• Journal of the Korean institute of surface engineering
• /
• v.21 no.1
• /
• pp.47-52
• /
• 1988

The purpose of th this study was to determine an adsorption capaty of cesium by domestic zeolite, clinoptilolite, which has adsorption selectivity and resistence to radiolytic degradation, and to find the operation of column packed natural or Na cinoptiloite. The exchange capacity of cesium was 0, 875 m eq-per gram of clinopilolite. Na clinoptilolite was mire effective for cesium removal than naturl clioptilolite. Then, the results show that the domestic cilnoptilolite activated with sodium hydroxide colud be applicable for removal of cesium from liquid radwastes.

• Bulletin of the Korean Chemical Society
• /
• v.22 no.12
• /
• pp.1345-1349
• /
• 2001

New quadruply-bridged calix[6]arenes (I-V) have been studied as cesium selective ionophores in poly(vinyl chloride) (PVC) membrane electrodes. PVC membranes were prepared with dioctyl sebacate (DOS) or 2-nitrophenyl octyl ether (o-NPOE) as the sol vent mediator and potassium tetrakis(p-chlorophenyl)borate as the lipophilic salt additive. These ionophores produced electrodes with near-Nernstian slope. The selectivity coefficients for cesium ion with respect to alkali, alkaline earth and ammonium ions have been determined. The lowest detection limit (logaCs+ = -6.3) and the higher selectivity coefficient (logkpotCs+,Rb+ = -2.1 by SSM, -2.3 by FIM for calix[6]arene I) for Cs+ have been obtained for membranes containing quadruply-bridged calix[6]arenes (I, Ⅱ, Ⅲ), which have no para t-butyl substituents on the bridging benzene ring.

• Nuclear Engineering and Technology
• /
• v.52 no.2
• /
• pp.328-336
• /
• 2020

Cesium is a major product of uranium fission, which is the most commonly existed radionuclide in radioactive wastes. Various technologies have been applied to separate radioactive cesium from radioactive wastes, such as chemical precipitation, solvent extraction, membrane separation and adsorption. Crown ethers and calixarenes derivatives can selectively coordinate with cesium ions by ion-dipole interaction or cation-π interaction, which are promising extractants for cesium ions due to their promising coordinating structure. This review systematically summarized and analyzed the recent advances in the crown ethers and calixarenes derivatives for cesium separation, especially focusing on the adsorbents based on extractants for cesium removal from aqueous solution, such as the grafting coordinating groups (e.g. crown ether and calixarenes) and coordinating polymers (e.g. MOFs) due to their unique coordination ability and selectivity for cesium ions. These adsorbents combined the advantages of extraction and adsorption methods and showed high adsorption capacity for cesium ions, which are promising for cesium separation The key restraints for cesium separation, as well as the newest progress of the adsorbents for cesium separation were also discussed. Finally, some concluding remarks and suggestions for future researches were proposed.

• Journal of the Korean Electrochemical Society
• /
• v.15 no.4
• /
• pp.256-263
• /
• 2012

This study was performed to investigate the separation of cesium cations by using an electrochemical ion exchanger of nickel hexacyanoferrate($KNiFe(CN)_6$) film electrode. Potential, current, and charge passing through the cyclic voltammograms were measured in singular and binary solutions of 1.0M $NaNO_3$ and 1.0M $CsNO_3$. Before and after each experiment, the structural morphology and atomic composition of $KNiFe(CN)_6$ were analyzed by SEM and EDS, respectively. The ion selectivity of $KNiFe(CN)_6$ was also observed by the voltammograms and atomic compositions measured in the solution alternated between sodium and cesium. As the result of this study, it was found that the electrically switched $KNiFe(CN)_6$ ion exchanger had the significant advantage of 40 times or longer durability than conventional organic or inorganic ion exchanger. It was also shown that the $KNiFe(CN)_6$ ion exchanger had high selectivity for cesium over sodium.

• Journal of the Korean Chemical Society
• /
• v.46 no.6
• /
• pp.515-522
• /
• 2002

Solid beta-dicalcium silicate hydrate $(\beta-C_2SH)$ synthesized under hydrothermal conditions at $240^{\circ}C$ and Ca/Si=2 molar ratio shows cation exchange properties towards divalent metal cations such as Fe, Cu, Zn, Cd, or Pb. The ability of metal cation uptake by the solid was found to be in the order: $Fe^{2+}$〉$Cu^{2+}$〉$Zn^{2+}$〉$Cd^{2+}$ = $Pb^{2+}$. Cesium selectivity of the solid was demonstrated in the presence of univalent cation such as $Li^+$, $Na^+$ and $K^+$ and divalent cations such as $Ca^{2+}$, $Mg^{2+}$ and $Ba^{2+}$, which are one hundred times more concentrated than the $Cs^+$. The uptake of $Cs^+$ is maximum in the presence of $Mg^{2+}$ whereas it is minimum in the presence of $K^+$. The different affinities of ${\beta}-C_2SH$ towards divalent metal cations can be used for the separation of those ions. Due to its selectivity for cesium it can be used in partitioning of radioactive Cs+ from nuclear wastes containing numerous cations. The mechanism of the metal cation exchange and cesium selectivity reactions by the solid is studied.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.7
• /
• pp.957-958
• /
• 2004

• Bulletin of the Korean Chemical Society
• /
• v.18 no.9
• /
• pp.1014-1017
• /
• 1997

1,3-Dipropyloxycalix[4]arene dibenzocrown ethers were synthesized in the fixed 1,3-alternate conformation by the reaction of 1,3-dipropyloxycalix[4]arenes with a dibenzo dimesylates. Complexation toward alkali metal ions using ISEs showed a high cesium selectivity. Conformational flexibility of the corresponding 1,3-alternate calixcrown ether (4) with respect to the NMR time scale is found to depend on the temperature and polarity of the NMR solvent.

• Journal of the Korean Chemical Society
• /
• v.27 no.2
• /
• pp.127-132
• /
• 1983

The catalytic activity of ZSM-5 catalyst for the disproportionation of toluene is dependent on the type of cation exchanged, the degree of ion-exchange and the reaction temperature. The activity increases in the order of alkaline-, alkali earth-, hydrogen, and rare-earth-exchanged ZSM-5 and decreases with increasing degree of cation exchange. Among the ion-exchanged ZSM-5 catalyst, only Cs-ZSM-5 shows predominant selectivity for p-xylene. The selectivity increases with increasing degree of $Cs^+$-exchange and decreasing reaction temperature. This phenomenon is interpreted in terms of shape selectivity arising from the partial blocking of channel intersections by large cesium ions.

• Journal of the Korean Chemical Society
• /
• v.28 no.1
• /
• pp.62-69
• /
• 1984

The reaction of toluene with ethanol was studied over various cation-exchanged pentasil zeolite catalysts. The toluene disproportionation reaction to produce xylenes increased with increasing reaction temperature and the activity of alkylation of toluene with ethanol showed maximum at around $400^{\circ}C$. Only Cs-ZSM-5 catalyst showed pronounced p-ethyltoluene selectivity increasing to 96% with increasing degree of Cs-exchange. The sorption rate of m-xylene was lower for Cs-exchanged ZSM-5 than H-ZSM-5 catalyst. These phenomena were interpreted in terms of shape selectivity arising from the partial blocking of channel intersections by large cesium ions.

• Macromolecular Research
• /
• v.13 no.2
• /
• pp.141-146
• /
• 2005

Calix[4]crown-6-2,4-bis(4-aminobutyl ether), which has a crown-6 moiety at the 1,3-position and amino function at the 2,4-position, was prepared as an intermediate for the subsequent synthesis of calix[4]crown-6-containing polyamide and polyimide using adipoyl chloride and 1,2,4,5-benzenetetracarboxylic dianhydride. The chemical structures were characterized by IR, $^{1}H NMR$ spectroscopy and elemental analysis, and some of their physical properties, including their thermal behavior, were examined. The ion binding characteristics of the monomer and polymers for alkali metal and alkali earth metal ions were measured by liquid-liquid extraction from the aqueous phase into the organic phase. It has been observed that polyamide has a high binding ability towards various metal cations as compared to polyimide, which showed cesium ion selectivity.