Self-propelling shuttles for radioactive caesium adsorption

Abstract

Nuclear accidents such as the events at the Fukushima Daiichi nuclear power plant in 2011 require a rapid response to minimise contaminant release. Self-propelling shuttles functionalised with Prussian blue are developed for radioactive caesium (Cs) removal from aqueous phases during accident and emergency scenarios. The Marangoni effect provides thrust to the shuttle via ethanol diffusion from an infused hydrogel housed in the shuttle, achieving self-motion for 20–30 minutes with a peak velocity of 1.2 cm s⁻¹. Cs adsorption efficiency by the self-propelling shuttles (83.9%) was comparable after 30 minutes to stirred systems containing a dormant shuttle (85.6%), indicating that the self-propelling property is effective. A maximum loading capacity was estimated at 106 mg g⁻¹ (Langmuir, adj. R² – 0.99) based on adsorption isotherms, with pseudo-second-order kinetics (R² = 0.98) best describing the rate-limiting adsorption step as chemisorption. Cs adsorption and subsequent recovery of the shuttles enabled the effective removal of ¹³⁷Cs from solution (91%).