63
ratios can be calculated and is presented in Table 5-8. The
study shows phenol suffered the greatest loss of adsorption
capacity when mixed with other phenolic compounds, and
indicates that the loss of adsorption capacity was
predominantly caused by competitive adsorption effects.
Table 5-8. Ratios of Freundlich sorption coefficients for
phenolic compounds in single and multiple
compound systems.
Ratio of KFA: Soil Soil+sludge organic carbon
Phenol 3.05 2.88 2.66
2,4-DCP 1.22 1.47 1.66
PCP 1.51 1.42 1.38
In general, Freundlich sorption coefficients for
phenolic compounds increase as the level of chlorination
increases. The less-than-unity values of the Freundlich
exponent, b, indicate the adsorption was not linear, and
higher concentrations resulted in a proportionately less
amount of adsorption. These values of the Freundlich
exponent are in good agreement with the ones reported by
Boyd (1982) (b=0.79 for phenol and b=0.67 for 2,4-DCP),
Lagas (1988) (b=0.86 for PCP), and Laquer and Manahan (1987)
(b=0.65 for phenol).
The calculated K values (Table 5-4 and Table 5-7) are
oc
closer to those predicted by Equation (3-5), which are 2.99
for phenol, 4.03 for 2,4-DCP and 5.86 for PCP. A least
squares linear regression reveals a good correlation between
the log of water solubility (in umole/l) and log of Ko
oc