Immobilization of metal hexacyanoferrates in chitin beads for cesium sorption: synthesis and characterization

Abstract

International audienc

Organically modified clay with potassium copper hexacyanoferrate for enhanced Cs+ adsorption capacity and selective recovery by flotation

“…The pure organic components completely decomposed as the temperature increased from 200 to 400 o C. For pristine montmorillonite, a small but gradual weight loss is evident at ~700 o C, and this can be attributed to the dihydroxylation of the aluminium-silicate layer and the decomposition of any existing carbonate 33,34 . For pure KCuHCF, the first significant weight loss occurs in the range of 160 to 350 o C, which can be ascribed to both the elimination of coordinating water, this has been widely reported to exist in Prussian blue (PB)-like molecules (< 250 o C) 15,28 , and also the decomposition of the cyano group which has been shown to occur in the range of 250 to 350 o C 15,35 . At higher temperatures it is evident that the intermediate products undergo oxidative decomposition to iron oxides resulting in crystal growth, confirmed by the significant weight loss in the temperature range of 750-800 o C and the corresponding exothermic peak on the DSC curve ( Figure S2b) 36,37 .…”

“…the strong broad adsorption band with a peak at ~1000 cm -1 corresponds to the Si-O vibration of the tetrahedral silica sheet 27 . In the sample of organo-clay (Mont-EH-DT), the C-H stretching vibration peaks between 2750 cm -1 and 3000 cm -1 , and the CH2 bending vibration at 1470 cm -1 are assigned to the methylene moiety 15,23 Figure 3b). From the C 1s deconvolution spectrum in Figure 3c, two peaks centered at 283.92 eV and 285.69 eV were identifiable, which corresponded to the matrix C-C/C-H peaks and a C N group respectively 28 .…”

“…As is known, alkyldiamine chelates to a wide assortment of transition metal cations 19 , making the ligand a useful chelating agent to build different metal-ferrocyanides. Copper-ferrocyanide was chosen in the current study because of its high Cs + recovery 15 . ii) Copper chelation with the montmorillonite particles.…”

“…An alternative group of adsorbents that are cost-effective and show high adsorption capacity are Prussian blue analogues (PBAs), namely the hexacyanoferrates (HCFs) of transition metals, wherein potassium copper hexacyanoferrate (KCuHCF) provides higher Cs + selectivity compared to other metal hexacyanoferrates 15 . Hexacyanoferrate(II) is an agent of high Cs + affinity and selectivity, with the small hydrated ions such as Cs + able to permeate through the cubic structure, while the larger competing ions are blocked from accessing the sorption sites [15][16][17][18] .…”

“…Hexacyanoferrate(II) is an agent of high Cs + affinity and selectivity, with the small hydrated ions such as Cs + able to permeate through the cubic structure, while the larger competing ions are blocked from accessing the sorption sites [15][16][17][18] . However, the fine particle size of this type of adsorbent makes it difficult to separate from aqueous environments, so it is generally incorporated within supporting materials for effective Cs + adsorption and removal 15,19 . The main supporting materials are either polymer composites or mesoporous silica, both of which show limited Cs + adsorption capacity.…”