Chiang Mai Journal of Science

     Adsorption is one of the effective methods used for the removal of contaminants from radioactive wastewater. In this research, removal efficiency of Cs from the prepared low-concentration Cs solution (100 μg/L) was studied using two different adsorbents namely high purity Kunipia-F bentonite and Silicon dioxide (SiO₂). After performing the adsorption tests, the Cs ions in liquid and solid phases were analyzed using the inductively coupled plasma mass spectrometry (ICP-MS) technique. The adsorption capacities of both materials were then compared. It was found that the Cs adsorption capacity of bentonite was higher than that of SiO₂. The distribution coefficient of Cs in the bentonite was 1.0 L-sol/g-solid, which was 100 times greater than that of SiO₂. The highest sorption of Cs on bentonite could be attributed to its smaller particle size (0.362 μm), compared to the SiO₂ particle size (0.625 μm). Bentonite is natural clay and is generally used as a buffer material in geological disposal systems for high-level nuclear waste. The results of this research indicate that bentonite could be an effective absorbent for decontaminating low concentration Cs in radioactive wastewater.