Exchange Character of Caesium Ions onto Zirconium Tungstate

Abstract

Amorphous zirconium tungstate, an inorganic ion-exchanger, was synthesized under optimum conditions and used as a cation-exchange material for the removal of caesium ions from radioactive waste solutions under simulated conditions using batch techniques. The physical and chemical properties of the synthesized ion-exchanger were characterized using Fouriertransform (FT) infrared, X-ray diffraction (XRD) and differential scanning calorimetric (DSC) techniques. Its chemical stability in various mineral acids, bases and organic solvents was also assessed. The data obtained reveal that the prepared exchanger had a good ionexchange capacity (1.34 mequiv/g towards Cs+ ions) and a high thermal and chemical stability. A hypothetical structural formula, Zr[WO2(OH)2]• 4H2O, was proposed on the basis of chemical composition, FT-IR and thermal analyses. The influences of pH, contact time, initial solute concentration and temperature are reported. Various parameters such as the effective diffusion coefficient under different conditions and the activation energy were determined from the graphical representation of the linearized form of the Arrhenius equation. Thermodynamic parameters such as ΔG0, ΔH0 and ΔS0 were also calculated. The numerical value of ΔG0 increased from 7.43 to 9.74 kJ/mol as the temperature was increased from 298 K to 313 K, indicating that the exchange reaction was more favourable at low temperatures. The negative value of ΔH0 (–49.55 kJ/mol) reflected the exothermic nature of the exchange process.

A highly hydrophilic water-insoluble nanofiber composite as an efficient and easily-handleable adsorbent for the rapid adsorption of cesium from radioactive wastewater

“…28 Apart from the 35 characteristic absorption band, there are two significant changes in the FT-IR peaks (-OH and -C-O-C-) obviously confirm the cross-linking of PVA with GA. 29 In the FI-IR spectrum of cPBNPs/PVA composites nanofibers, the intensity of the adsorption peak at 3300 cm -1 (-OH stretching) decreased and 40 simultaneously the adsorption peak at 1150-1085 cm -1 (-C-O-Cstretching) increased when compared with that of the uncrosslinked nanocomposite nanofibers (PVA/PBNPs/GA). These results confirm that the -OH groups in the PVA and the -CHO groups in GA typically reacted to form an acetal groups or ether 45 linkages during the cross-linking process (Fig. 6c).…”

“…A high-voltage power supply (Har-100*12, Matsusada Co., Tokyo, Japan), capable of generating voltages up to 100 kV, was 45 used as the source of the electric field. The above obtained PVA/PBNPs/GA solutions were poured in a 5 mL plastic syringe attached to a capillary tip of about 0.6 mm in inner diameter.…”

“…9,13,14 At present, the challenging task is the development of easily separable Cs 95 adsorbents. 45 There are several reports describe various separation techniques for the removal Cs adsorbents after treatment. However, since the PBNPs-based nanocomposites are very small in size (10-100 nm), the separation process is more complicated and expensive.…”

“…7 Interestingly, due to the high specific surface area, the PBNPs has showed an excellent adsorption efficiency of Cs (about 100%). 8 However, since the size of the PBNPs is too small, the recovery of the PBNPs (after the adsorption of Cs) is very 45 complicated which causes more problems to the living organisms and the environment. 9 Reda et al, 10 has prepared magnetic hexacyanoferrate(II) polymeric nanocomposite for the separation of Cs from radioactive wastewater.…”

Synthesis and characterization of magnetic hexacyanoferrate (II) polymeric nanocomposite for separation of cesium from radioactive waste solutions

“…The major contaminants of these wastes are fission products and actinides. The recovery of valuable elements, lanthanides, and actinides from high level nuclear wastes is an area of worldwide concern [1,2]. Among the main fission products released, cesium radioisotopes stand as the most important fission products because of their high fission yield, long half-life ( 137 Cs (T 1/2 $ 30.17 year), 135 Cs (T 1/2 $ 2.3 Â 10 6 year), 134 Cs (T 1/2 $ 2.06 year)) and serious environmental impacts [3].…”