Selective and effective removal of cesium ions using Prussian blue analog@γ-alumina core-shell pellets

The removal of cesium-137 ( 137 Cs) from nuclear wastewater remains crucial due to its radioactivity and high solubility in water, which pose serious risk to human health and the environment. Aiming at selective capture of Cs + from wastewater, a core-shell adsorbent, Prussian blue analog@γ-alumina (PBA@Al 2 O 3 ) pellets were synthesized using the hydrothermal-stepwise deposition method. The core-shell PBA@Al 2 O 3 pellets showcased a PBA loading of 25% and demonstrated a maximum adsorption capacity of 15.65 mg·g −1 . The adsorption data was consistent with the pseudo-second-order kinetic model and the Langmuir isotherm model. It effectively reduced bulk Cs + concentrations from an initial 6.62 mg·L −1 to 2 μg·L −1 , achieving a removal efficiency of 99.97% and distribution coefficient ( K d ) of 1.265 × 10 6 ml·g −1 , surpassing the performance of other PBA-based materials. The material also indicated good mechanical properties and cesium ion removal rates of 99.7% across a wide pH range (1.82 to 11.12). Furthermore, PBA@Al 2 O 3 exhibited consistent removal rate of over 99% and good selectivity (SF = 50–1600) towards Cs + even in the presence of interfering ions such as Na + , K + , Mg 2+ , and Ca 2+ ions. The K d (Cs + ) for PBA@Al 2 O 3 in simulated seawater and groundwater were 9.92 × 10 3 and 2.23 × 10 4 ml·g −1 , where the removal rates reached 96.1% and 98.2%, respectively. XPS confirms that the adsorption mechanism is the ion exchange between Cs + and K + ions. This study underscores the significant potential of inorganic core-shell pellets adsorbents as promising agents for the selective capture of Cs + from wastewater.