Sorption equilibria

The intermediate values correspond to the approximation of the quasiequilibrium conditions of sharpening of zone boundaries. At the same time, selective displacement in equilibrium sorption dynamics conception is carried out with the... 

It is often of industrial interest to be able to predict the equilibrium sorption of a gas in a molten polymer (e.g., for devolatilization of polyolefins). Unfortunately, the Prigogine-Flory corresponding-states theory is limited to applications involving relatively dense fluids 3,8). An empirical rule of thumb for the range of applicability is that the solvent should be at a temperature less than 0.85 Tp, where Tp is the absolute temperature reduced by the pure solvent critical temperature. 

Equilibrium Sorption Values of Different Nanocomposite-Solvent Systems... 

Igwe, C.J. and Abia, A.A., Equilibrium sorption isotherm studies of Cd(II), Pb(II) and Zn(II) ions detoxification from wastewater using unmodified and EDTA-modified maize husk, Electronic Journal of Biotechnology, 10 (4), 536-548, 2007. 

Sorption. Capture of neutral organics by non-living particulates depends on the organic carbon content of the solids (9). Equilibrium sorption of such "hydrophobic" compounds can be described by a carbon-normalized partition coefficient on both a whole-sediment basis and by particle size classes. The success of the whole-sediment approach derives from the fact that most natural sediment organic matter falls in the "silt" or "fine" particle size fractions. So long as dissolved concentrations do not exceed 0.01 mM, linear isotherms (partition coefficients) can be used. At higher concentrations, the sorptive capacity of the solid can be exceeded, and a nonlinear Freundlich or Langmuir isotherm must be invoked. 

Figure 12.2 The effect of salt on the equilibrium sorption of basic dyes on acrylic fibres [54,55]...

Loukidou et al. (2005) fitted the data for the equilibrium sorption of Cd from aqueous solutions by Aeromonas caviae to the Langmuir and Freundlich isotherms. They also conducted, a detailed analysis of sorption rates to validate several kinetic models. A suitable kinetic equation was derived, assuming that biosorption is chemically controlled. The so-called pseudo second-order rate expression could satisfactorily describe the experimental data. The adsorption data of Zn on soil bacterium Pseudomonas putida were fit with the van Bemmelen-Freundlich model (Toner et al. 2005). 

Offshore Grand Haven sediment, batch equilibrium-sorption isotherm, Voice Weber 1985)... 

Depending on the electron affinity of the catalyst, one of these two routes predominates. The dependence of the hydroperoxide decomposition rate on [ROOH] is in agreement with the conception of preliminary equilibrium sorption of hydroperoxide on the catalyst surface (Me2PhCOOH, AgO, 16m2 L 343 K) [263]). The equilibrium constant was estimated to be K 1 mol L and effective rate constant of described ROOH decomposition is /cis = 70s I[263]. 

For a species affected only by an equilibrium sorption reaction, if the species sorbed concentration C5. depends directly on its dissolved concentration Q, the reaction rate is,... 

If the step is only equilibrium controlled, a lumped analysis of both fluid and solid phase is possible and the corresponding nonlinear wavefront analysis is straight forward too. Analysis of propagation speed data yield information about the relevant equilibrium sorption mechanism (7). The different form of the transients when a reaction step has been stimulated, is discussed in the Appendix. 

Walters and Guiseppe-Elle [108] studied the sorption of 2,3,7,8-tetrachlorodibenzo-p-dioxin to soils from aqueous methanol mixtures and evaluated the applicability of the cosolvent theory to such sorption. Sorption kinetics were influenced by the fraction of methanol in the liquid phase and the soil type. Linear equilibrium sorption isotherms were... 

O Connor and Connolly [107] found that equilibrium sorption partition coefficients of several pollutants into Texas River sediments declined as sediment concentration increased in isothermal studies. This has been interpreted as an indication that colloids in solution were competing with the sediment for sorbate and that the concentration of colloids increased as the concentration of sediment increased. 

Construction and use of adsorption isotherms from equilibrium sorption data has been employed by numerous researchers to describe adsorption of organic pollutants on a solid matrix [131-137]. An isotherm represents a relation between the amount of solute (i.e., the pollutant of interest) adsorbed per unit weight of solid adsorbent (i.e., soil, sediment) and the solute concentration in solution at equilibrium. 

Whereas batch equilibrium tests are designed to study equilibrium sorption of solid phase particles with various pollutants, singly or in combination with other pollutants, solid phase column-leaching tests study both sorption and diffusion of organic pollutants through the subsurface environment [10,11,127, 141,142]. 

Of the various equilibrium and non-equilibrium sorption isotherms or sorption characteristics models, the most popular are the Langmuir and Freundlich models. The correct modeling of an adsorbate undergoing both transport and adsorption through a clay soil-solid system necessitates the selection of an adsorption isotherm or characteristic model which best suits the given system. The use of an improper or inappropriate adsorption model will greatly affect the... 

Most sorption/desorption kinetic models fit the data better by including an instantaneous, non-kinetic fraction described by an equilibrium sorption constant. 

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