Calculation methods for multicomponent adsorption equilibria

Abstract

The knowledge of multicomponent adsorption equilibria is of great importance for the industrial design and application of adsorptive purification and separation processes. As the experimental determination of the required data is time-consuming and costly, theoretical help is desirable. This contribution presents and assesses the most common theoretical approaches to the calculation of multicomponent adsorption equilibria. The models are based on the assumption of an adsorbed solution, extension of the volume filling of micropores theory or statistical thermodynamics. These models are applied to different adsorptiveladsorbent systems with ideal and non-ideal equilibrium behaviour. It is established that, at low coverages of adsorbent surfaces, all theories provide good estimates of the adsorbed phase composition and total loading while, at high saturations, no model is completely satisfactory.

Derivation and Application of a Jovanovic–Freundlich Isotherm Model for Single-Component Adsorption on Heterogeneous Surfaces

“…This result is again similar to the one reported previously (8). The values obtained for the hetero-concentrations (31). Thus, high concentrations is the range in which it is desirable to find models accounting well for geneity parameter of tetrachloroethylene are different from those of all the other chlorinated hydrocarbons, which may single-component data, provided that these models can be used within the framework of the adsorbed solution theory be explained by the fact that it is the only unsaturated commodels.…”

“…For example, the extension of the model to describe competitive adsorption can be accomplished using models of the adsorbed solution theory (31) or the method C(z) Å RTF(e). The integral equation [1] can be solved analytically with Considering Eqs.…”

“…In compensation, the method introduces new parameters that must be evaluated from binary equilibrium data, thus eliminating the possibility of predicting multicomponent equilibrium isotherms from single-component data. This limitation is relative, however, because multicomponent data must always be generated, as tests of the model and, in the case of actual adsorbed solution theory models, for correlating adsorbed phase activity coefficients (31).…”

Isotherm Models for Localized Monolayers with Lateral Interactions. Application to Single-Component and Competitive Adsorption Data Obtained in RP-HPLC

“…38 Other models which can account for these additional nonideal effects should be tested, such as the multicomponent heterogeneous models with and without lateral interactions 39 and the adsorbed solution theory models. 40…”

Evaluating mixture adsorption models using molecular simulation

“…This approach is popular due to the fact that it relies solely on the isotherms of the pure components in the fluid mixture and is amenable to rapid solution using numerical techniques. IAST has been used extensively to describe adsorption from multicomponent mixtures in zeolites and other adsorbents, including mixtures of alkanes, CO 2 , CH 4 , and N 2 . Extensions to IAST include the real adsorbed solution theory and the non‐ideal AST, which attempts to account for nonideal behavior of the adsorbed phase by correlating activity coefficients from binary adsorption data or assumptions about the distribution of sites, respectively.…”