K-Na exchange equilibria between muscovite-paragonite solid solution and hydrothermal chloride solutions

1985 ◽  
Vol 49 (353) ◽  
pp. 515-521 ◽  
Author(s):  
M. L. Pascal ◽  
J. Roux
Keyword(s):  
Solid Solution ◽  
Free Energy ◽  
Ion Exchange ◽  
Aqueous Solutions ◽  
Dissociation Constants ◽  
Excess Free Energy ◽  
Exchange Equilibrium ◽  
Chloride Solutions ◽  
Ion Exchange Reaction ◽  
The Difference

AbstractThree ion exchange equilibrium isotherms between muscovite-paragonite solid solution and 2-molal KCl-NaCl aqueous solutions have been studied at (1) 420°C 1 kbar, (2) 420°C, 2 kbar, and (3) 550°C, 2 kbar. The ΔG°(Joules) ± 2σ of the ion exchange reaction are: ΔG° (1) = −17 259±686, ΔG° (2) = −18 268 ± 560, ΔG° (3) = −16018 ± 336. The excess mixing parameters (‘subregular solution’) of the solid solution (at 1 bar) have been calculated:The corresponding binodal compositions are (muscovite mol fraction): 12–56% at 420 °C, 1 bar and 15–51% at 550 °C 1 bar. The compositions of micas in equilibrium with perthites (high structural state) at 400, 500, 600 °C and 2 kbar are respectively: Xmus = 91, 86, and 82%.The mixing properties of the solution were estimated using the speciation of two molal chloride solutions calculated from the dissociation constants of NaCl and KCl in aqueous solution. Although NaCl appears to be substantially more dissociated than KCl, the resulting excess free energy of mixing of the hydrothermal (Na,K)Cl solution was found less than 500 J at temperatures above 400 °C and pressures up to 2 kbar.The difference in Gibbs free energy of formation (from the elements at 25 °C, 1 bar) between NaCl and KCl in two molal aqueous solutions is proposed:

Surfaces, Interfaces, and Changing Shapes in Multilayered Films

MRS Bulletin ◽  
1999 ◽  
Vol 24 (2) ◽  
pp. 39-43 ◽  
Author(s):  
Daniel Josell ◽  
Frans Spaepen
Keyword(s):  
Free Energy ◽  
Excess Free Energy ◽  
External Pressure ◽  
Electronic Density ◽  
Spherical Drop ◽  
Crystal Anisotropy ◽  
Fundamental Quantity ◽  
The Difference ◽  
Image Position ◽  
Work Done

It is generally recognized that the capillary forces associated with internal and external interfaces affect both the shapes of liquid-vapor surfaces and wetting of a solid by a liquid. It is less commonly understood that the same phenomenology often applies equally well to solid-solid or solid-vapor interfaces.The fundamental quantity governing capillary phenomena is the excess free energy associated with a unit area of interface. The microscopic origin of this excess free energy is often intuitively simple to understand: the atoms at a free surface have “missing bonds”; a grain boundary contains “holes” and hence does not have the optimal electronic density; an incoherent interface contains dislocations that cost strain energy; and the ordering of a liquid near a solid-liquid interface causes a lowering of the entropy and hence an increase in the free energy. In what follows we shall show how this fundamental quantity determines the shape of increasingly complex bodies: spheres, wires, thin films, and multilayers composed of liquids or solids. Crystal anisotropy is not considered here; all interfaces and surfaces are assumed isotropic.Consideration of the equilibrium of a spherical drop of radius R with surface free energy γ shows that pressure inside the droplet is higher than outside. The difference is given by the well-known Laplace equation:This result can be obtained by equating work done against internal and external pressure during an infinitesimal change of radius with the work of creating a new surface.

Mixing entropy and the nucleation of silicides: Ni–Pd–Si and Co–Mn–Si ternary systems

2003 ◽  
Vol 18 (7) ◽  
pp. 1668-1678 ◽  
Author(s):  
C. Detavernier ◽  
X. P. Qu ◽  
R. L. Van Meirhaeghe ◽  
B. Z. Li ◽  
K. Maex
Keyword(s):  
Solid Solution ◽  
Free Energy ◽  
Gibbs Free Energy ◽  
Ternary Systems ◽  
Nucleation Temperature ◽  
Alloying Element ◽  
Entropy Of Mixing ◽  
Mixing Entropy ◽  
Nucleation Barrier ◽  
The Difference

Nucleation can play an important role during the formation of silicides, especially when the difference in Gibbs free energy ΔG between the existing and newly formed phase is small. In this work, it is shown that the addition of elements that form a solid solution with either the existing or nucleating phase influences the entropy of mixing and thus changes ΔG. In this way, the height of the nucleation barrier may be controlled, thus controlling the nucleation temperature. The influence of mixing entropy on silicide nucleation is illustrated by experiments for two ternary systems: Co–Mn–Si and Ni–Pd–Si. It is shown that the nucleation temperature of CoSi2 is increased by the addition of Mn, the nucleation temperature of MnSi1.7 is increased by the presence of Co, the nucleation temperature of NiSi2 is increased by the addition of Pd, and the nucleation temperature of PdSi is decreased by the addition of Ni. In all four cases, the effect of the alloying element on the nucleation temperature can be explained by a model on the basis of the concept of mixing entropy.

scholarly journals Ion-Exchange Reaction Thermodynamics to Study the Selectivity Behaviour of Nuclear and Non-Nuclear Grade Anion Exchange Resins

2014 ◽  
Vol 25 ◽  
pp. 8-15
Author(s):  
P.U. Singare ◽  
A.N. Patange
Keyword(s):  
Ion Exchange ◽  
Anion Exchange ◽  
Ion Selectivity ◽  
Equilibrium Constants ◽  
Exchange Reactions ◽  
Ion Exchange Reaction ◽  
Anion Exchange Resins ◽  
Bromide Ion ◽  
The Difference ◽  
Exchange Resins

In the present investigation, attempts were made to understand the difference in bromide ion selectivity of the two closely related anion exchange resins Auchlite ARA-9366 and Auchlite A-378 in chloride form. The selectivity difference was predicted based on the thermodynamic equilibrium constants and enthalpy values of Clˉ/Brˉ ion exchange reactions performed by using the two resins. During Clˉ/Brˉ exchange reactions, with rise in temperature from 30.0°C to 45.0 °C, the equilibrium constant (K) values were observed to decreases from 8.15x10-2 to 6.06x10-2 for Auchlite ARA-9366 resins and from 2.16x10-2 to 1.10x10-2 for Auchlite A-378 resins. The decrease in K values with rise in temperature, indicate exothermic ion exchange reactions having enthalpy values of -36.14 and -18.38 kJ/mol respectively. The high K and low enthalpy values obtained for Auchlite ARA-9366 resins indicate their greater selectivity for the bromide ions in the solution as compared to Auchlite A-378 resins.

Phosphate removal from aqueous solutions using (vinylbenzyl)trimethylammonium chloride grafted onto polyester fibers

2015 ◽  
Vol 71 (12) ◽  
pp. 1875-1883 ◽  
Author(s):  
HyunJu Park ◽  
Duc Canh Nguyen ◽  
Choo-Ki Na
Keyword(s):  
Free Energy ◽  
Ion Exchange ◽  
Aqueous Solutions ◽  
Sorption Capacity ◽  
Phosphate Removal ◽  
Trimethylammonium Chloride ◽  
Order Kinetic ◽  
Phosphate Sorption ◽  
Maximum Sorption Capacity ◽  
Competing Anions

In this study, we investigated the removal of phosphate from aqueous solutions using (vinylbenzyl)-trimethylammonium chloride (VBTAC) grafted onto poly(ethylene terephthalate) (PET) fibers (PET-g-VBTAC). Batch-mode experiments were conducted using various contact times, initial phosphate concentrations, temperatures, pH values, and competing anions, to understand phosphate sorption onto PET-g-VBTAC. The phosphate sorption capacity of PET-g-VBTAC increased with increasing solution pH and was highest near pH 7. The equilibrium data fitted the Langmuir isotherm model well. The maximum sorption capacity (qm) of PET-g-VBTAC for phosphate was 55.6–56.0 mg/g at 25–45 °C. The sorption process followed a pseudo-second-order kinetic model. The obtained values of the mean free energy indicated that sorption of phosphate on PET-g-VBTAC occurs via ion exchange. Thermodynamic parameters, enthalpy change, entropy change, and Gibb's free energy, confirmed that phosphate sorption was spontaneous and endothermic. The adverse effects of competing anions on phosphate removal by PET-g-VBTAC were insignificant. These results demonstrate that PET-g-VBTAC effectively removes phosphate from aqueous solutions by ion exchange.

scholarly journals Comparative Study of Uni-Univalent H+/Na+ and Uni-Bivalent H+/Ca2+ Ion Exchange Reactions Using Nuclear Grade Resin Indion-223

2014 ◽  
Vol 33 ◽  
pp. 127-135
Author(s):  
Pravin U. Singare ◽  
Akmal L. Khan Mohammed ◽  
N.N. Dixit
Keyword(s):  
Ion Exchange ◽  
Exchange Reaction ◽  
Exchange Resin ◽  
Anion Exchange Resin ◽  
Equilibrium Constants ◽  
Nuclear Grade ◽  
Exchange Equilibrium ◽  
Exchange Reactions ◽  
Equilibrium Studies ◽  
Ion Exchange Reaction

The present paper deals with the ion exchange equilibrium studies of uni-univalent and uni-bivalent ion exchange reactions using nuclear grade anion exchange resin Indion-223 in H+ form towards Na+ and Ca2+ ions in the solution. It was observed that with rise in temperature the equilibrium constants K values for H+/Na+ uni-univalet ion exchange reaction increases from 0.01389 to 0.01855. Similarly for H+/Ca2+ uni-bivalet ion exchange reaction the equilibrium constants K values increases from 0.000397 to 0.000639. The increase in equilibrium constant values with rise in temperature indicate endothermic ion exchange reactions having the enthalpy change values of 25.55 and 38.92 kJ/ mol respectively.

Preparation and thermoresponsive properties of helical polypeptides bearing pyridinium salts

RSC Advances ◽  
2015 ◽  
Vol 5 (51) ◽  
pp. 40772-40778 ◽  
Author(s):  
Yan Wu ◽  
Xi Wang ◽  
Ying Ling ◽  
Haoyu Tang
Keyword(s):  
Ion Exchange ◽  
Aqueous Solutions ◽  
Exchange Reaction ◽  
Solution Temperature ◽  
Pyridinium Salts ◽  
Critical Solution Temperature ◽  
Ion Exchange Reaction ◽  
Upper Critical Solution Temperature

Polypeptides bearing 3-methylpyridinium groups and BF4− prepared by nuleophilic substitution and ion-exchange reaction showed upper critical solution temperature (UCST)-type transitions in aqueous solutions.

scholarly journals Ion Exchange Equilibrium Studies of Uni-Univalent H+/Na+ and Uni-Bivalent H+/Mg2+ Ion Exchange Reactions Using Nuclear Grade Resin Indion-223

2014 ◽  
Vol 33 ◽  
pp. 199-207
Author(s):  
Pravin U. Singare ◽  
Akmal L. Khan Mohammed ◽  
N.N. Dixit
Keyword(s):  
Ion Exchange ◽  
Exchange Reaction ◽  
Equilibrium Constants ◽  
Ionic Species ◽  
Nuclear Grade ◽  
Exchange Equilibrium ◽  
Exchange Reactions ◽  
Equilibrium Studies ◽  
Ion Exchange Reaction ◽  
Selection Of

In the present investigation the uni-univalent and uni-bivalent ion exchange reactions were studied using nuclear grade anion exchange resin Indion-223 in H+ form. It was observed that for H+/Na+ uni-univalet ion exchange reaction, with rise in temperature the equilibrium constants K values increases from 0.01389 to 0.01855. Similarly increase in K values was observed from 0.000177 to 0.000333 for H+/Mg2+ uni-bivalet ion exchange reaction. The increase in equilibrium constant values with rise in temperature indicate endothermic ion exchange reactions having the enthalpy change values of 25.55 and 51.46 kJ/ mol respectively. It is expected that the present study will provide valuable information in order to decide about the selection of those resins for efficient separation of various ionic species present in the industrial waste water effluents.

Thermodynamics of Ion-Exchange Between Na+/Sr2+ Solutions and the Zeolite Mineral Cinoptilolite

1993 ◽  
Vol 333 ◽  
Author(s):  
Roberto T. Pabalan ◽  
F. Paul Bertetti
Keyword(s):  
Ion Exchange ◽  
Exchange Reaction ◽  
Activity Coefficients ◽  
Thermodynamic Model ◽  
Solution Concentration ◽  
Exchange Equilibrium ◽  
Ion Exchange Reaction ◽  
Aqueous Ions ◽  
Interaction Approach ◽  
Ion Exchange Isotherm

ABSTRACTIon-exchange experiments were conducted at 25 °C between the zeolite mineral clinoptilolite and aqueous solutions of varying equivalent ratios of Na+ and Sr2+ and total concentrations of 0.005, 0.05, and 0.5 N. The experiments were designed to investigate the effects of changes in total solution concentration and in the relative concentrations of exchangeable cations on the following ion-exchange equilibrium:Sr2+ + 2NaZ ⇄ SrZ2 + 2Na+Using the isotherm data at 0.05 N solution concentration, a thermodynamic model for the ion-exchange reaction was derived using a Margules formulation for the activity coefficients of zeolite components and the Pitzer ion-interaction approach for activity coefficients of aqueous ions. The results of the forward experiments showed that the ion-exchange isotherm strongly depends on the total solution concentration. Additional experiments demonstrated that the above ion-exchange reaction is reversible. The derived equilibrium constant, K, and Gibbs energy of ion-exchange, ΔG°, are equal to 0.321±0.021 and 2,820±170 J/mol, respectively.Using thermodynamic parameters derived from the 0.05 N isotherm experiment, the model was used to predict isotherm values at 0.005 and 0.5 N, which showed excellent agreement with measured data. Because the thermodynamic model used in this study can be easily extended to ternary and more complicated mixtures, it may be useful for modeling ion-exchange equilibria in multicomponent geochemical systems.

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