Adsorption isotherm models column experiments

The competitive adsorption isotherms were determined experimentally for the separation of chiral epoxide enantiomers at 25 °C by the adsorption-desorption method [37]. A mass balance allows the knowledge of the concentration of each component retained in the particle, q, in equilibrium with the feed concentration, < In fact includes both the adsorbed phase concentration and the concentration in the fluid inside pores. This overall retained concentration is used to be consistent with the models presented for the SMB simulations based on homogeneous particles. The bed porosity was taken as = 0.4 since the total porosity was measured as Ej = 0.67 and the particle porosity of microcrystalline cellulose triacetate is p = 0.45 [38]. This procedure provides one point of the adsorption isotherm for each component (Cp q. The determination of the complete isotherm will require a set of experiments using different feed concentrations. To support the measured isotherms, a dynamic method of frontal chromatography is implemented based on the analysis of the response curves to a step change in feed concentration (adsorption) followed by the desorption of the column with pure eluent. It is well known that often the selectivity factor decreases with the increase of the concentration of chiral species and therefore the linear -i- Langmuir competitive isotherm was used ... 

In the gas-phase chromatography experiments, the measure of volatility is assumed to be either a deposition temperature in a thermochromatography column or the temperature in an (isothermal) column at which 50% (T50%) of the desired product (50% chemical yield ) are passing through the gas chromatography column [8]. The values are then correlated with the adsorption enthalpies (AHads). The latter is then related to the sublimation enthalpy (AHsub), a property of the macro-amount using some models, see... 

The hydrodynamic of flow through packed beds has been widely investigated, except the closed end column, which is important from the point of adsorption view. To evaluate the pressurization time from experiments the model of isothermal gas flow in porous materials has been used. The model is based on the following assumptions [1,4] ... 

Identification of the heaviest elements by studying their volatility is a difficult task. Several quantities are associated with this physical phenomenon, which are not necessarily interrelated. Thus, in gas-phase chromatography experiments, a measure of volatility is either a deposition temperature in a thermochromatography column. Tads, or the temperature of the 50% of the chemical yield, Tso%, observed on the outlet of the isothermal column (see Experimental Techniques and Gas-Phase Chemistry of Superheavy Elements , as well as [178]). From these temperatures, an adsorption enthalpy, AT/ads, is deduced using adsorption models [179], or Monte Carlo simulations [ 180,181 ]. The ATfads is supposed to be related to the sublimation enthalpy, ATfsub. of the macroamount (see Thermochemical Data from Gas-Phase Adsorption and Methods of their Estimation ). The usage of a correlation between... 

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