Alkaline dissolution behavior of montmorillonite under compacted condition

Abstract

  The dissolution rate for montmorillonite under compacted condition was studied in order to evaluate long-term alteration behavior of bentonite buffer materials by highly alkaline groundwater. The dissolution rate of compacted montmorillonite was found to be larger than that of montmorillonite in compacted sand-bentonite mixtures at 130 oC, which revealed that the dissolution of montmorillonite was inhibited by decreasing the activity of hydroxide ions (a_OH^-) in the compacted mixtures including accessory minerals such as silica. In order to provide reliability for the analysis of bentonite alteration using dissolution rate of montmorillonite, it is important to quantify the decrease of a_OH^- in the compacted mixtures and to formulate the dissolution rate of compacted montmorillonite.