Application of the Electrical Double Layer Theory to Predict Ion Adsorption in Mixed Ionic Systems

Ravina, Israela; Gur, Y.

doi:10.1097/00010694-197804000-00003

Cited by 8 publications

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“…Their analysis was limited, however, to the special case where interaction between adjacent platelets is negligible, i.e., where Yd is practically zero or cosh Y d ( = v d) essentially one. A revised approach incorporating Stern-layer (near-surface) modifications has been tested by Ravina and Gur (1978). This effect can be readily evaluated from Eq.…”

Section: Diffuse Double Layer Approachmentioning

confidence: 99%

Saline and Sodic Soils

Bresler

McNeal

Carter

1982

Advanced Series in Agricultural Sciences

390

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Section: Diffuse Double Layer Approachmentioning

confidence: 99%

Saline and Sodic Soils

Bresler

McNeal

Carter

1982

Advanced Series in Agricultural Sciences

390

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“…In close proximity to the surface, the anion concentration C a → 0, the cation concentration C c → ∞, the potential ψ → −∞, and the negatively charged surface of a clay flake, together with the adsorbed cation charges, form an electrical double layer [3][4][5][6][7][8].…”

Section: Elements Of Electrical Double Layer Theory Static Potentialmentioning

confidence: 99%

“…The electric field potential should satisfy the Poisson-Boltzmann equation [8] div (ε grad ψ) = −4πq,…”

Section: Elements Of Electrical Double Layer Theory Static Potentialmentioning

confidence: 99%

“…Introducing the independent variable x = 2AC b c y, we write expression (8) in the form Figure 3 gives the distribution of the weighed potential in the pore space between parallel planes at α = 0.8 (on the ordinate is the variable ξ = x b − x). In this case, the dimensionless distances from the particle surface to the middle plane of the pore x b = 3.80, 3.85, and 4.40 correspond to the values u s = 2, 4, and 6.…”

Section: Generally Eq (8) Is Solved Numericallymentioning

confidence: 99%

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Equilibrium self-polarization of clay

Корсакова

Пеньковский

2007

J Appl Mech Tech Phys

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UDC 532.546:550.820.7 N. K. Korsakova and V. I. Pen'kovskiiA condition of equilibrium between charged clay particle surfaces and the solution contained in the pore space of the rock is derived using electrical double layer theory. This condition is the relation linking the cation concentration in the middle surface of the pores with the exchange capacity of the clay, the total ion charges, and the specific surface area of the particles.Introduction. The occurrence of a self-polarization potential in clay-containing rocks is often associated with diffusion and adsorption (membrane) effects [1, 2], which are described by Nernst theory for semipermeable membranes. By the membrane is meant a certain boundary between solutions with different salt concentrations.There is also another approach based on the theory of the electrical double layer [3-5] formed on the surface of charged clay particles. Some aspects of using this theory were studied, for example, in [6-9] and other papers.Clays of various types, constituting half of all sedimentary rocks of the Earth's crust, have special properties that distinguish them from the other minerals. The clay-mineral skeleton is formed of thin (about a few tens of angstroms) flakes. Clays, while exhibiting fairly high porosity, are poorly permeable to native fluids [10]. Their crystal lattice contains molecules of Al 2 [Si 4 O 10 (OH) 2 ]nH 2 O. Instead of aluminum the molecules can contain iron atoms or, much more rarely, other metal atoms.Because clay molecules contain a large amount of oxygen atoms, the flake surface has a stationary negative charge related to the crystal lattice. In the presence of fresh water, the flakes are hydrated similarly to salt ions in electrolytes, leading to a volume increase (swelling) of the clay. Conversely, if the pore space of a clay mineral is filled with a solution of salts, some of the water molecules adsorbed on the flake surface can pass into the solution, thus diluting it, and the active centers (vacancies) that have become free are occupied by cations from the pore solution. An excessive number of negative charges (anions) appear in the solution. This phenomenon was called anion displacement or negative adsorption [6].Thus, the displacement of fresh water from a clay bed by a salt solution gives rise to a negative potential difference in the penetration region. With time, the excessive negative charge "drains" into the ambient rocks under the action of the generated electric field and diffusion until general equilibrium is established, i.e., until the electric potentials of the bed are equalized.Obviously, the equilibrium is also disturbed if re fresh water is injected in a clay bed saturated with an electrolyte solution. As a result, the initially neutral infiltrate is saturated with the cations desorbed from the clay particle surface, and the vacancies are filled by dipole water molecules. A potential with a positive sign occurs in the penetration region.In the construction of a mathematical model for the formation and decay of the self...

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“…όπου C, (x,t) είναι η συγκέντρωση της υγρής φάσης* (M cm" 3 ), 5, (x,t) είναι η συγκέντρωση της στερεάς φάσης (M g" 1 ), ρ η πυκνότητα όγκου του πορώδους υλικού (g cm" 4. ΜΟΝΤΕΛΑ ΑΝΤΑΛΛΑΓΗΣ ΙΟΝΤΩΝ ιόντων (cm h" 1), D ο συντελεστής διασποράς (cm 2 h" 1 ) και χ, t είναι η απόσταση (cm) και ο χρόνος (h) (Murali et aU 1981, Persaud et al, 1982Grant et al, 1995 (Shainberg and Kemper, 1967;Ravina and Gur, 1978;Nir, 1986;Bolt, 1987).…”

Section: μοντέλα προσρόφησης ιόντων σε πορώδη υλικάunclassified

Μελετη Της Δεσμευσης Ραδιενεργων Ρυπων Απο Υποστυλωμενα Φυλλομορφα Αργιλοπυριτικα Υλικα

Καραμανησ¹

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The aim of the research presented in this thesis was the study of the selective sorption of radioactive cesium and strontium in Pillared Layered Clays (PILCs). Two reference samples, coded ATFflNA and AZA, were initially used in experiments both in vitro and in vivo. An improved pillared clay, coded FRAZA, was constructed, characterised by several methods (XRD, XRF, PIGE, N 2 adsorption-desorption, radiotracers' exchange isotherms) and employed in exchange experiments. The reference samples and the material FRAZA differed in both the nm and μηι scales as a result of the different organisation and structural evolution of the clay layers. Furthermore, four different methods, defined as method A, Β etc, were tested for restoring the cation exchange capacity (CEC) of the thus prepared PILCs. The most effective proved method D which involved exposing the material to ammonia fumes followed by soaking in a sodium alkaline solution.Samples of ATHINA-A and AZA-A were used in the in vitro sorption experiments under static conditions. Kinetic experiments were analysed through the laws of isotopie exchange and film diffusion as the rate-determining step. Sorption rates of the order of hours were observed. The application of a phenomenological model developed for the interpretation of the results obtained in these experiments (NPL model), determined the selectivity coefficients of Cs or Sr over competitive cations of Na, Κ, Η and Ca. The observed PILCs' selectivity was interpreted through the electrostatic interaction of the cations and the negative charged clay layers. Furthermore, the influence of pH, solution volume and temperature in radiostrontium sorption was studied while, in experiments with cation concentrations simulating rumen liquid, the NPL model predicted the observed strontium sorption percentages. Comparison of PILCs with cyanoferrates (AFCF) revealed the reasons of AFCF effectiveness in cesium sorption and PILC superiority in strontium sorption. An unsuccessful in vivo experiment involving PILC administration to ruminants was attributed mainly to the limited time of contact between the material and strontium in the digestive tract of the animals and the insufficient material CEC restoration (method A).The materials AZA-D and FRAZA-D were used in cation exchange experiments. Cesium or strontium uptake was faster in FRAZA-D than AZA-D under both static and dynamic experimental conditions. This result was attributed to the different microscopic and macroscopic structure that materials possessed. Moreover, the separation factors Sr-Na and Sr-Ca were determined for FRAZA-D with values greater than 40 and 2 respectively. The selectivity of FRAZA-D for strontium sorption over several monovalent and divalent competitive cations was further confirmed in experiments with rumen liquid. The results derived from FRAZA-D administration in ruminants for strontium and cesium sorption were positive and promising for further investigation and research.

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Application of the Electrical Double Layer Theory to Predict Ion Adsorption in Mixed Ionic Systems

Cited by 8 publications

References 0 publications

Saline and Sodic Soils

Saline and Sodic Soils

Equilibrium self-polarization of clay

Μελετη Της Δεσμευσης Ραδιενεργων Ρυπων Απο Υποστυλωμενα Φυλλομορφα Αργιλοπυριτικα Υλικα

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