Page 37 - Partition & Adsorption of Organic Contaminants in Environmental Systems

28 FUNDAMENTALS OF THE SOLUTION THEORY

TABLE 2.2. Solubility Parameters for Selected Compounds at Room Temperature
3 0.5
3 0.5
Compound d (cal/cm ) Compound d (cal/cm )
Aliphatic hydrocarbons ethylene dibromide 9.7
n-pentane 7.1 trichloroethylene 9.2
n-hexane 7.3 tetrachloroethylene 9.3
n-heptane 7.4 chlorobenzene 9.5
n-octane 7.5 bromobenzene 9.9
cyclopentane 8.1 o-dichlorobenzene 10.0
cyclohexane 8.2
Alcohols
Aromatic hydrocarbons methanol 14.5
benzene 9.2 ethanol 12.7
toluene 8.9 n-propanol 11.9
ethylbenzene 8.8 n-butanol 11.4
o-xylene 9.0 benzyl alcohol 12.1
m-xylene 8.8 cyclohexanol 11.4
p-xylene 8.8 n-octanol 10.3
n-propylbenzene 8.6 ethylene glycol 14.6
styrene 9.3 glycerol 16.5
naphthalene 9.9 Ketones
phenanthrene 9.8 acetone 9.9
anthracene 9.9
methyl ethyl ketone 9.3
Halogenated carbons acetophenone 10.6
methylene dichloride 9.7
Nitrogen compounds
ethylene dichloride 9.8
aniline 10.3
chloroform 9.3
pyridine 10.7
carbon tetrachloride 8.6
quinoline 10.8
1,1,1-trichloroethane 8.5
Source: Data from compilations of Hildebrand et al. (1970) and Barton (1975).

3
energy/volume and is commonly expressed in cal/cm . DE int is related to the
molar enthalpy of the liquid, which is numerically equal to the molar heat of
evaporation of the liquid (DH evap ), such that

DE int = DH evap - RT (2.40)

where R is the gas constant and T is the system temperature. Since at room
temperature the RT term is usually small relative to DH evap , except for liquids
of very small molecular sizes, DE int is approximately equal to DH evap . In theory,
for any two liquids to be miscible or sufficiently compatible with each other
in forming a solution, their CEDs must be close to each other. Conversely, if
the two liquids differ markedly in their CEDs, the solution as formed will then
deviate considerably from being ideal (or athermal).