl2, or SrCl2 were added. The electrolyte concentration varied between 0 and 0.35 mol.dm-3. The water ratio varied between 23 and 2000 per cent. The electrolyte content and water ratio were kept within limits corresponding to non-flocculated MX-80 bentonite. The sample temperature varied between +15 and +80° C. The structure of montmorillonite, the main component in MX-80 bentonite, and the structure of liquid water as well as the main physico-chemical interactions taking place in the investigated MX-80 bentonite samples are discussed.