Science Inventory

PROPERTY CHANGES IN AQUEOUS SOLUTIONS DUE TO SURFACTANT TREATMENT OF PCE: IMPLICATIONS TO GEOPHYSICAL MEASUREMENTS

Citation:

WERKEMA, D. D. PROPERTY CHANGES IN AQUEOUS SOLUTIONS DUE TO SURFACTANT TREATMENT OF PCE: IMPLICATIONS TO GEOPHYSICAL MEASUREMENTS. Presented at American Geophysical Union Fall 2007 Meeting, San Francisco, CA, December 10 - 14, 2007.

Impact/Purpose:

Land Preservation and Restoration - by providing improved scientific knowledge and developing and applying more cost effective tools, models and methods to inform decisions on land restoration.

Description:

Select physicochemical properties of aqueous solutions composed of surfactants, dye, and

perchloroethylene (PCE) were evaluated through a response surface quadratic design

model of experiment. Nine surfactants, which are conventionally used in the

remediation of PCE, were evaluated with varying concentrations of PCE and indicator

dyes in aqueous solutions. Two hundred forty experiments were performed using PCE as

a numerical factor (coded A) from 0 to 200 parts per million (ppm), dye type (coded B)

as a 3-level categorical factor, and surfactant type (coded C) as a 10-level categorical

factor. Five responses were measured: temperature (oC), pH, conductivity (µS/cm),

dissolved oxygen (DO, mg/L), and density (g/mL). Diagnostics proved a normally

distributed predictable response for all measured responses except pH. The Box-Cox plot

for transforms recommended a power transform for the conductivity response with

lambda (ë) = 0.50, and for the DO response, ë=2.2. The overall mean of the temperature

response proved to be a better predictor than the linear model. The conductivity response

is best fitted with a linear model using significant coded terms B and C. Both DO and

density also showed a linear model with coded terms A, B, and C for DO; and terms A

and C for density. Some of the surfactant treatments of PCE significantly alter the

conductivity, DO, and density of the aqueous solution. However, the magnitude of the

density response is so small that it does not exceed the instrument tolerance. Results for

the conductivity and DO responses provide predictive models for the surfactant treatment

of PCE and may be useful in determining the potential for geophysically monitoring

surfactant enhanced aquifer remediation (SEAR) of PCE. As the aqueous

physicochemical properties change due to surfactant remediation efforts, so will the

properties of the subsurface pore water which are influential factors in geophysical

measurements. Geoelectrical methods are potentially the best suited to measure SEAR

alterations in the subsurface because the conductivity of the pore fluid has the largest

relative change. This research has provided predictive models for alterations in the

physicochemical properties of the pore fluid to SEAR of PCE. Future investigations

should address the contribution of the solid matrix in the subsurface and the solid-fluid

interaction during SEAR of PCE contamination.

Record Details:

Record Type: DOCUMENT (PRESENTATION/ABSTRACT)
Product Published Date: 12/14/2007
Record Last Revised: 07/02/2008
OMB Category: Other
Record ID: 182463

Organization:

U.S. ENVIRONMENTAL PROTECTION AGENCY

OFFICE OF RESEARCH AND DEVELOPMENT

NATIONAL EXPOSURE RESEARCH LABORATORY

ENVIRONMENTAL SCIENCES DIVISION

CHARACTERIZATION & MONITORING BRANCH