Sorption experimental results

Generally the above expressions adequately describe sorption isotherms of the type reported in Fig. 1, giving good agreement with experimental results in non-... 

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. 

Williams, M.D., Adams, W.J., Parkerton, T.F., Biddinger, G.R., and Robillard, K.A. Sediment sorption coefficient measurements for four phthalate esters experimental results and model theory, firwro/r. Toxicol. Chem., 14(9) 1477-1486,1995. 

With particular reference to reverse osmosis systems involving cellulose acetate membranes and aqueous solutions, the membrane material has both polar and nonpolar character, and the solvent, of course, is polar. When these two components of the reverse osmosis system are kept constant, preferential sorption at the membrane-solution interface, and, in turn, solute separation in reverse osmosis, may be expected to be controlled by the chemical nature of the solute. If the latter can be expressed by appropriate quantitative physicochemical parameters representing polar-, steric-, nonpolar-, and/or ionic-character of the solutes, then one can expect unique correlations to exist between such parameters and reverse osmosis data on solute separations for each membrane. Experimental results confirm that such is indeed the case (18). 

It is the purpose of this article to point out the need for caution in the interpretation of many experimental results so far published in the field of catalysis and for a critical attitude toward the problem of sorption of gases, which may include adsorption on the surface as well as absorption into the interior of the structure, and may easily lead to faulty conclusions. 

The purpose of most experimental studies of diffusion is to obtain accurate diffusion coefficients as a function of temperature, pressure, and composition of the phase. For this purpose, the best approach is to design the experiments so that the diffusion problem has a simple anal3hical solution. After the experiments, the experimental results are compared with (or fit by) the anal3hical solution to obtain the diffusivity. The method of choice depends on the problems. The often used methods include diffusion-couple method, thin-source method, desorption or sorption method, and crystal dissolution method. 

Equilibrium thermodynamics is one of the pillars supporting the safety analyses of radioactive waste repositories. Thermodynamic constants are used for modelling reference porewaters, calculating radionuclide solubility limits, deriving case-specific sorption coefficients, and analysing experimental results. It is essential to use the same data base in all instances of the modelling chain in order to ensure internally consistent results. 

Therefore, based on available literature, the following sorption results were expected (l) as a result of the smectite minerals, the sorption capacity of the red clay would be primarily due to ion exchange associated with the smectites and would be on the order of 0.8 to I.5 mi Hi equivalents per gram (2) also as a result of the smectite minerals, the distribution coefficients for nuclides such as cesium, strontium, barium, and cerium would be between 10 and 100 ml/gm for solution-phase concentrations on the order of 10"3 mg-atom/ml (3) as a result of the hydrous oxides, the distribution coefficients for nuclides such as strontium, barium, and some transition metals would be on the order of 10 ml/gm or greater for solution-phase concentrations on the order of 10 7 mg-atom/ml and less (U) also as a result of the hydrous oxides, the solution-phase pH would strongly influence the distribution coefficients for most nuclides except the alkali metals (5) as a result of both smectites and hydrous oxides being present, the sorption equilibrium data would probably reflect the influence of multiple sorption mechanisms. As discussed below, the experimental results were indeed similar to those which were expected. 

In this case, the estimate based only onfocKioc is very close to the experimental result, indicating that for high substrate concentrations partitioning into POM is the dominant sorption mechanism. 

In this review, we focus on the information at an atomic/molecular level that is obtainable via the different techniques. The precise methods and techniques used are not extensively discussed instead we summarize the relevant details and direct the reader toward key references. Nor do we review the potentials that are used in the classical simulations of sorption and diffusion. Derivation and evaluation of these parameters require extensive comparison with detailed spectroscopic data and are beyond the scope of this work. Similarly, the volume of experimental results that may be used in comparison to the calculations is vast. We use representative data taken largely from reviews or books. 

Hope et al. (116) presented a combined volumetric sorption and theoretical study of the sorption of Kr in silicalite. The theoretical calculation was based on a potential model related to that of Sanders et al. (117), which includes electrostatic terms and a simple bond-bending formalism for the portion of the framework (120 atoms) that is allowed to relax during the simulations. In contrast to the potential developed by Sanders et al., these calculations employed hard, unpolarizable oxygen ions. Polarizability was, however, included in the description of the Kr atoms. Intermolecular potential terms accounting for the interaction of Kr atoms with the zeolite oxygen atoms were derived from fitting experimental results characterizing the interatomic potentials of rare gas mixtures. In contrast to the situation for hydrocarbons, there are few direct empirical data to aid parameterization, but the use of Ne-Kr potentials is reasonable, because Ne is isoelectronic with O2-. 

In the first chapter, Bates and van Santen summarize the theoretical foundations of catalysis in acidic zeolites. Being the most important crystalline materials used as catalysts, zeolites have been the obvious starting point for applications of theory to catalysis by solids and surfaces. Impressive progress has been made in the application of theory to account for transport, sorption, and reaction in zeolites, and the comparisons with experimental results indicate some marked successes as well as opportunities for improving both the theoretical and experimental foundations. 

Experimental results presented in this work and in the literature are inconsistent with the assumptions and the physical interpretations implicit in the dual-mode sorption and transport model, and strongly suggest that the sorption and transport in gas-glassy polymer systems should be presented by a concentration-dependent model ... 

Akratanakul, S., Boersma, L., and Klock, G. O. (1983). Sorption processes in soils as influenced by pore water velocity. 2. Experimental results. Soil Sci. 135, 331-341. 

Equation 6 was used to predict experimental measurements of binary mixtures of adsorbents for sorption of Cs(I) and Sr(II) from measurements on the individual minerals. (11) For some of the cases investigated, the distribution coefficients could be calculated with considerable precision from measurements on the individual minerals. In other cases, there appeared to be interaction between the minerals. However, these experimental results appear to confirm Equations 5 and 6 for cases where the sorbents do not interact. 

Our experimental results are in a good agreement with results of other authors [3] showed that nanotubes have the best hydrogen sorption ability among known carbon nanostructures. 

Because of the assumed dual sorption mechanism present in glassy polymers, the explicit form of the time dependent diffusion equation in these polymers is much more complex than that for rubbery polymers (82-86). As a result exact analytical solutions for this equation can be found only in limiting cases (84,85,87). In all other cases numerical methods must be used to correlate the experimental results with theoretical estimates. Often the numerical procedures require a set of starting values for the parameters of the model. Usually these values are shroud guessed in a range where they are expected to lie for the particular penetrant polymer system. Starting from this set of arbitrary parameters, the numerical procedure adjusts the values until the best fit with the experimental data is obtained. The problem which may arise in such a procedure (88), is that the numerical procedures may lead to excellent fits with the experimental data for quite different starting sets of parameters. Of course the physical interpretation of such a result is difficult. 

The resulting curve is termed the absorption (or desorption) curve, or more generally the sorption curve. However, in order to interpret correctly experimental results in terms of Eq. (1) it is necessary to plot M lf), the weight of sorbed penetrant per unit volume of the swelling or deswelling film, against This requirement arises from the fact that... 

Henzler (1982) was able to correlate the same experimental results by using the dimensionless group Y = (kLaL/v)(ul/g)113 as ordinate and X = PJ(Vpgv) as abscissa. The dimensionless group Y represents the sorption number for bubble columns, while X represents the ratio of the mechanical power of the stirrer to the hydraulic power of the gas throughput. The sorption number Y also allows comparison between mixing tanks and bubble columns (Henzler... 

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