Nanocrystalline Ce(OH)${}_4$-based materials. Ruthenium selective adsorbent for highly alkaline radioactive liquid waste

Cerium hydroxide, Ce(OH)${}_4$ (Ce), has been synthesised and assessed as a Ru-selective adsorbent for treating alkaline radioactive liquid waste. Infrared spectroscopy, thermal analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy investigations confirmed the successful formation of nanocrystalline Ce from Ce(NO${}_3$)${}_3$·6H${}_2$O. Selective removal of ${}^{106}$Ru from the ion-exchange effluent of intermediate-level liquid waste (ILW) by Ce was assessed using a high-pure germanium (HPGe) gamma-ray spectrometer. The calculated average distribution coefficient (k${}_D$) was ∼200 mL/g. The percentage removal of ${}^{106}$Ru using Ce by varying time, [${}^{106}$Ru] and [Ce] was calculated. The adsorption of ${}^{106}$Ru on Ce follows pseudo-second-order and Freundlich isotherms. The calculated Q${}_{max}$ was 93,584 Bq/g. Accelerated leaching studies of the Ru-laden Ce cement product were carried out and found suitable for transport and disposal. Further, Ce-Polyether sulphone (Ce-PES) and Ce-Chitosan (CeC) composites were prepared and assessed for their Ru-uptake capacity for engineering scale application.