Characterization breakthrough curves

For the characterization of wave shape and breakthrough curves, three methods are popular. The MTZ method [Michaels, Ind. Eng. Chem., 44,1922 (195 ] measures the breadth of a wave between two chosen concentrations (e.g., c = 0.05 and 0.95 orc = 0.01 and 0.99). Outside of a laboratory, the measurement of full breakthrough curves is rare, so the breadth of the MTZ is often estimated from an independently determined stoichiometric capacity and a measured small... 

This phenomenon is illustrated by a breakthrough curve, as presented in Fig. 4. A breakthrough curve is characterized by different parameters ... 

When adsorption isotherms are determined by breakthrough experiments (see below), the acquired data can be directly taken for the detector calibration. Breakthrough curves should be recorded after injecting well-characterized solutions into the plant without the column. This required considerably less sample to reach complete saturation. Since the plateau concentrations are the known injected feed concentrations, a plot of Cfeed versus the detector signal u provides the sought-after relationship and a calibration function can be easily fitted to these values. 

Table 1.13 compiles the benzene and toluene adsorption capacities for pristine AC obtained by numerical integration of breakthrough curves similar to those of Figure 1.36. It includes the porous characterization of commercial samples developed for removal of hydrocarbons as well as of ACs prepared by different activation methods and activating agents. 

Due to both common knowledge and related model calculations, at a technical scale that is characterized by L/2Rp > 200, axial dispersion as compared with convection contributes little to overall mass and heat transfer. Neglecting both steps in the calculation of breakthrough curves causes deviations within the order of magnitude of numerical errors for the solution of the resulting equations for convection. Further simplification is possible by lumping parameters. A comparison of mass transport resistances in a pellet leads to the following overall resistance [101] ... 

Breakthrough curves can be considered as the last of the essential characterizations of an activated carbon. Equilibrium isotherm data provide information of the capacity of a carbon. Next, the kinetics of the adsorption processes must be known, giving information of the rates at which adsorptives are adsorbed by the adsorbent. Finally, the performance of a carbon (so characterized) in an industrial situation can be simulated by making use of the breakthrough curves. 

In a subsequent paper, Lavanchy and Stoeckli (1999) confirmed the agreement between experimental and predicted isotherms based on the use of the MPD equations to characterize the activated carbons. Note Myers-Prausnitz (MP) theory is an approach to characterize the carbons in association with the DA equation, hence (MPD).) However, the MPD approach is not valid for the breakthrough curve of 2-chloropropane when the carrier gas is air that contains moisture (water vapor). This is a consequence of the immisci-bility of the adsorbed water and 2-chloropropane. 

The contents of this chapter summarize the several methodologies used to characterize the porosity of activated carbon. The isotherms of the N2 (77 K), CO2 (273 K), H2O (298 K), making use of DR and BET equations, together with a-plots, in association with enthalpies of immersion, characterize porosity in activated carbon. Equilibria data are complemented by the kinetic data from breakthrough curves. 

Liquid chromatography breakthrough curves have been used to characterize the porosity of a dealuminated Y zeolite, and more precisely the mesopores in cavities and the cylindrical mesopores. The methodology presented in this paper shows that the use of several probe molecules with different molecular size and adsorption strength can give an estimation of the zeolite porosity. 

The methodology presented herein is, to our knowledge, the first attempt to characterize the different porosities of dealuminated Y zeolites by breakthrough curves. Even if the results are not fully satisfactory, these first sets of experiments carried out on two pelletized Y zeolites can lead to the following conclusions. 

In this section, a stochastic compartmental model is employed to estimate the number of compartments (necessary to characterize the flow) and the intensities of forward and backward flows between compartments in an open-flow adsorber without adsorbate. In addition, this model and the linear batch model are combined into one for predicting breakthrough curves in an open-... 

In the first polymer run, a 2.0-PV slug of 187-ppm polymer solution was displaced through the core at a velocity of 3.28 ft/D (52.77 ml/hr). The normalized concentration, the concentration of the effluent stream divided by the injected concentration (C/C, ), is plotted vs pore volumes injected in Fig. 3. Breakthrough (C/C = 0.5) occurred at 1.205 PV. The effluent curve is characterized by a steep front followed by a long tail where the concentration increases very slowly. The maximum polymer concentration attained in the column effluent was 179 ppm. 

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