| Figure 15 shows the effect of CO 2 flow rate on the rate of desorption. It is clear that increased SCF flow increased both the rate of desorption and the maximum amount of caprolactam desorbed.

Figure 15: The effect of CO 2 flow rate on
desorption of caprolactam /GAC-F400 system at
250 bars and 40ºC.
At higher flows (> 3 L/min) the desorption rate curves became closer, as they showed a balance between two contradicting effects: higher solvent amounts in a unit time would enhance desorption, and increased solvent flow rate would reduce film mass transfer limitations, which increased desorption rate on the one hand. Whereas reduced residence time would naturally reduce the mass desorbed. The net effect is enhanced desorption rate. |