Breakthrough curve column

Vq is the column holdup volume (including the extra column breakthrough curve is the thick volume)... 

Figure 6. Nonisothermal column breakthrough curve for water (37 % R.H.) from air on Laporte alumina at 26° C.

Laboratory column experiments were used to identify potential rate-controlling mechanisms that could affect transport of molybdate in a natural-gradient tracer test conducted at Cape Cod, Mass. Column-breakthrough curves for molybdate were simulated by using a one-dimensional solute-transport model modified to include four different rate mechanisms equilibrium sorption, rate-controlled sorption, and two side-pore diffusion models. The equilibrium sorption model failed to simulate the experimental data, which indicated the presence of a ratecontrolling mechanism. The rate-controlled sorption model simulated results from one column reasonably well, but could not be applied to five other columns that had different input concentrations of molybdate without changing the reaction-rate constant. One side-pore diffusion model was based on an average side-pore concentration of molybdate (mixed side-pore diffusion) the other on a concentration profile for the overall side-pore depth (profile side-pore diffusion). 

Many one-dimensional solute-transport models have been developed and used to analyze column data. For a recent review, see Grove and Stollenwerk (13). Four different models were used in the study discussed in this article to simulate the shape of the column-breakthrough curves. All four models contain a one-dimensional solute-transport equation and use the Freundlich equation to describe sorption. They differ in the rate mechanism that is assumed to control transport of Mo(VI) from flowing phase to solid surface. The essential features of each model are summarized in Table III. 

Finite-difference techniques were used to compute numerical solutions as column-breakthrough curves because of the nonlinear Freundlich isotherm in each transport model. Along the column, 100 nodes were used, and 10 nodes were used in the side-pore direction for the profile model. A predictor-corrector calculation was used at each time step to account for nonlinearity. An iterative solver was used for the profile model whereas, a direct solution was used for the mixed side-pore and the rate-controlled sorption models. 

The four potential rate mechanisms were evaluated by calculating column-breakthrough curves for various parameter sets to obtain the most accurate correlation between observed column-breakthrough curves and calculated concentration data. The parameters pbf and pbs for the mixed side-pore and profile side-pore diffusion models were estimated from the 0.043 mmol/1 breakthrough curves. Simulations at other concentrations were made by changing only the solution concentration value in the Freundlich equation. Physical and chemical parameters common to all four models are listed in Table II. Results are for 0.096-, 0.043-, 0.01- and 0.0016-mmol/l columns. 

The effluent concentration history is the breakthrough curve, also shown in Fig. 16-3. The effluent concentration stays at or near zero or a low residual concentration until the transition reaches the column outlet. The effluent concentration then rises until it becomes unacceptable, this time being called the breakthrough time. The feed step must stop and, for a regenerative system, the regeneration step begins. 

A single-column system for liquid-phase carhon adsorption is used in situations where the following conditions prevail laboratory testing has indieated that the breakthrough curve will be steep the extended lifetime of the earbon at normal operating conditions results in minor replacement or regeneration eosts the eapital... 

A breakthrough curve with the nonretained compound was carried out to estimate the axial dispersion in the SMB column. A Peclet number of Pe = 000 was found by comparing experimental and simulated results from a model which includes axial dispersion in the interparticle fluid phase, accumulation in both interparticle and intraparticle fluid phases, and assuming that the average pore concentration is equal to the bulk fluid concentration this assumption is justified by the fact that the ratio of time constant for pore diffusion and space time in the column is of the order of 10. ... 

A) Sorption breakthrough curves for U(VI) fouled with Fe(lll) on an anion-exchange resin column. 

Figure 7 Regeneration of ODA-clinoptilolite columns loaded with chromate by means of 2% NaCI and 2% Na2S04 aqueous solutions and breakthrough curves for ODA- clinoptilolite in 0.5 mM/L chromate solution by 30 BV/hr and 15 BV/hr in downflow mode (from the left)...

Fig. 7 presents partial results of dynamic regime experiments for chromate adsorption and desorption by ODA-clinoptilolite. As shown by breakthrough curves, ODA-clinoptilolite column quantitatively removes chromate species from simulated waste water , apparently more efficiently by lower flow rate. Consequently to similar configuration of chromate and sulfate molecules, such loaded column was more efficient to regenerate with Na2S04 than NaCl solution, as elution curves at the Fig. 7 illustrate. 

Figure 8. Regeneration of ODA-clinoptilolite column loaded with arsenate by means of 2% NaCl aqueous solution and breakthrough curves for ODA-clinoptilolite in arsenate solution of co = 25 mg/L repeated cycle after regeneration, first cycle breakthrough curve on Pb-clinoptilolite (from the left).

A typical breakthrough curve was observed for the column filled with Zr-loaded activated carbon after about 8000 pore volumes. This correspond to a uptake of 2.8 mg As/g. The concentrations in the outlet of the column with Absorptionsmittel 3 increased after about 4000 pore volumes, but no typical breakthrough curve was observed. The uptake until this point was only 2 mg As/g that is much lower than it was determined in the batch experiments. An explanation for this early increasing of the concentrations may be the high flow rate in comparison of the slow kinetics. The best results gave the column filled with the granular iron hydroxide. No breakthrough was observed up to now (12,000 pore volumes) and an uptake of about 2 mg As/g could be measured. The arsenite concentrations in the outlet of all three columns were very low and indicate an oxidation reaction. 

Figure /. Breakthrough curves of arsenate and pH profiles of column effluents during adsorption from feeds in t he absence and presence of foreign anions.

Figure 4. Breakthrough curves of Pb(II) in the adsorption of Pb(II) by FPS-f and FP-f packed columns. Column 1.5 ml of wet fiber (0.4 g in dry state), feeding solution 0.01 M lead nitrate. Flow rates in space velocity (h-1) are denoted on the figure.

The breakthrough curves measured for the monolithic columns with different proteins are very sharp and confirm again the fast mass transport kinetics of the monoliths [133, 134]. The frontal analysis used for the determination of the breakthrough profile can also be used for calculation of the dynamic capacity of the column. For example, the capacity for the 60x16mm i.d. monolith at 1% breakthrough is 324 mg of ovalbumin and represents the specific capacity of 40.0 mg/g of separation medium or 21.6 mg/ml of column volume. 

Fig. 6. The general column-leaching cell methods, with their breakthrough curves...

The concentration of any contaminant(s) from highway C R materials appearing in the effluent from the column was measured over time and the results of leachate desorption breakthrough curves [66, 67] are schematically shown in Fig. 10. The effluent concentrations of contaminants for three different flow rates were determined to follow a first-order model as shown in Eq. (95), with the coefficients fitted by the linear regressions given in Table 3 ... 

Fig. 6.1 A breakthrough curve generated by the frontal analysis method [31], The analysis represents a high-volume injection of caffeine through a reversed-phase column, at a concentration representative of the linear region of the binding isotherm. Adapted with permission from Elsevier.

Fig. 6.3 A dissection of the frontal chromatogram [31]. The breakthrough curve is represented by the thick line. The two gray/hatched surfaces on the left side (Ai, A2) represent the mass of compound in the extra- and dead-column volumes. Area A3 represents the mass of the compound adsorbed to the stationary phase. Adapted with permission from Elsevier.

While it is possible for a FAC experiment to require excessive sample in order to equilibrate the column and generate a breakthrough curve, this can be easily... 

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