Sorption thermodynamic analysis

The thermodynamic analysis of these systems played an important role in the interpretation of these data and of the high selectivity. It was found that selective sorption of complex organic ions is accompanied by an increase in the entropy of the system (Table 6). 

J.W. Dijkstra, D. Jansen, R.W. van den Brink, Sorption-enhanced hydrogen production for pre-combustion C02 capture thermodynamic analysis and experimental results, Int. J. Greenhouse Gas Control. Vol. 1 (2007) 170-179. 

In Section I we introduce the gas-polymer-matrix model for gas sorption and transport in polymers (10, LI), which is based on the experimental evidence that even permanent gases interact with the polymeric chains, resulting in changes in the solubility and diffusion coefficients. Just as the dynamic properties of the matrix depend on gas-polymer-matrix composition, the matrix model predicts that the solubility and diffusion coefficients depend on gas concentration in the polymer. We present a mathematical description of the sorption and transport of gases in polymers (10, 11) that is based on the thermodynamic analysis of solubility (12), on the statistical mechanical model of diffusion (13), and on the theory of corresponding states (14). In Section II we use the matrix model to analyze the sorption, permeability and time-lag data for carbon dioxide in polycarbonate, and compare this analysis with the dual-mode model analysis (15). In Section III we comment on the physical implication of the gas-polymer-matrix model. 

The value of S(Q) at zero Q value cannot be determined experimentally on the same instrument that is used to measure diffusivities there are not enough points at small Q in Fig. 8b. However, the S(Q) scale, which is given in Fig. 8b in arbitrary units, can be renormalized. At infinite dilution, S(0) should be equal to one (hke in a gas), and sorption thermodynamics also imply that the thermodynamic correction factor should be equal to one, so that Eq. 38 will be fulfilled. On the other hand, at high concentrations, F increases while S(0) goes down. In Fig. 8b, r is equal to 6.6 for a concentration of 14 CF4 per u.c. so that S(0) should go down to 0.15. A more quantitative analysis has been recently performed for n-hexane and n-heptane in sihcalite [36] where the inverse of the thermodynamic factor, calculated from S(Q) was found to be in good agreement with configurational-bias Monte Carlo (CBMC) simulations. 

CON Conforti, R.M. and Barbari, T.A., A thermodynamic analysis of gas sorption-desorption hystereses in glassy polymers. Macromolecules, 26, 5209, 1993. 

G.G. Lipscomb, Unified Thermodynamic Analysis of Sorption in Rubbery and Glassy Materials. AlChE Journal,... 

Cobden, P.D., Van Beurden, R, Reijers, H.T.J. et al. (2007) Sorption enhanced hydrogen production for pre-combustion CO2 capture Thermodynamic analysis and experimental results. International Journal of Greenhouse Gas Control, 1,170-179. 

Lipscomb, G.G., Unified thermodynamic analysis of sorption in rubbery and glass materials, AlChE J., 36(10), 1505-1516(1990). 

Solids characterization may be performed by Si 9 NMR or XRD. With Si NMR, changes in the crystal dimensions due to sorption have been observed (refs. 1-3). Sorbed phase characterization can be studied by volumetric sorption. Thermodynamically simple molecules (e.g., spherical and small) at low temperatures arc used to study pore volume and sizes. A novel, automated, low pressure sorption instrument (Omicron Tech., Berkeley Heights, NJ, USA) has greatly simplified the analysis of zeolites. The technique has recently been named High Resolution Adsorption (HRADS). 

Selectivity of sorption of organic ions by crosslinked polyelectrolytes in competition with small ions, in particular with metal ions, should be considered on the basis of the analysis of thermodynamic relationships of ion exchange. 

The selectivity of ion exchange Ks can easily be determined experimentally for the simplest systems of exchange between monovalent ions. The value of Ks may be used for analysis of thermodynamic functions AG°, AH0 and AS0, of sorption selectivity... 

Modeling hydrogeochemical processes requires a detailed and accurate water analysis, as well as thermodynamic and kinetic data as input. Thermodynamic data, such as complex formation constants and solubility products, are often provided as data sets within the respective programs. However, the description of surface-controlled reactions (sorption, cation exchange, surface complexation) and kinetically controlled reactions requires additional input data. 

The proposed form of data presentation became highly popular and opportune in gas chromatography. Up to the present, some thousand references to the Kovat s work [1] have been known. The RI values are proportional to the free energies of sorption this is their thermodynamic interpretation. Further development of the RI concept was aimed at its application to nonisothermal conditions of gas chromatographic (GC) analysis. For linear temperature programming regimes (which are characterized by two variables initial temperature, Tq, and rate of its increase, r, deg X min ), the linear relationship (3) does not hold. In some partial cases, other linear dependence seems more precise for the retention time approximation ... 

By a combined gravimetric and i.r. technique, spectra of lysozyme protein films have been recorded during sorption isotherms at constant water content h (mg per mg dry protein) in the range 0Computer-aided differential analysis shows the effect of progressive hydration on some significant sites of the protein such as the ionizable acidic side-chains and the backbone amide carbonyls, as well as the spectrum of the absorbed water itself. In order to derive thermodynamic properties of these sites, the... 

The cost and performance of product/equipment/system or the mode of application are always of concern in controlling process efficiency. Therefore, the sorption capacity and required contact time are two of the most important parameters to understand in a sorption process. Equilibrium analysis is fundamental to evaluate the affinity or capacity of a sorbent. However, thermodynamic data can only predict the final state of a system from an initial... 

Mo is removed from sulfidic waters by sorption of thiomolybdate ions on sinking particles. Rather, they postulated that Mo is incorporated into an Fe-Mo sulfide mineral phase that precipitates in euxinic waters below the depth where FeS becomes supersaturated and that solubility of this phase controls the Mo concentration in the sulfidic water column. This may be the same Fe-Mo phase that was experimentally precipitated by Flelz et al. [35] and was shown by EXAFS analysis to contain Mo tetrahedrally coordinated by S, as appears to be the case in some samples of black shale. To understand better the conditions in which Mo might precipitate as an Fe-Mo sulfide, Helz et al. [17] used thermodynamic methods to calculate the solubility of the putative sulfide phase as a function of pH, [Mo], and [H2S]. Their calculations predicted that only a narrow range of pH-[Mo]-[H2S] conditions will result in complete insolubility of Mo. Their model succeeded in predicting the Mo concentrations in deep waters in several other modern anoxic and euxinic areas. Helz et al. [17] concluded that the complete removal of Mo from the water column in the Black Sea is not representative of the general behavior of Mo in euxinic basins over time, but is instead the exception to the rule. 

The performed analysis of the literary data allows making a conclusion that a complex investigation of interrelation between the structure, thermodynamic characteristics and sorption properties of polysaccharides makes it possible to purposefully select effective means of BAS supply to a human organism. 

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