Sorption equilibrium parameter

The equilibrium concentrations c and C2 can be calculated using the pressure, p, and the sorption equilibrium parameter, S ... 

Because of the similarity of transport in biotilms and in stagnant sediments, information on the parameters that control the conductivity of the biofilm can be obtained from diagenetic models for contaminant diffusion in pore waters. Assuming that molecular diffusion is the dominant transport mechanism, and that instantaneous sorption equilibrium exists between dissolved and particle-bound solutes, the vertical flux ( ) through a stagnant sediment is given by (Berner, 1980)... 

The calculated parameters of the Freundlich sorption isotherms are listed in Table 10.4. Theoretically, the higher the sorption intensity parameter (1/n), the lower the binding affinity of soil with metals. The equilibrium partition coefficient (k) is positively related to metal sorption capacity of soils. The sorption capacities and... 

There is an increase in the rate of diffusion and the maximum solvent uptake with an increase in temperature. Therefore, in the process of sorption or solvent uptake of rubbery polymer, when the absorption obtain the equilibrium, sorption constant parameter could be determined from the amount of liquid sorbed by a given mass of the polymer, the equilibrium sorption constant for the samples at different temperature has been computed as ... 

The calculation of the sorption equilibrium proceeds by means of eqs. (16) and (17). The characteristic parameters, q, E and AS, are obtained by fitting to data that were either experimentally obtained or taken from literature. Although utilization of eq. (16) with single component sorption equilibrium data may lead to extreme deviations, its applicability had been proven [63]. 

In this article we report i) the measurement of sorption equilibrium data of nC,-, and nCy in 5A zeolite pellets on a flow microbalance ii) The measurement of intraparticle diffusivity of nCs and nCc on 5A zeolite pellets with crystals of different size by ZLC and gravimetry and iii) The development of a mathematical model in order to predict the behavior of fixed bed and cyclic adsorption processes, iv) The prediction of breakthrough curves of propane/propylene and n/iso-paraffins mixtures in a fixed-bed adsorber based on a model including parameters independently measured, iv) Study of cyclic adsorption processes as Pressure Swing Adsorption (PSA) / Vacuum Swing Adsorption (VSA) and Temperature Swing Adsorption (TSA) for the separation of propane /propylene mixtures and n/iso-paraffins mixtures. 

Finally, when aK/y 1, the sheet will track the sorption equilibrium corresponding to the external humidity change. In the baseline case, this parameter group is equal to 0.14. Again, significant lag between the equilibrium values and the actual observed moisture content is seen. The condition will be satisfied better if sheet thickness is smaller or the mass transfer coefficient is enhanced or the ramp change occurs slower. Any of these will result in the sheet following equilibrium more closely. Table 7 shows example conditions under which each of these models is applicable. 

More recently, new solutions to improve the separation of mixtures of dissolved heavy metals by means of parametric pumping with variation of pH have been presented for IX resins [45], The most important property of this method is the fact that it is a regenerant-free separation or ion exchange process. Separation is possible if a parameter of substantial influence on the sorption equilibrium is varied. 

The transport of substituted benzenes through blends of thermoplastic polyurethane (TPU) and NR at 30, 50, and 70 °C was studied by A1 Minnath et al Results indicated that the equilibrium solvent uptake in the blends decreased with an increase in the concentration of TPU. The mechanism of diffusion of the solvents was found to deviate from the normal Fickian trend. The sorption data obtained were used to estimate the transport coefficient, and various sorption kinetic parameters. 

Plots of permeability coefficients versus (1 + bpY should be linear. The intercept and slope of the line correspond to koDp and CnbDn, respectively. Once the equilibrium parameters from the dual mode sorption theory are known, the two diffusion coefficients. Do and D//, can be determined. 

The algorithm we used for solvent/polydisperse polymer equilibria calls for only one solvent/polymer interaction parameter. The interaction parameter (pto) i ed in the algorithm can be determined from essentially any type of ethylene/polyethylene phase equilibrium data. Cloud-point data have been used (18). while Cheng (16) and Harmony ( ) have done so from gas sorption data. 

A procedure for characterizing the rates of the volume change of gels has not been uniformly adopted. Often, the kinetics are simply presented as empirical sorption/desorption curves without quantitative analysis. In other cases, only the time required for a sample of given dimensions to reach a certain percentage of equilibrium is cited. One means of reducing sorption/desorption curves to empirical parameters is to fit the first 60% of the sorption curve to the empirical expression [119,141]... 

Fowle and Fein (1999) measured the sorption of Cd, Cu, and Pb by B. subtilis and B. licheniformis using the batch technique with single or mixed metals and one or both bacterial species. The sorption parameters estimated from the model were in excellent agreement with those measured experimentally, indicating that chemical equilibrium modeling of aqueous metal sorption by bacterial surfaces could accurately predict the distribution of metals in complex multicomponent systems. Fein and Delea (1999) also tested the applicability of a chemical equilibrium approach to describing aqueous and surface complexation reactions in a Cd-EDTA-Z . subtilis system. The experimental values were consistent with those derived from chemical modeling. 

The main goal of this chapter is to review the most widely used modeling techniques to analyze sorption/desorption data generated for environmental systems. Since the definition of sorption/desorption (i.e., a mass-transfer mechanism) process requires the determination of the rate at which equilibrium is approached, some important aspects of chemical kinetics and modeling of sorption/desorption mechanisms for solid phase systems are discussed. In addition, the background theory and experimental techniques for the different sorption/ desorption processes are considered. Estimations of transport parameters for organic pollutants from laboratory studies are also presented and evaluated. 

EXTRACT and O-METHYLATED EXTRACT. The sorption of benzene by the extract and the O-methylated extract is characterized by a rapid, initial uptake followed by a very slow approach to equilibrium. Such sorption behavior is very similar to that of glassy polymers. Thus we have chosen to interpret the sorption curves shown in Figures 2 and 3 in terms of the Berens-Hopfenberg model developed for the sorption of organic vapors into glassy polymers.(lS) By doing so, we attempt to correct the total sorption values for surface adsorption in order to calculate x parameters. 

The development of mixture sorption kinetics becomes increasingly Important since a number of purification and separation processes involves sorption at the condition of thermodynamic non-equilibrium. For their optimization, the kinetics of multicomponent sorption are to be modelled and the rate parameters have to be identified. Especially, in microporous sorbents, due to the high density of the sorption phase and, therefore, the mutual Influences of sorbing species, a knowledge of the matrix of diffusion coefficients is needed [6]. The complexity of the phenomena demands combined experimental and theoretical research. Actual directions of the development in this field are as follows ... 

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