Sorption equilibrium heterogeneity

Karapanagioti, H. K., S. Kleineidam, D. A. Sabatini, P. Grathwohl, and B. Ligouis, Impacts of heterogeneous organic matter on phenanthrene sorption Equilibrium and kinetic studies with aquifer material , Environ. Sci. Technol., 34, 406-414 (2000). 

FR measurements In order to avoid effects of bed formation and particle size heterogeneity samples of narrow CNT sieve fractions were distributed evenly over a glass-wool plug, placed in the sample holder of the batch-type FR system. A detailed description of the FR system is given in ref [22]. Samples were pre-treated in situ in high vaemun at 300 °C for 1 hour. Then, sorption equilibrium was established between the adsorbent and the sorptive alkane. The temperature and pressure of the FR measurements... 

There was studied dependence of sorption rate values of microamounts high listed elements from time of their contact with sorbents, pH media and means of equilibrium concentration. It is shown that owing to exchange of sorbents surface characteristics, its hydrating rate value and heterogeneity of sorbate and hydrolyzed forms of metals investigated interaction with surface can simultaneously proceed on several mechanisms. The contributions of various factors into adsorption of elements-analogues are depended from sorption conditions and nature of sorbent surface. 

Rabideau, A. J., and Miller, C. T. (1994). "Two-dimensional modeling of aquifer remediation influenced by sorption non-equilibrium and hydraulic conductivity heterogeneity." Water Resour. Res., 30(5), 1457-1470. 

Lipatov798 recognized that the sorption of Methylene Blue on starch is a heterogenous neutralization reaction of neutralization in which starch acts as an acid. Adsorption isotherms of Methylene Blue on starch indicate that it is an equilibrium process and that swelling as well as other internal structural factors are responsible for the sigmoidal shape of the isotherm.799-800 It is also known that the Langmuir isotherm is affected by equilibrium between the monomer and dimer forms of Methylene Blue, both of which are capable of adsorption on starch (Table XLV).801... 

Figure 13.29. Schematic sorption isotherms of a metal ion (Me) on an oxide (XO ) at constant pH (a) adsorption only (H) adsorption and surface precipitation via ideal solid solution (c) adsorption and heterogeneous nucleation in the absence of a free energy nucleation barrier (AG 0) adsorption and heterogeneous nucleation of a metastable precursor (e) same as in (3) but with transformation of the precursor into the stable phase. The arrows show the isotherm evolution for continual addition of dissolved Me. The initial isotherm with the slope of 1 (in the double logarithmic plot) corresponds to a Langmuir isotherm (surface complex formation equilibrium). [Me]s , = solubility concentration of Me for the stable metal oxide [Me]p = solubility concentration of Me for a metastable precursor (e.g., a hydrated Me oxide phase). (From Van Cappellen, 1991.)...

Biologically derived macromolecules are highly heterogeneous in site distribution from composition differences in monomers and where amorphous/crystalline regions are present. The differences previously found in sorption are related to the difference in equilibrium time for static and chromatographic methods ( 8). 

This work focused on the use of the DRM to characterize component contributions to sorption equilibria between hydrophobic organic contaminants and different types of soils and sediments exhibiting particle-scale heterogeneity. These characterizations of equilibrium behavior are based on a foundation of experimental observations. Although no similar level of experimental evidence has been accumulated for nonequilibrium sorption behavior, it is of interest to speculate about how the interpretations structured into the DRM model might allow extrapolation of the model to these conditions. 

Equilibrium of heterogeneous processes means that on the interface between media gradients of chemical potentials of individual components are absent, and their sorption and desorption rates are equal. Such equilibrium between media is called heterogeneous equilibrium, and the following equality serves as its criterion at constant temperature and pressure ... 

MacElroy, J. M. D., Seaton, N. A., and Friedman, S. P. (1997) Sorption rate processes in carbon molecular sieves. In Equilibrium and Dynamics of Gas Adsorption on Heterogeneous Solid Surfaces. (W. Rudzinski, W. A. Steele, and G. Zgrablich, ed ). Studies in Surface Sci. and Catal., Col. 104. Elsevier, Amstedam, The Netherlands. 

Finally, K is also a constant (it depends on the temperature only) and it is expressed in (MPa ). K is in direct connection with the adsorptive potentials of the heterogeneous surface [18]. The parameters of Eq. (1) applied to sorption isotherm shown in Figures 6 and 7 are tabulated in Table 2. From the extrapolated data of Eq. (1) to the estimated or sometimes measured geostatic equilibrium pressures can be calculated that coal seams beeing in a depth of 700-1000 m and having a mass about 40 million metric tons may contains 50-60 thousand million cubic meters methane wich is comparable with a good sandstone reservoir. 

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