Applications of Equilibrium Thermodynamics - Elements of Environmental Engineering: Thermodynamics and Kinetics - page 162

Further, if γ i wc = γ i w ,wehave

C 1 K ow γ i o K oc =

γ i cw .

(4.80)

It has been observed that most solutes behave nonideally in the octanol phase to
the extent that

o

γ

i is given by (Curtis et al., 1994)

1.2 K 0.16 γ i o =

ow .

(4.81)

Therefore,

log K oc = 1.16 log K ow + log C 2 − log γ i cw , (4.82)

where C 2 = 1.2 C 1 . Hence linear correlations between log K oc and log K ow are pre-

dicted. For example, Curtis et al. (1994) obtained the following linear relationship for
adsorption on the natural organic matter of soils

log K oc = 0.92 log K ow − 0.23. (4.83)

Table 4.12 displays the relationship between log K oc and log K ow . Table 4.13 lists
the available correlations between log K min and log γ i . Note that γ i is related directly

to log K ow (Section 3.4.4.2).

E XAMPLE 4.20 D ETERMINING K sw FROM K ow
A soil from a Superfund site in Baton Rouge, Louisiana, was found to have the following
properties: clay 30%, sand 22%, silt 47%, and organic carbon content 1.13%. Estimate
the soil-water partition constant for 1,2-dichlorobenzene on this soil.

For 1,2-dichlorobenzene, log K ow is 3.39. Hence, log K oc = 0.92 ( 3.39 ) − 0.23 =

2.89. K oc = 774. K sw = K oc φ oc = ( 774 )( 0.0113 ) = 8.7 P/kg.

E XAMPLE 4.21 T IME OF T RAVEL OF A P OLLUTANT IN G ROUNDWATER

The same approach as described above is also used to describe the movement of pollu-
tantsinthesubsurfacegroundwater(Weber,McGinley,andKatz,1991).Sorptionretards
the velocity of pollutant movement in groundwater ( u p ) in relation to the velocity of
the groundwater itself ( u 0 ) . This can be expressed as
u 0

u p = 1 + ρ b

K sw = R F , (4.84)

ε