Citation:

Werth, C. J. AND M. Reinhard. EFFECTS OF TEMPERATURE ON TRICHLOROETHYLENE DESORPTION FROM SILICA GEL AND NATURAL SEDIMENTS. 1. ISOTHERMS. (R822626). ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 31(3):689-696, (1997).

Description:

Aqueous phase isotherms were calculated from vapor phase desorption isotherms
measured at 15, 30, and 60 C for
trichloroethylene on a silica gel, an aquifer sediment, a soil, a sand fraction,
and a clay and silt fraction, all at 100% relative humidity. Isosteric heats of
adsorption (Q_st(q)) were calculated as a function of
the sorbed concentration, q, and examined with respect to the following
mecha nisms: adsorption on water wet mineral surfaces, sorption in amorphous
organic matter (AOM), and adsorption in hydrophobic micropores. Silica gel, sand
fraction, and clay and silt fraction 60 C
isotherms are characterized by a Freundlich region and a region at very low
concentrations where isotherm points deviate from log-log linear behavior. The
latter is designated the non-Freundlich region. For the silica gel, values of
Q_st(q) (9.5-45 kJ/mol) in both regions are consistent
with adsorption in hydrophobic micropores. For the natural solids, values of
Q_st(q) in the Freundlich regions are less than or equal
to zero and are consistent with sorption on water wet mineral surfaces and in
AOM. In the non-Freundlich regions, diverging different temperature isotherms
with decreasing q and a Q_st(q) value of 34
kJ/mol for the clay and silt fraction suggest that adsorption is occurring in
hydrophobic micropores. The General Adsorption Isotherm is used to capture this
adsorption heterogeneity.

Record Details:

Record Type:DOCUMENT( JOURNAL/ PEER REVIEWED JOURNAL)

Product Published Date:01/01/1997

Record Last Revised:12/22/2005

Record ID: 66647

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Document IDs:

EPA Number :R822626