Environmental Engineering Reference
In-Depth Information
TABLE 11.4
A Comparison of Freundlich Adsorption Parameters
n
and
K
(mg
1−
n
g
−1
L
n
) of
Benzene, Toluene, Phenol, 2-Methylquinoline, Benzofuran, and Benzothiophene
for AC Epibon Y12
×
40, Using Three Different Experimental Methods
Adsorption Isotherm—Freundlich Parameters
Batch Single Compound
Batch Mixture
Column Mixture
Compound
K
N
K
N
K
N
Benzene
21
0.42
30
0.52
33
0.42
Toluene
51
0.38
57
0.33
63
0.38
Phenol
42
0.34
43
0.15
42
0.33
2-Methylquinoline
48 (pH ≪ pK
a
)
156 (pH ≫ pK
a
)
0.20
0.21
163
0.15
100
0.25
Benzofuran
93
0.31
71
0.26
92
0.31
Benzothiophene
149
0.27
136
0.31
142
0.35
Note:
Batch single compound: See results summarized in Table 11.3 (for benzofuran and
2-methylquinoline mean values were used); batch mixture: from a fit of a mixture of the
six compounds specified using the IAS-model; column mixture: from a fit using the LDF-
model [61] of a column experiment with the six compounds specified. Note the different
temperatures used: T(batch) = 20 ± 3°C and T(column) = 12 ± 2°C.
representing a given mass of activated carbon (
m
AC
), were taken and sub-
sequently analyzed. A total of 58 compounds were analyzed and more
than 4000 concentrations were obtained. The fraction
c
i
/
c
0
was calculated
from the individual influent concentration (
c
0
) obtained at time t and port
i
(index
i
= 0-7 represents the influent and port 1-7). The mass of activated
carbon (
m
AC
) for a given port was calculated from the position of the port
and the column dimensions. The boundary condition
c
i
/
c
0
= 0.5 defines
the amount of loaded carbon (
m
L
) for an individual compound. Using a
Fortran-program
m
L
at time
t
was obtained from a plot of
c
i
/
c
0
versus
m
AC
by interpolation below and above
c
i
/
c
0
= 0.5. The linear regression of
m
L
versus
t
leads to the mean adsorption front velocity
v
=
m
L
/
t
(in mg of
loaded activated carbon per hour). The number of data points in linear
regressions performed as described above varied between 2 and 9. The
breakthroughs of phenol and benzene were rapid and only the first two
measurements could be used. However, almost all of the data points were
applicable for strong adsorbing compounds such as anthracene or the cor-
responding N-HET acridine.
A strong linearity was found with a mean correlation coefficient for all
linear regressions performed of R = 0.97. However, errors for strong adsorb-
ing compounds were high, with the worst correlations found for pyrene
(R = 0.58/0.74).
Front velocities of all compounds analyzed for both columns are presented
in Figure 11.10. In addition, the errors of slopes from the plot of m
L
versus t
are included as error bars in Figure 11.10. Front velocities for both columns
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