Jeonghwan Hwang1·Sungwook Choung2·Weon Shik Han1*·Wonwoo Yoon1
1Department of Earth System Sciences, Yonsei University, Seoul 03722, Republic of Korea
2Research Center for Geochronology and Isotope Analysis, Korea Basic Science Institute (KBSI),
Cheongju 28119, Republic of Korea
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This study investigated the mineralogical properties of bentonite and illite and evaluated the Cs sorption at various concentrations (Cw≈1–105 μg/L). Bentonite samples, collected from South Korea and USA, majorly consisted of Ca- and Na-montmorillonite, showed large cation exchange capacity (CEC, 91.4 and 47.3 meq/100 g) and specific surface area (SSA, 46.1 and 39.7 m2/g). In contrast, illite sample (USA) had relatively low values for 14.4 meq/100g of CEC and 29.3 m2/g of SSA, respectively. Bentonite and illite had different non-linear sorption for Cs along with Cw. At low Cw<10 μg/L, illite showed higher sorption capacity than bentonite despite low CEC because of the existence of specific sorption sites at the weathered mineral edge. However, as Cw increased, bentonite represented high sorption capacity because the cation exchange between Cs and interlayer cations was effective at high Cw conditions. These results implicated that the Cs concentration is important to evaluate the sorption performance of bentonite and illite. Finally, the Cuadros’ kinetic model for illitization using various K concentrations (2×10–5 and 1.7×10–3 mol/L) and temperature (100–200oC) showed that up to 50% of the montmorillonite in bentonite could be converted to illite, suggesting that the illitization should be considered to evaluate the sorption performance of the bentonite in deep geological disposal repository.
Keywords: Bentonite, Illite, Sorption, Cesium, Deep geological disposal repository
2021; 26(5): 29-38
Published on Oct 31, 2021
Department of Earth System Sciences, Yonsei University, Seoul 03722, Republic of Korea