Adsorption of Rubidium/Cesium From Aqueous Solution Using Silane-Modified Prussian Blue-Based Composites

This study presents the synthesis and application of a novel silane-modified Prussian blue-based composite (PB-Si) adsorbent for the efficient extraction of rubidium and cesium ions from aqueous solutions. The PB-Si adsorbent is synthesized using the Pickering high internal phase emulsions polymerization method, which leverages the stability of Pickering emulsions formed by nanoparticles at the interface of two immiscible solutions. The modification of Prussian blue with 3-aminopropyl trimethoxy silane enhances the hydrophilicity and stability of the adsorbent. Adsorption kinetics and isotherms results reveal that the PB-Si adsorbent achieves rapid adsorption equilibrium within 2.5-3 h. The PB-Si adsorbent exhibits high adsorption capacities of 317.4 mg/g for Rb⁺ and 402.6 mg/g for Cs⁺. In addition, the developed adsorbent retains 88.3% and 91.7% of its initial adsorption capacity for Rb⁺ and Cs⁺, respectively, after five consecutive adsorption-desorption cycles. The investigation into the adsorption mechanism indicates that chemisorption, driven by electrostatic attraction and chemical complexation with functional groups (─COO^-) on the surface of the adsorbent, is the dominant process. This study highlights the potential of the PB-Si composite adsorbent as an effective and regenerable material for the extraction of Rb⁺ and Cs⁺ from aqueous solutions, with implications for environmental remediation and resource recovery.