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<p>As the key buffer material in deep geological repositories for high-level radioactive waste, bentonite experiences chemical interactions with alkaline solutions resulting from cement degradation during long-term repository operation. This study investigated the effect of alkaline solutions on GMZ bentonite through a self-designed diffusion experiment using NaOH and KOH solutions (pH 12–13.8). The results showed that some compositions of bentonite such as montmorillonite, quartz, and albite, were partly dissolved after a one-year test. While both alkaline solutions showed similar effects on bentonite, the KOH solution dissolved more montmorillonite and promoted the formation of illite. Ion exchange reactions between bentonite and alkaline solutions are evident at pH &gt; 12.6, accompanied by reduced montmorillonite interlayer spacing. Microstructural characterization revealed that the montmorillonite interlayer collapsed under elevated pH conditions, generating some micro-cracks and holes that accelerate the mineral dissolution.</p>

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Degradation of GMZ bentonite by diffusion of alkaline solutions with various pH

  • 期刊论文

  • 发表日期：

    2025年12月12日

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  • Yanmei Tong,
  • Huyuan Zhang,
  • Quanquan Jia,
  • Xueting Li,
  • Ying Wang

摘要

As the key buffer material in deep geological repositories for high-level radioactive waste, bentonite experiences chemical interactions with alkaline solutions resulting from cement degradation during long-term repository operation. This study investigated the effect of alkaline solutions on GMZ bentonite through a self-designed diffusion experiment using NaOH and KOH solutions (pH 12–13.8). The results showed that some compositions of bentonite such as montmorillonite, quartz, and albite, were partly dissolved after a one-year test. While both alkaline solutions showed similar effects on bentonite, the KOH solution dissolved more montmorillonite and promoted the formation of illite. Ion exchange reactions between bentonite and alkaline solutions are evident at pH > 12.6, accompanied by reduced montmorillonite interlayer spacing. Microstructural characterization revealed that the montmorillonite interlayer collapsed under elevated pH conditions, generating some micro-cracks and holes that accelerate the mineral dissolution.