Multicomponent Equilibrium Thermodynamics - Elements of Environmental Engineering: Thermodynamics and Kinetics - page 96

7.0E-10

6.0E-10

5.0E-10

4.0E-10

3.0E-10

2.0E-10

Calculated

Experimental

1.0E-10

0.0E+10

0 0.1 0.2 0.3 0.4 0.5

C i /mol/L

0.6 0.7 0.8 0.9 1

FIGURE 3.15 Adsorption of n -butanol at the air-water interface.

Equilibrium Aqueous Amount

Concentration ( μ g/L) Adsorbed ( μ g/g)

TCE DCE TCE DCE

1.0E05 100

1.5E05 280

3.0E05 450

3.7E05 600

4.0E05 740

5.2E05 880

3.7E05 100

9.8E05 300

1.4E06 350

2.3E06 700

It is generally true in environmental engineering literature that most data for sparingly
soluble neutral organics is plotted as linear isotherms. The linear isotherm concept is
said to hold for these compounds even up to their saturation solubilities in water. For
the above compounds, the saturation solubilities are 8.4E06 for DCE and 1.3E06 for
TCE. A plot of the amount adsorbed versus the equilibrium solution concentration can
be made for both solutes (Figure 3.16). The linearity is maintained in both cases with
correlation coefficients of 0.9758 and 0.9682 for DCE andTCE, respectively.The linear
adsorption constants are 0.291 and 1.685 L/kg for DCE and TCE, respectively. Since
TCE is less soluble and more hydrophobic (cf. the discussion of hydrophobicity in the