Tetrachloroethylene or tetrachloroethene (PCE) is a synthetic chemical often used as a degreaser for metal working and other specific industries. PCE has historically used by the dry-cleaning industry (aka dry-cleaner fluid) as it is highly stable, volatile, and non-flammable. Contamination by PCE in groundwater is common in commercial and industrial areas. Due to partitioning, soil contamination commonly makes up the bulk of PCE mass relative to groundwater.
Applicable Remediation Technologies for Tetrachloroethylene
Physical
SVE: Excellent – As the vapor pressure is greater than 1 mm Hg, soil vapor extraction is an effective process for the remediation of PCE in soil.
Thermal: Excellent – As PCE is already a volatile compound and will work with SVE at typical soil temperatures (see above), thermally enhanced SVE should be used when the PCE is in low permeability material or short remediation time frames are required.
Pump and Treat: Good to Poor – Pump and treat is usually not an effective source remedy for PCE in groundwater, when there is significant non-aqueous mass present (absorbed to soil or non-aqueous phase liquids). There is usually non-aqeous mass present when TCE is detected in groundwater.
Chemical
In Situ Chemical Oxidation (ISCO): Excellent – A variety of oxidant chemistries can successfully mineralize PCE in groundwater and soil.
In Situ Chemical Reduction (ISCR): Excellent – ISCR (for example, zero valent iron or ZVI) has been successful at remediating PCE in groundwater and soil.
Biological
Aerobic: Poor – Generally tetrachloroethylene can only be degraded aerobically via a cometabolic process, requiring the presence of petroleum compounds.
Anaerobic: Excellent – PCE can be anaerobically treated, though often enhancement through the use of a carbon substrate, nutrients, or pH adjusters may be needed to ensure complete transformation of TCE to innocuous end products.
Absorption
Activated Carbon: PCE can adsorb to activated carbon.
Properties
Molecular weight (g/mole): 165.83
Solubility (mg/L): 206
Vapor pressure (mm Hg): 18.5
Henry’s Coefficient (unitless): 0.72
Organic Carbon Partitioning Coefficient (cm3/g): 94.94