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<p>The safe disposal of high-level radioactive waste relies on a comprehensive understanding of radionuclide migration in deep geological repositories (DGRs). This study investigated the influence of Fe transferred from canister corrosion products into bentonite (WRK) on the sorption–diffusion behavior of radionuclides. To simulate Fe incorporation into bentonite, interlayer Ca<sup>2+</sup> in WRK was substituted with Fe<sup>3+</sup> (Fe(III)-WRK). Physicochemical analyses of Fe(III)-WRK confirmed that Fe<sup>3+</sup> was successfully incorporated into WRK via ion–exchange, without structural alteration. Fe(III)-WRK showed maximum adsorption capacities (<i>q</i><sub>m</sub>) for Sr<sup>2+</sup> (43.4&#xa0;mg/g) and Cs<sup>+</sup> (78.5&#xa0;mg/g) comparable to those of WRK and followed the Langmuir adsorption model. Notably, whereas WRK showed negligible adsorption of I⁻, Fe(III)-WRK exhibited a more positive zeta potential and was able to adsorb I⁻ (<i>q</i><sub>m</sub> = 4.7&#xa0;mg/g). Under simulated groundwater conditions, the adsorption of Sr<sup>2+</sup>, Cs<sup>+</sup>, and I<sup>−</sup> on Fe(III)-WRK was slightly reduced due to competing ions but remained effective. Diffusion experiments further showed that the apparent diffusion coefficient of I⁻ decreased by approximately one order of magnitude in Fe(III)-WRK compared to WRK. These findings indicate that Fe<sup>3+</sup>–exchanged bentonite can enhance anion retention while maintaining cation sorption, thereby potentially improving the long-term performance of bentonite buffer materials in DGR systems.</p>

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Influence of Fe3+‒exchanged bentonite on sorption‒diffusion behavior of Sr2+, Cs+, and I− for high‒level radioactive waste disposal

  • 期刊论文

  • 发表日期：

    2026年3月13日

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  • Hyun-Kyu Lee,
  • Jae-Kwang Lee,
  • Seonggyu Choi,
  • Ja-Young Goo,
  • Sang-Ho Lee,
  • Jang-Soon Kwon

摘要

The safe disposal of high-level radioactive waste relies on a comprehensive understanding of radionuclide migration in deep geological repositories (DGRs). This study investigated the influence of Fe transferred from canister corrosion products into bentonite (WRK) on the sorption–diffusion behavior of radionuclides. To simulate Fe incorporation into bentonite, interlayer Ca2+ in WRK was substituted with Fe3+ (Fe(III)-WRK). Physicochemical analyses of Fe(III)-WRK confirmed that Fe3+ was successfully incorporated into WRK via ion–exchange, without structural alteration. Fe(III)-WRK showed maximum adsorption capacities (qm) for Sr2+ (43.4 mg/g) and Cs+ (78.5 mg/g) comparable to those of WRK and followed the Langmuir adsorption model. Notably, whereas WRK showed negligible adsorption of I⁻, Fe(III)-WRK exhibited a more positive zeta potential and was able to adsorb I⁻ (qm = 4.7 mg/g). Under simulated groundwater conditions, the adsorption of Sr2+, Cs+, and I− on Fe(III)-WRK was slightly reduced due to competing ions but remained effective. Diffusion experiments further showed that the apparent diffusion coefficient of I⁻ decreased by approximately one order of magnitude in Fe(III)-WRK compared to WRK. These findings indicate that Fe3+–exchanged bentonite can enhance anion retention while maintaining cation sorption, thereby potentially improving the long-term performance of bentonite buffer materials in DGR systems.