132
6 Modelling of Packed Bed Column for the Adsorption …
6.10.2 Adsorbent Regeneration/Reuse
In the first-round studies of adsorption and desorption, no breakthrough curve was
affected. In the second, third and fourth cycles of adsorption and desorption trials, the
weight loss of the beads was 0.0, 5.0 and 11.0%, respectively. The G/CR-CS capabilities in cycles two, three and four of adsorption were 98, 91 and 86%. In the fifth
studies of adsorption/desorption cycles, the adsorption performance significantly
decreased as compared with previous cycles and a 22% weight loss was observed
on the bead mass. It appears that after the fourth cycle the adsorption capacity of
G/CR-CS decreases due to mass loss during many acid remedies. In the fifth cycle,
just about 52% of G/CR-CS capacity was used. The result obtained was shown in
Table 6.4. This reduction in column efficiency may also be due to the chitosan’s
degradability properties, which prevents its non-stop application.
6.10.3 pH Profile
The pH of the initial solution of Cu(II) ions was 4.53 during the first cycle of adsorption studies. However, during the process of adsorption, the pH value was changed
as seen in the opposite form of the breakthrough curves. The pH value of the solution
of Cu (II) ions improved moderately and reached 7.2 before breakthrough. Hence,
there was a rapid shift in the pH value at breakthrough, which correlates to the rapid
increase in concentration of Cu(II) ions. The pH of the outlet solution at the point of
exhaust was the same as the pH of the inlet solution. Medvidovic et al. [30] presented
a similar analysis, with 5 being the initial pH of the metal ion solution which finally
grew to approximately 7.
6.11 Conclusion
The benefit of improving chitosan is not only limited to increasing the distribution
properties but can also reduce the drop in high pressure seen in a packed bed column
with flaky chitosan. A shrinking core mass transfer model was successfully applied
in a packed bed column to project the breakthrough curve for the adsorption of Cu(II)
ions on G/CR-CS at different bed heights. At column operation pH of 5.1, the model
was able to project the breakthrough curve reasonably well. Consequently, from the
experiment carried out from the packed bed desorption, it was observed that the
G/CR-CS expended could be desorbed at a concentration of around three thousand
folds of the initial concentration of Cu(II) ions. Moreover, in the first and second
cycles of adsorption–desorption the mass of the G/CR-CS was unchanged during
desorption studies.
6 Modelling of Packed Bed Column for the Adsorption …
6.10.2 Adsorbent Regeneration/Reuse
In the first-round studies of adsorption and desorption, no breakthrough curve was
affected. In the second, third and fourth cycles of adsorption and desorption trials, the
weight loss of the beads was 0.0, 5.0 and 11.0%, respectively. The G/CR-CS capabilities in cycles two, three and four of adsorption were 98, 91 and 86%. In the fifth
studies of adsorption/desorption cycles, the adsorption performance significantly
decreased as compared with previous cycles and a 22% weight loss was observed
on the bead mass. It appears that after the fourth cycle the adsorption capacity of
G/CR-CS decreases due to mass loss during many acid remedies. In the fifth cycle,
just about 52% of G/CR-CS capacity was used. The result obtained was shown in
Table 6.4. This reduction in column efficiency may also be due to the chitosan’s
degradability properties, which prevents its non-stop application.
6.10.3 pH Profile
The pH of the initial solution of Cu(II) ions was 4.53 during the first cycle of adsorption studies. However, during the process of adsorption, the pH value was changed
as seen in the opposite form of the breakthrough curves. The pH value of the solution
of Cu (II) ions improved moderately and reached 7.2 before breakthrough. Hence,
there was a rapid shift in the pH value at breakthrough, which correlates to the rapid
increase in concentration of Cu(II) ions. The pH of the outlet solution at the point of
exhaust was the same as the pH of the inlet solution. Medvidovic et al. [30] presented
a similar analysis, with 5 being the initial pH of the metal ion solution which finally
grew to approximately 7.
6.11 Conclusion
The benefit of improving chitosan is not only limited to increasing the distribution
properties but can also reduce the drop in high pressure seen in a packed bed column
with flaky chitosan. A shrinking core mass transfer model was successfully applied
in a packed bed column to project the breakthrough curve for the adsorption of Cu(II)
ions on G/CR-CS at different bed heights. At column operation pH of 5.1, the model
was able to project the breakthrough curve reasonably well. Consequently, from the
experiment carried out from the packed bed desorption, it was observed that the
G/CR-CS expended could be desorbed at a concentration of around three thousand
folds of the initial concentration of Cu(II) ions. Moreover, in the first and second
cycles of adsorption–desorption the mass of the G/CR-CS was unchanged during
desorption studies.