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 ¹³³Cs removal efficiency by oxalic acid and inorganic acid treatment was similar at high concentration (22.86 mmol/kg) of non-radioactive ¹³³Cs. In the radioactive ¹³⁷Cs experiment, the removal efficiency by oxalic acid was higher than that by inorganic acid at low concentration (0.79 × 10⁻⁶ mmol/kg) of radioactive ¹³⁷Cs. Based on the illite hypothetical frayed edge site (FES) concentration of 0.612 mmol/kg, the results suggested that ¹³⁷Cs was preferentially adsorbed to FES on illite. The ¹³⁷Cs 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 ¹³⁷Cs 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、吸附位点和 Cs 浓度的影响。在这项研究中，在 70 °C 的水热条件下进行了 2 天的实验，以检测使用草酸从伊利石中解吸非放射性和放射性 Cs。结果表明，在高浓度（22.86 mmol/kg）非放射性¹³³ Cs 下，草酸和无机酸处理对¹³³ Cs 的去除效率相似。在放射性¹³⁷ Cs 实验中，草酸对低浓度（0.79 × 10 ^-6  mmol/kg）放射性¹³⁷的去除效率高于无机酸CS。基于 0.612 mmol/kg 的伊利石假设磨损边缘位点 (FES) 浓度，结果表明¹³⁷ Cs 优先吸附到伊利石上的 FES。低浓度的¹³⁷ Cs 难以去除，因为它对 FES 不可逆吸附，而高浓度的非放射性 Cs 主要吸附在平面位点，因此易于通过离子交换解吸。基于 NMR、FTIR 和 XPS 分析的结果，我们得出结论，草酸处理在低浓度下的¹³⁷ Cs 去除效率高于无机酸处理，这是因为与草酸（配体）络合相关的螯合效应) 和不可逆位点 (FES) 的金属离子。