Effects of pH and Concentration on Cs Ions Sorption and Diffusion in Crushed Granite by Using Batch and Modified Capillary Method |
| |
| Authors: | Tsing‐Hai Wang Ming‐Hsu Li Yuan‐Yaw Wei Shi‐Ping Teng |
| |
| Affiliation: | 1. Institute of Nuclear Engineering and Science, National TsingHua University, Hsinchu 300, Taiwan, R.O.C.;2. Institute of Hydrological and Oceanic Sciences, National Central University, Jungli 320, Taiwan, R.O.C.;3. Nuclear Science and Technology Development Center, National TsingHua University, Hsinchu 300, Taiwan, R.O.C.;4. Department of Engineering and System Science, National TsingHua University, Hsinchu 300, Taiwan, R.O.C. |
| |
| Abstract: | ![]()
A comprehensive evaluation of Cs ions sorption to and diffusion in crushed granite was conducted in this study. The sorption capacity of crushed granite suggested by the Langmuir model was 5.48 × 10?6 mol‐Cs/g‐granite. The distribution coefficient (Kd) was around 7.5 mL/g and pH independent. By using an in‐diffusion method with a modified capillary column, some diffusion relevant parameters of Cs ions in crushed granite were derived. The apparent diffusion coefficient (Da) seemed unaffected by Cs concentration (1.15 × 10?10 to 2.82 × 10?10 m2/s, at 10?7 and 10?3 M, respectively). The determined effective diffusion coefficients (De) were located in the window from 8.59 × 10?10 (10?7 M) to 1.69 × 10?9 (10?3 M) m2/s. Under various pH environments, pH independent Da (9.0 × 10?9 m2/s) and De (1.0 × 10?9 m2/s) values were observed. Under current systems, consistently higher De than Da implied the diffusion of Cs ions was governed by surface diffusion phenomenon. Whereas the pH insensitive feature indicated the Cs sorption to crushed granite was mainly through ion‐exchange reaction. Moreover, further SEM/EDS mapping clearly showed the adsorbed Cs ions were highly concentrated on the fracture surface of biotite. |
| |
| Keywords: | Radioactive waste repository Cesium Sorption Diffusion Capillary columns |
|
|
