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Abstract  

The heats of immersion (in water) of outgassed clinoptilolite and its ion-exchanged forms were measured with a Calve calorimeter at 30°C, and the integral heats of sorption were calculated therefrom in order to use zeolites in heating and cooling applications. The immersion and sorption heats were studied as functions of the water saturation degree and the cation contents. The changes observed in the slopes of the sorption curves at low saturation for Ca2+ and Mg2+ ion-exchanged forms were related to the thermal destruction of the heulandite-type structure.

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Abstract  

The mechanism of surfactant adsorption on various forms of clinoptilolite was studied by DTA, TG and DTG analyses. The examined series of surfactant modified clinoptilolite (SMC) was previously prepared by the adsorption of the surface-active oleylamine on Ca2+, Na+, H+ and mechanochemically treated forms of clinoptilolite. The oleylamine was most strongly adsorbed on H+-forms of clinoptilolite due to the largest number and strength of adsorption sites. The surfactant adsorption mechanism on H+-form of clinoptilolite was studied by recording the series of variously surfactant-loaded samples. The products of sulphate, dihydrogenphosphate and hydrogenchromate adsorption on SMC were analyzed by DTA, TG and DTG in order to investigate the mechanism of anion adsorption.

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Abstract  

The adsorption kinetics of H2O in a clinoptilolite rich zeolitic tuff was experimentally investigated at 18°C. In the identification of the diffusion mechanism the isothermal adsorption model equation was used. It was found out that the intraparticle mass transfer becomes more dominant over the heat transfer with increase in particle size and the adsorptive dose pressure. Although initially intraparticle mass transfer was the controlling resistance later external heat transfer also contributes to the transfer mechanism.

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Abstract  

An iodine containing natural zeolitic material of the clinoptilolite type heated to different temperatures was investigated by means of X-ray photoelectron spectroscopy and thermal analysis methods. At room temperature the iodine was found to be present, depending on the preparation conditions, in the form of iodide or iodide combined with elementary iodine. After heating to 200°C, only iodide was observed which persists in the product in a small amount also after heating to 900°C.

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Abstract  

Samples of clinoptilolite were modified using insoluble hexacyanoferrate from aqueous solution. The modified samples were characterized by elemental analysis, powder X-ray diffraction, solid state NMR and vibrational spectroscopy. The sorption properties of modified clinoptilolite were studied, too. Higher affinity for137Cs sorption in comparison with the natural clinoptilolite has been proved.

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sieves and catalysts [ 13 – 15 ]. The natural zeolite of the clinoptilolite type is one of the world's most abundantly occurring and used zeolitic mineral. Clinoptilolite is a member of the heulandite group of natural zeolite. The unit cell is monoclinic

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Journal of Thermal Analysis and Calorimetry
Authors: D. Sternik, M. Majdan, A. Deryło-Marczewska, G. Żukociński, A. Gładysz-Płaska, V. M. Gun'ko, and S. V. Mikhalovsky

[ 8 – 11 ]. In this aspect, interaction of natural minerals with water and organics is of importance [ 11 – 13 ]. Bentonite and clinoptilolite are natural minerals composed of the aluminosilicate matrix with a variety of embedded other metal

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tribochemical treatment [ 1 , 2 ]. Natural clinoptilolite is a mineral of volcanic activity origin forming large industrial deposits. Added in the soil, this zeolite improves the soil structure and act favorably on the soil fertility due to its high ion

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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 sorption of cobalt on natural and modified clinoptiolites has been studied. It has been demonstrated that the higher sorption of cobalt on modified clinoptinolites than on natural ones is due to precipitation reactions. The precipitates formed on the sorbent have been investigated by infrared spectrometrical, microscopical, and X-ray analyses. The capacity values of the corresponding metal forms of clinoptilolite have been obtained with cobalt. Desactivation of radioactive solutions containing134Cs,137Cs204Tl and The sorption of cobalt on natural and modified clinoptiolites has been studied. It has been demonstrated that the higher sorption of cobalt on modified clinoptinolites than on natural ones is due to precipitation reactions. The precipitates formed on the sorbent have been investigated by infrared spectrometrical, microscopical, and X-ray analyses. The capacity values of the corresponding metal forms of clinoptilolite have been obtained with cobalt. Desactivation of radioactive solutions containing134Cs,137Cs,204Tl and60Co ions simultaneously on natural sorbents by precipitation reaction has been achieved.

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