Adsorption process models

The adsorption dynamics of binary and ternary hydrogen mixture in activated carbon and zeolite SA bed was studied by experimentally and theoretically through breakthrough and desorption experiments. Energy balance is an essential element for accurate adsorption process modeling in case of bulk separation. Especially in ternary system, sinusoidal... 

In the discussion of the adsorption kinetics of micellar solutions, different micelle kinetics mechanisms are taken into account, such as formation/dissolution or stepwise aggregation/disaggregation (Dushkin Ivanov 1991). It is clear that the presence of micelles in the solution influences the adsorption rate remarkably. Under certain conditions, the aggregation number, micelle concentration, and the rate constant of micelle kinetics become the rate controlling parameters of the whole adsorption process. Models, which consider solubilisation effects in surfactant systems, do not yet exist. 

Finally to gain a deeper understanding of the bisolute batch adsorption process, models of various significant physical phenomena taking place in the adsorber (e.g., interaction between adsorbates as well as competition) should be incorporated into the present model. Investigations of these phenomena are, however, outside the scope of the present study. 

The BET treatment is based on a kinetic model of the adsorption process put forward more than sixty years ago by Langmuir, in which the surface of the solid was regarded as an array of adsorption sites. A state of dynamic equilibrium was postulated in which the rate at which molecules arriving from the gas phrase and condensing on to bare sites is equal to the rate at which molecules evaporate from occupied sites. 

These functions serve as phenomenological fingerprints of the system, but more Importantly can be related to theoretical models of the adsorption process. 

Oonoeming the interaction i namics of H2 (D ) with N1 surfaces in the first place we have elaborated some rnix tant differences with regcurd to the surface orientation and also with regard bo the mass of the incident molecule. The Lennard-Jcnes potential of Fig. 1 has frequently been used to model the dissociative adsorption process al-thou it provides a descriptlm only in one dimension. Eiqierimental (26) and theoretical (27) studies on H, interaction with metal surfaces suggest that the d th of the molecular potential well (%2 )... 

Spirodela intermedia, L. minor, and P. stratiotes were able to remove Pb(II), Cd(II), Ni(II), Cu(II), and Zn(II), although the two former ions were removed more efficiently. Data fitted the Langmuir model only for Ni and Cd, but the Freundlich isotherm for all metals tested. The adsorption capacity values (K ) showed that Pb was the metal more efficiently removed from water solution (166.49 and 447.95 mg/g for S. intermedia and L. minor, respectively). The adsorption process for the three species studied followed first-order kinetics. The mechanism involved in biosorption resulted in an ion-exchange process between monovalent metals as counterions present in the macrophytes biomass and heavy metal ions and protons taken up from water.112... 

By means of Equations 5 and 6, the adsorption process can be described in terms of the parameters and Ks. Since the effective area of solid surface available to polymer adsorption is not generally known in practice, Ng is a third parameter which must be fitted from experiment and Equations 5 and 6 define a three-parameter model for the process. 

The earlier models (2-5) dealt primarily with the conformation of a single molecule at an interface and apply at very low adsorption densities. More recent treatments (6-10) take into account polymer-polymer and polymer-solvent interactions and have led to the emergence of a fairly consistent picture of the adsorption process. For details of the statistical theories of polymer adsorption, the reader is referred to publications by Lipatov (11), Tadros (12) and Fleer and Scheutjens (13). 

Application of this, or the equivalent statistical models, to actual polymer adsorption processes is further complicated by very imprecise knowledge of the solid surface area which is actually available for polymer adsorption. Surface roughness etc. can certainly be expected to have much more complex effects than on the adsorption of small molecules due to restrictions on... 

Adsorption isotherms obtained from the model have been shown to agree very closely with the predictions of recently published statistical theories (9,13). While there can be no doubt that the more sophisticated, statistical models provide more information on the nature of the adsorption process and the structure of the adsorbed film, because of its simple form, the macroscopic model can offer a powerful tool for the analysis, interpretation and utilization of adsorption data. 

The coagulation, flocculation, and adsorption processes were modeled mathematically using classical coagulation theory as a starting point. The Smoluchowski equation for orthokinetic coagulation in laminar flow is written (18)... 

Mixture phase equilibrium calculations, types of, 24 680-681 Mixture-process design type, 8 399 commercial experimental design software compared, 8 398t Mixtures. See also Multicomponent mixtures Nonideal liquid mixtures acetylene containing, 2 186 adsorption, 2 593-594 adsorption isotherm models,... 

Storti, G., Masi, M., Morbidelli, M. (1993) Modeling of countercurrent adsorption processes. Preparative and production scale chromatography. In Chromatographic Science Series, Vol. 61. Eds. Ganetos, G., Barker, P.E. Marcel Dekker, New York, 673-700. 

Abstract Removal of catechol and resorcinol from aqueous solutions by adsorption onto high area activated carbon cloth (ACC) was investigated. Kinetics of adsorption was followed by in-situ uv-spectroscopy and the data were treated according to pseudo-first-order, pseudo-second-order and intraparticle drfiusion models. It was fotmd that the adsorption process of these compotmds onto ACC follows pseudo-second-order model. Furthermore, intraparticle drfiusion is efiective in rate of adsorption processes of these compoimds. Adsorption isotherms were derived at 25°C on the basis of batch analysis. Isotherm data were treated according to Langmuir and Freundhch models. The fits of experimental data to these equations were examined. 

Three kinetic models were applied to adsorption kinetic data in order to investigate the behavior of adsorption process of adsorbates catechol and resorcinol onto ACC. These models are the pseudo-first-order, the pseudo-second-order and the intraparticle diffusion models. Linear form of pseudo-first-order model can be formulated as... 

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