Environmental Fate and Transport of Solvent-Stabilizer Compounds - Environmental Investigation and Remediation - page 147

TABLE 3.12
Humic Acid/Air Partition Coeffi cients at 15°C

Relative Humidity

< 0.01% 45% 70% 98%

Substance K HA-air (L/kg) K HA-air (L/kg) K HA-air (L/kg) K HA-air (L/kg)

Phenol 797,000 1,770,000 967,000 1,920,000

1,4-Dioxane 4680 12,200 7000 16,900

Nitroethane 2390 3360 3430 3040

Nitromethane 1560 4270 2650 3110

2-Butanone 2400 1730 1340 2440

n -Propyl Acetate 5030 1220 1480 1930

2-Butanone 2400 1730 1340 2440

Source: From Niederer, C., Goss, K.U., and Schwarzenbach, R.P., 2006a, Environmental Science and Technology 40(17):
5368-5373. With permission.
Notes: The K HA-air partition coefi cients are stated as the liters of air containing the given substance per kilogram of humic
acid. Data for 1,4-dioxane are shown in boldface. Calculations are according to Equation 3.39.

Smectite clays have silica and aluminum layers assembled in a 2:1 ratio of silica to aluminum, that
is, -Si·Al·Si·Si·Al·Si-. The lattice structure of smectite clays can expand in response to water and
other agents, including sorption of organic compounds on both external and internal surfaces. Organic
molecules and water can penetrate the layers of the clay-mineral crystal, changing its structure and
swelling properties.
Wu et al. (1994) mixed 1,4-dioxane at concentrations of 0.5, 1, and 3 M [4.4%, 8.8%, and
26.4% (i.e., 264,000 mg/L)] in a suspension of deionized water and sodium-saturated smectite. The
suspension was deposited on a ceramic i lter within a sealed environmental chamber equipped with

TABLE 3.13
Humic Acid/Soil-Vapor Partition Coeffi cients at 98% Relative Humidity

Temperature

5°C 15°C 25°C

Substance K HA-air (L/kg) K HA-air (L/kg) K HA-air (L/kg)

Phenol 2,080,000 990,000 416,000

2-Butanone 2430 708 759

Ethyl acetate 1340 247 —

Tetrahydrofuran 1620 504 —

1,4-Dioxane 15,100 6550 4380

Acetonitrile 2630 1460 978

Nitromethane 2900 1880 1070

Nitroethane 2850 1940 —

Pyridine - 2270 —

Source: From Niederer, C., Goss, K.U., and Schwarzenbach, R.P., 2006a, Environmental Science and Technology 40(17):
5368-5373. With permission.

Notes: The K HA-air partition coefi cients are stated as the liters of soil vapor containing the given substance per kilogram of

humic acid. Data for 1,4-dioxane are shown in boldface.