Linking the multiscale porous structure of hexacyanoferrate-loaded silica monoliths to their hydrodynamic and cesium sorption properties

• Published in: Separation and purification technology 2019-12, Vol.229 (C), p.115796, Article 115796
• Main Authors: Cabaud, Clément, Barré, Yves, De Windt, Laurent, Grandjean, Agnès
• Format: Article
• Language: English
• Subjects: Column process; Earth Sciences; Ferrocyanide; Geochemistry; Hierarchical material; HYTEC; Ion exchanger; nuclear, materials and chemistry by design, synthesis (novel materials), synthesis (predictive); Sciences of the Universe
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2019.115796

•Monolithic and powder forms of functionalized silica are compared for Cs removal.•Reactive transport modeling is used to fit and interpret experimental data.•The monolithic structure sustains high flow rates with sharp breakthrough front.•The high selectivity and fast kinetics come from accessible HCF particles.•The modeling approach can be extrapolated to various multiscale sorbents. Multiscale porous silica monoliths functionalized with potassium/copper hexacyanoferrate (HCF) have been evaluated for the column extraction of cesium from natural water. Compared with commercial silica gel particles, results show that the hierarchically porous architecture of the monoliths improves the bed efficiency in column extraction, and the selectivity, distribution coefficient and exchange kinetics in batch extraction. Cesium breakthrough experiments show that these preferable properties of the monolithic structure are maintained in column operation. This analysis of the batch and breakthrough experiments is supported by scanning and transmission electron microscopy data, residence time distributions, and reactive transport modeling assuming dispersive flow in the macroporous intraskeletal channels and diffusion inside the walls of the structure and the HCF aggregates.