Decommissioning Technology Research Division, Korea Atomic Energy Research Institute, 989-111, Daedeokdae-ro, Yuseong-gu, Daejeon, 34057, Republic of Korea.
Department of Chemical Engineering and Applied Chemistry, College of Engineering, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon, 34134, Republic of Korea.
Environ Sci Pollut Res Int. 2020 Oct;27(28):35580-35590. doi: 10.1007/s11356-020-09675-3. Epub 2020 Jun 27.
The desorption of radioactive cesium (Cs) in soil is influenced by the clay mineral type, adsorption site, and concentration of Cs. In this study, experiments to detect desorption of non-radioactive and radioactive Cs from illite using oxalic acid were performed for 2 days at 70 °C in hydrothermal conditions. The results showed that the Cs removal efficiency by oxalic acid and inorganic acid treatment was similar at high concentration (22.86 mmol/kg) of non-radioactive Cs. In the radioactive Cs experiment, the removal efficiency by oxalic acid was higher than that by inorganic acid at low concentration (0.79 × 10 mmol/kg) of radioactive Cs. Based on the illite hypothetical frayed edge site (FES) concentration of 0.612 mmol/kg, the results suggested that Cs was preferentially adsorbed to FES on illite. The Cs at low concentration was difficult to remove because it was irreversible adsorption to FES, while the non-radioactive Cs at high concentration was mainly adsorbed to planar sites, and so was easy to desorb by ion exchange. Based on the results of NMR, FTIR, and XPS analyses, we concluded that the higher efficiency of Cs removal at low concentration by oxalic acid treatment than by treatment with inorganic acid was because of chelation effects associated with the complexation of oxalic acid (ligands) and metal ions in irreversible site (FES).
土壤中放射性铯（Cs）的解吸受粘土矿物类型、吸附位和 Cs 浓度的影响。在这项研究中，在 70°C 的水热条件下，使用草酸对伊利石中非放射性和放射性 Cs 的解吸进行了为期 2 天的实验。结果表明，在高浓度（22.86 mmol/kg）非放射性 Cs 下，草酸和无机酸处理的 Cs 去除效率相似。在放射性 Cs 实验中，在低浓度（0.79×10 mmol/kg）放射性 Cs 下，草酸的去除效率高于无机酸。基于伊利石假设的磨损边缘位点（FES）浓度为 0.612 mmol/kg，结果表明 Cs 优先被吸附到伊利石上的 FES。低浓度的 Cs 难以去除，因为它是对 FES 的不可逆吸附，而高浓度的非放射性 Cs 主要被吸附到平面位点，因此容易通过离子交换解吸。基于 NMR、FTIR 和 XPS 分析的结果，我们得出结论，低浓度下草酸处理的 Cs 去除效率高于无机酸处理，这是因为草酸（配体）与不可逆位点（FES）中金属离子的螯合效应。
