Elution/regeneration

Resin sedimented Resin expanded Feed loading and washing Fixed-bed elution Regeneration... 

Since properties of both phosphate and arsenate are very similar each other, the adsorption of phosphate was examined prior to the adsorption of arsenic species. Here, the feeding solution in the adsorption operation was 1 mM phosphate solution of pH3. Table 1 summarizes detailed experimental conditions and column performances during repeated adsorption-elution-regeneration cycles. Since supplied volumes of the feed are not constant (101 - 193 BV), it is not easy to judge the efficiency of the adsorption from total uptake of phosphate. Thus, removal of phosphate until 100 BV is listed at the last column of Table 1 as an index of the column performances. 

Table 1. Conditions and results of adsorption-elution-regeneration cycles for removal of phosphate.

In runs from 2-1 to 2-4, the adsorption of phosphate was carried out by supplying the feeding solutions at SV 10 h 1. Leakage of phosphate from the column up to 100 BV of the feed is markedly depressed by repeating the adsorption-elution-regeneration cycle of the method (ii). In the runs from 2-2 to 2-4, the uptake until 100 BV of the feed is almost quantitative, and then the flow rate of the feed increased to SV 20 h1. Even at the higher flow rate of SV 20 h 1 (runs from 3-1 to 3-7), the column took up phosphate almost quantitatively up to 100 bed volumes of the feed. 

Fig. 7.5. Tandem reactor concept for single-stage, high-conversion Claus process with integrated elutive regeneration.

It is instructive to compare the example of the seemingly more feasible Claus process with the less tractable direct HCN synthesis. The major difference lies in the much poorer selectivity of both catalyst and adsorbents at the higher temperatures (400 °C rather than 250 °C) in the latter case, which would seem to indicate that adsorptive reactors function better at lower temperatures. The ability to use a process gas stream for elutive regeneration and to overcome problems due to distortive reactant adsorbent on the catalyst using the partial de-integration described in Section 7.5.1 are further points favoring the use of adsorptive reactors in the first instance. 

Unlike carbon however, the polymer adsorbents can be eluted (regenerated) with polar solvents such as methanol, propanone (acetone), electrolytes, or even water. 

The elution/regeneration step, which includes backwashing, eluting, and rinsing the resin, might take up to four hours. Therefore, enough resin must be supplied to take up the lysine-HCl presented during that time. The resin requirement for the commercial scaleup operation would be ... 

Loading times and elution-regeneration times should be approximately equal. 

Elutant (Regenerant) Cation-exchange capacity (meq/lOOg zeolite) change in CEC from as rec d state(%)... 

The use of powders is generally in a belch phase, The solution to be treated is mixed with en appropriate quantity of the activated-carben powder, agitated forless then 1 h, and then separated by settling or filtration. The used catbon may be discarded or "eluted" (regenerated) fur further use. The use of particulate forms in liquid treating employs fixed beds through which the solution to be trained is passed, When the beds become saturated, they can be revivified by gas oxidation or solvent extraction. 

Step 1 Columnl is eluted, regenerated, and finally equilibrated, while columns... 

Step 3 As shown in Figure 5.27, the process scheme is changed again. Now column 2 is eluted, regenerated, and equilibrated while columns 3, 4, and 1 are loaded. 

After elution, regenerate the columns with 2 mL of the regeneration buffer. Then wash the columns with 2 mL of distilled water, equilibrate with the equilibration buffer (2 mL), and store at 0-4°C in 20% (v/v) ethanol. 

Equilibration Sample application Washing step Elution Regeneration... 

Figure 7 Schemes of conventional four-step (left) and dual-temperature two-step (right) column operational cycles. Simplest cases are presented. If two dissolved substances are separated with the dual-temperature technique, the stages could be assigned to i) sorption of first substance with desorption of second substance ii) sorption of second substance with desorption of first substance. As one can see, the dual-temperature scheme does not involve an addition of an external chemical that is inevitable in the conventional scheme (elution/regeneration step).

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