Unveiling Cs-adsorption mechanism of Prussian blue analogs: Cs⁺-percolation via vacancies to complete dehydrated state

Abstract

Cs+ adsorption selectivity caused by hydration energy and percolation theory to evaluate the ion-exchangeable site ratio.

Interpretation of the Role of Composition on the Inclusion Efficiency of Monovalent Cations into Cobalt Hexacyanoferrate

“…In general, three states of water can be considered in the NaCoHCF crystal, Figure b: water molecules can exist freely in the interstitial sites, as H 2 O–Na pairs, and as water coordinated to Co in the lattice. However, the relationship between x , y , and z in NaCoHCF is different from that observed in CuHCF . The main reason for this deviation could be the presence of Co, as it can be stable in both five‐ and six‐coordinated states, which means the existence of fewer water molecules can be due to the presence of five‐coordinated Co …”

“…However, as shown in Figure , the trend of adsorption of monovalent cations is variable. It has already explained that although the hydrated ionic radii of NH 4 (3.31 Å), K (3.31 Å), and Cs (3.29 Å) are not vastly different, their dehydrated size plays a role as they are found to lose the water of hydration during adsorption . The larger Cs ion could not exchange with Na ions in the low vacancy region.…”

“…NH 4 , however, could proportionally replace Na until the vacancy decreased to 0.19. As explained in the previous work, larger ions like Cs could use the inner available spaces in the adsorbent material by percolation via the vacancies (PVV). Therefore, when the lattice becomes more compact, the percolation process becomes slower.…”

Towards the Extraction of Radioactive Cesium-137 from Water via Graphene/CNT and Nanostructured Prussian Blue Hybrid Nanocomposites: A Review

“…On the other hand, water soluble analogs such as metal hexacyanoferrates (HCF) consisting of a alkali metal cation with a [Fe +2 (CN) 6 ] anion, used for the extraction of 137 Cs + have shown less efficiency. In such compounds Na + or K + are incorporated during the synthesis of the MOF in order to render them water-soluble [31]. In addition to 137 Cs + capture mechanisms for non-soluble analogs; the water-soluble analogs mainly depend on the Na + or K + ion exchanges with Cs + .…”

“…In addition to 137 Cs + capture mechanisms for non-soluble analogs; the water-soluble analogs mainly depend on the Na + or K + ion exchanges with Cs + . Takahashi et al, have studied the 137 Cs + uptake in KCuHCF PB analog in order to understand their lower adsorption capacity [31]. Three main mechanisms governed the 137 Cs + ion exchange according to them, with the 137 Cs + -K + ion exchanges being predominant, as also stipulated by other research groups.…”