128
6 Modelling of Packed Bed Column for the Adsorption …
Table 6.2 Swan model
parameters utilized in the
projection of data from the
experiment
Parameters
Values
Mass of wet beads (g)
100
Mean diameter of beads (mm)
1.0
Density ρ (kg/m 3 )
1100
Specific surface area, A, (m 2 /kg)
68.3
Solution pH
5.0
Equilibrium constant
2.5 × 10 −3
Adsorbent capacity (mmol/g)
4.80
n and m
1.0
Molecular diffusion coefficient, D m , for Cu(II)
(m 2 /s) in water
1.43 × 10 −9
External mass transfer coefficient, k, for Cu(II)
(m/s)
4.11 × 10 −6
Reynolds and Schmidt number of 6.17 and shown in Table 6.2. The model was fitted
by adjusting the diffusion coefficient value until such time as a good agreement was
reached, as in Fig. 6.6. Hence, the model is said to provide a rational definition of
the experimental breakthrough curve with diffusion coefficients of 2.82 × 10
−10 ,
2.93 × 10
−10 and 3.12 × 10
−10 m
2 /s at bed heights of 0.21, 0.28 and 0.35 m correspondingly. Since the variance between the experimental and model breakthrough
curve is negligible, it can be assumed that the pH in the column has a significant
influence on adsorption efficiency. The average pH value of 5.1 observed during
column service was used to simulate the column breakthrough and could fairly well
identify the experimental points. At pH 5.2, the model could explain up to 25%
of the column’s actual situation. Consequently, it was also found that the breakthrough period rises from 2.4 to 12 h as the bed height increases from 0.21 to 0.35 m.
This shows that the concentration ratio of the effluent Cu(II) ions increase faster
at a lower bed height than at a higher bed height. To top of this, the bed is filled
faster at a lower bed height than with a higher bed height. Lower bed height implies
lower adsorbent concentrations than for the higher one. As shown in Table 6.3, an
increase in bed height at constant flow rate will increase the Peclet number. Peclet
number, Pe, is expressed as the axial convection rate ratio to the axial dispersal rate.
An increase in bed height and powerful concentration at constant flow rate should
increase Peclet level. The effect of axial dispersion is not important when the Peclet
number is small, and the break point occurs timely, and the breaking point increases
with a higher Peclet number. Therefore, the main variables affecting the kinetics of
Cu(II) ions adsorption on G/CR-CS are said to be the internal and external resistances. Rising bed height elevates the Cu(II) ions solution’s breakthrough time and
residence time in the packed bed. Similar findings were reported by Sulaymon et al.
[2] in the application of granular activated carbon to bind the lead and copper.
6 Modelling of Packed Bed Column for the Adsorption …
Table 6.2 Swan model
parameters utilized in the
projection of data from the
experiment
Parameters
Values
Mass of wet beads (g)
100
Mean diameter of beads (mm)
1.0
Density ρ (kg/m 3 )
1100
Specific surface area, A, (m 2 /kg)
68.3
Solution pH
5.0
Equilibrium constant
2.5 × 10 −3
Adsorbent capacity (mmol/g)
4.80
n and m
1.0
Molecular diffusion coefficient, D m , for Cu(II)
(m 2 /s) in water
1.43 × 10 −9
External mass transfer coefficient, k, for Cu(II)
(m/s)
4.11 × 10 −6
Reynolds and Schmidt number of 6.17 and shown in Table 6.2. The model was fitted
by adjusting the diffusion coefficient value until such time as a good agreement was
reached, as in Fig. 6.6. Hence, the model is said to provide a rational definition of
the experimental breakthrough curve with diffusion coefficients of 2.82 × 10
−10 ,
2.93 × 10
−10 and 3.12 × 10
−10 m
2 /s at bed heights of 0.21, 0.28 and 0.35 m correspondingly. Since the variance between the experimental and model breakthrough
curve is negligible, it can be assumed that the pH in the column has a significant
influence on adsorption efficiency. The average pH value of 5.1 observed during
column service was used to simulate the column breakthrough and could fairly well
identify the experimental points. At pH 5.2, the model could explain up to 25%
of the column’s actual situation. Consequently, it was also found that the breakthrough period rises from 2.4 to 12 h as the bed height increases from 0.21 to 0.35 m.
This shows that the concentration ratio of the effluent Cu(II) ions increase faster
at a lower bed height than at a higher bed height. To top of this, the bed is filled
faster at a lower bed height than with a higher bed height. Lower bed height implies
lower adsorbent concentrations than for the higher one. As shown in Table 6.3, an
increase in bed height at constant flow rate will increase the Peclet number. Peclet
number, Pe, is expressed as the axial convection rate ratio to the axial dispersal rate.
An increase in bed height and powerful concentration at constant flow rate should
increase Peclet level. The effect of axial dispersion is not important when the Peclet
number is small, and the break point occurs timely, and the breaking point increases
with a higher Peclet number. Therefore, the main variables affecting the kinetics of
Cu(II) ions adsorption on G/CR-CS are said to be the internal and external resistances. Rising bed height elevates the Cu(II) ions solution’s breakthrough time and
residence time in the packed bed. Similar findings were reported by Sulaymon et al.
[2] in the application of granular activated carbon to bind the lead and copper.