“…The corresponding calculated pH in our conditions is 8.9, experimentally we measured 8.6. In a previous work on cobalt exchange, we described how depending on time and the hydrolysis degree the cobalt species migrated and occupied different sites. , 9 Cesium retained in zeolites after leaching step, (a) zeolites A and (b) zeolites X.…”
Sodium zeolite X and sodium zeolite A have been exchanged with cesium solutions prepared from three
cesium salts (chloride, nitrate, and acetate). Depending on the solution, the cesium cations were found to be
located in different sites of the zeolite networks. If cesium acetate solution is used, then cesium reaches sites
SII and SIII in the large cavity whereas if nitrate or chloride solutions are put in contact with zeolites, cesium
is positioned only in sites SIII. This distribution determines the leaching behavior of the studied zeolites.
When the samples were thermally treated to encapsulate partially the cesium cations, it was found that their
behavior was different from the one observed in a previous work on cobalt exchanged X and A zeolites
“…The corresponding calculated pH in our conditions is 8.9, experimentally we measured 8.6. In a previous work on cobalt exchange, we described how depending on time and the hydrolysis degree the cobalt species migrated and occupied different sites. , 9 Cesium retained in zeolites after leaching step, (a) zeolites A and (b) zeolites X.…”
Sodium zeolite X and sodium zeolite A have been exchanged with cesium solutions prepared from three
cesium salts (chloride, nitrate, and acetate). Depending on the solution, the cesium cations were found to be
located in different sites of the zeolite networks. If cesium acetate solution is used, then cesium reaches sites
SII and SIII in the large cavity whereas if nitrate or chloride solutions are put in contact with zeolites, cesium
is positioned only in sites SIII. This distribution determines the leaching behavior of the studied zeolites.
When the samples were thermally treated to encapsulate partially the cesium cations, it was found that their
behavior was different from the one observed in a previous work on cobalt exchanged X and A zeolites
“…Because of its wide application in the field of nuclear medicine, its radioactive half *Author for correspondence (E-mail: blai2000@hotmail.com). life of 5.3 years and its gamma energy, it is important to retain and to separate from water [9,10]. The aim of this work was to study the 60 Co 2+ sorption from aqueous solution by hydrous manganese oxide powder.…”
Adsorption / Hydrous manganese oxide / 60 Co 2+ / Freundlich adsorption / Radioactive waste / Desorption Summary. Hydrous manganese oxide (HMO) was synthesized and its ability to sorb 60 Co 2+ from aqueous solution was studied under static conditions as a function of contact time, cobalt concentration (10 −2 -10 −7 M), temperature (303-333 K) and pH of adsorptive solution (2.2-11.4). X-ray diffraction was used in characterization of synthesized HMO. Low concentration of 60 Co 2+ solution, high pH and high temperature were the most favorable conditions for the adsorption process. The results show that the removal process is complete in 40 minutes, obeys a first order rate law and can be described using the Freundlich adsorption model. The standard enthalpy of the system was ∆H 0 = 12.5 ± 0.2 kJ mol −1 and cobalt desorption indicates that the uptake process proceeds via cation exchange. The removal of cobalt ions by HMO appears to be endothermic and irreversible. The values of calculated ∆G 0 and ∆S 0 were − 17.0 ± 3.0 kJ mol −1 and (9.8 ± 0.2) × 10 −2 kJ K −1 mol −1 respectively, this indicates spontaneity of the process and the degree of freedom of ions is increased by adsorption.
“…Suspensions of clay particles are the subject of numerous experimental and theoretical studies because of their use in many industrial applications (nuclear waste management, , drilling, heterogeneous catalysis). Their physicochemical properties (large adsorbing power, ionic exchange capacity, mechanical stability, acidity) − result from the strong electrostatic couplings between the clay surfaces and their ionic, polar, or polarizable intercalates.…”
Section: Introductionmentioning
confidence: 99%
“…Their physicochemical properties (large adsorbing power, ionic exchange capacity, mechanical stability, acidity) − result from the strong electrostatic couplings between the clay surfaces and their ionic, polar, or polarizable intercalates. Moreover, the understanding of the stability of clay materials at a fundamental level is crucial for various applications, such as the drilling of shales or the storing of ionic nuclear waste inside the interlamellar space of clays. , …”
(N,V,T) Monte Carlo simulations are performed by using hyperspherical geometry in order to investigate
the mechanical stability and the ionic affinity of clay particles neutralized by a mixture of counterions of
different valency. In this study, clay particles are described as uniformly charged surfaces and the
interactions between ions and these charged surfaces are described within the context of the ‘primitive
model'. The purpose of this study is to derive the maximum amount of monovalent counterions necessary
to remove the stability of clay materials neutralized by divalent or trivalent counterions. From the equation
of state of these charged materials we quantify the influence of ionic exchange on the interfacial free
energy.
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