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