Surface phase transformations, surface complexation and solubilities of hydroxyapatite in the absence/presence of Cd(II) and EDTA

2012 ◽  
Vol 27 (1) ◽  
pp. 15-21 ◽  
Author(s):  
Karin Viipsi ◽  
Staffan Sjöberg ◽  
Andrey Shchukarev ◽  
Kaia Tõnsuaadu
Keyword(s):  
Phase Transformations ◽  
Surface Complexation ◽  
Surface Phase

Comparison of a Non Electrostatic Surface Complexation Model and Surface Phase Theories for Prediction of Future Sorption Properties.

2004 ◽  
Vol 824 ◽  
Author(s):  
Allan T. Emrén ◽  
Anna-Maria Jacobsson
Keyword(s):  
Aqueous Solution ◽  
Chemical Potential ◽  
Surface Complexation ◽  
Sorption Properties ◽  
Phase Method ◽  
Detailed Knowledge ◽  
Surface Phase ◽  
Surface Complexation Model ◽  
Advantages And Disadvantages ◽  
The One

AbstractIn performance assessments, sorption of radionuclides dissolved in groundwater is mostly handled by the use of fixed Kd values. It has been well known that this approach is unsatisfying. Only during the last few years, however, tools have become available that make it possible to predict the actual Kd value in an aqueous solution that differs from the one in which the sorption properties were measured.One such approach is surface complexation (SC) that gives a detailed knowledge of the sorption properties. In SC, one tries to find what kinds of sorbed species are available on the surface and the thermodynamics for their formation from species in the bulk aqueous solution. Recently, a different approach, surface phase method (SP), has been developed. In SP, a thin layer including the surface is treated as a separate phase. In the bulk aqueous solution, the surface phase is treated as a virtual component, and from the chemical potential of this component, the sorption properties can be found.In the paper, we compare advantages and disadvantages of the two kinds of models. We also investigate the differences in predicted sorption properties of a number of radionuclides (Co, Np, Th and U). Furthermore, we discuss under which circumstances, one approach or the other is preferable.

scholarly journals Modelling of cutting induced surface phase transformations considering friction effects

2011 ◽  
Vol 19 ◽  
pp. 331-336 ◽  
Author(s):  
V. Schulze ◽  
J. Michna ◽  
J. Schneider ◽  
P. Gumbsch
Keyword(s):  
Phase Transformations ◽  
Surface Phase

An Approach to Sorption on Minerals Making Use of Surface Phase Thermodynamics

2003 ◽  
Vol 807 ◽  
Author(s):  
Allan T. Emrén
Keyword(s):  
Series Expansion ◽  
Aqueous Phase ◽  
Chemical Potential ◽  
Solid Phase ◽  
Surface Complexation ◽  
Performance Assessments ◽  
Surface Phase ◽  
Free Enthalpy ◽  
End Members ◽  
Model Curve

ABSTRACTIn performance assessments for nuclear wastes repositories, Kd values are often used to describe sorption of radionuclides on fracture surfaces. The weakness of the Kd concept is that values determined under certain conditions can only be used when the chemistry is similar to those. Alternatives include surface complexation models. The problem with such models is that the parameters required are not easily determined, and thus are missing for several systems.Another alternative is to use surface phase thermodynamics. Such a theory has been developed, in which the surface of a solid phase and the species adsorbed upon it are treated as a separate phase of variable composition. The composition is described in terms of pure end members. For each end member, the free enthalpy is described by a series expansion. To calculate coefficients, the theory makes use of the fact that at equilibrium, the chemical potential of a component has the same value in all phases. Thus, speciation of the bulk aqueous phase can be used. Making use of only the linear term in the expansion, one measured Kd value is enough to determine the corresponding coefficient.The theory has been applied to sorption of U(VI) on alumina with the aid of data from the literature. The coefficient was determined from the measured Kd values in the interval pH = 4 – 12. The resulting model curve was found to agree reasonably well with observed values, although the Kd varies by a factor of 200.

Grafting of alumina by diphenylphosphinate coupling agents

2000 ◽  
Vol 628 ◽  
Author(s):  
Gilles Guerrero ◽  
Gérald Chaplais ◽  
P. Hubert Mutin ◽  
Jean Le Bideau ◽  
Dominique Leclercq ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Solid State ◽  
Nmr Spectroscopy ◽  
Crystalline Phase ◽  
Surface Complexation ◽  
Organic Medium ◽  
Coupling Agents ◽  
Surface Phase ◽  
Alumina Particles ◽  
Surface Phase Transformation

ABSTRACTAlumina particles were treated under various conditions with different diphenylphosphinate compounds: diphenylphosphinic acid, ethyl diphenylphosphinate, and trimethylsilyl diphenylphosphinate. The balance between surface complexation (namely grafting) and surface phase transformation (formation of bulk aluminum phosphinate phase) was investigated by IR and solid-state 31P MAS NMR spectroscopy, using the model crystalline phase Al(O2PPh2)3 synthesized in a parallel work as a reference. Satisfactory grafting was obtained either by using diphenylphosphinic acid in aqueous medium at pH about 6, or by using ethyl diphenylphosphinate in organic medium as coupling agents.

scholarly journals Surface degradation of Li1–xNi0.80Co0.15Al0.05O2 cathodes: Correlating charge transfer impedance with surface phase transformations

2016 ◽  
Vol 108 (26) ◽  
pp. 263902 ◽  
Author(s):  
S. Sallis ◽  
N. Pereira ◽  
P. Mukherjee ◽  
N. F. Quackenbush ◽  
N. Faenza ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Phase Transformations ◽  
Surface Phase ◽  
Surface Degradation ◽  
Transfer Impedance

Dynamics of the surface phase transformations in the system

1996 ◽  
Vol 363 (1-3) ◽  
pp. 289-295 ◽  
Author(s):  
Z.C. Ying ◽  
J. Wang ◽  
E.W. Plummer
Keyword(s):  
Phase Transformations ◽  
Surface Phase

Oxygen adsorption on palladium(100) surface: phase transformations and surface reconstruction

1991 ◽  
Vol 95 (11) ◽  
pp. 4522-4528 ◽  
Author(s):  
Gary W. Simmons ◽  
Yarw Nan Wang ◽  
Juan Marcos ◽  
Kamil Klier
Keyword(s):  
Phase Transformations ◽  
Surface Reconstruction ◽  
Oxygen Adsorption ◽  
Surface Phase
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