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  • Author or Editor: E. Chmielewská-Horváthová x
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Abstract  

137Cs and134Ba were removed from synthetic aqueous solutions by means of natural zeolites of Slovakian origin. The equilibrium sorption behavior of Cs and Ba ions onto clinoptilolite and mordenite were studied under static as well as dynamic experimental conditions. Both Freundlich and Langmuir isotherms describe satisfactory by Cs and Ba adsorption on the zeolites studied. The elution of Cs and Ba ions from zeolite columns after the loading cycle was undertaken additionaly, in order to compare column operating runs of various exchanged zeolite forms.

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Abstract  

The possibility to use the monoionic Ag+-form (eventually Hg+- and Hg2+- forms) of clinoptilolite of domestic origin for radioactive iodide elimination from waters has been studied. The capacity of the monoforms of clinoptilolite towards iodide exceeds many times that of the capacity of clinoptilolite in natural form. Due to the low solubility product of AgI, Hg2I2 and HgI2 iodides generate precipitates on the zeolite surface. Rtg analyses of the silver form of clinoptilolite after sorption of iodide demonstrate the formation of new crystals on the zeolite surface. The influence of interfering anions on the adsorption capacity of silver clinoptilolite towards iodide was investigated, too. Kinetic curves of iodide desorption from the surface of silver and mercury clinoptilolite were compared. Simultaneously, adsorption isotherms for the systems aqueous iodide solution/Ag, Hg-clinoptilolite were determined.

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Abstract  

The subject of this paper was to study Co2+-ion removal from aqueous solutions by means of natural mordenite and clinoptilolite. The mentioned zeolites were of Slovak origin (SFR). The static and dynamic equilibrium adsorption of Co2+-ions by zeolites, the influence of pH, quality and quantity of interfering ions on adsorbate/adsorbent system were investigated. The influence of flow rate, activation and initial concentration on the shape of the breakthrough curve was examined in dynamic regime. Mathematical expression was found for the breakthrough curve description.

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Abstract  

Uptake of iodide radionuclide from model solutions has been tested by means of three various deposit clinoptilolites (of Niný Hrabovec — Slovakia, Mád — Hungary and Wyoming —USA). The samples were chemically modified into more or less Ag-forms and the tests on adsorption were performed using columns packed with grain-sized zeolites. Breakthrough properties of iodide in dependence of competive chloride and phosphate ions were examined, respectively. Mathematical expressions of the adsorption profiles of iodide in Ag-columns as well as some Shilov constants of dynamic experiments were estimated. The highest capacity data to iodide were exhibited by the Ag-modified Slovakian clinoptilolite (102.7 mg/g) and the lowest one by the Hungarian sample (71.6 mg/g).

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Abstract  

The aim of this study was to evaluate the quantitative and qualitative influence of some ions (ammonium, cesium, barium) on the adsorption capabilities of natural and chemically modified clinoptilolite towards Cs and Ba ions. Na–Cs–Ba — ternary ion-exchange isotherms at 23 °C were measured and plotted in a triangular diagram. Using statistical methods, linearized forms of isotherms (Freundlich, Langmuir, BET) for the systems studied are given.

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