Grantee Research Project Results

Final Report: Fiber Optic DNAPL Monitor

EPA Contract Number: 68D02020
Title: Fiber Optic DNAPL Monitor
Investigators: Carter, Michael T.
Small Business: Eltron Research & Development Inc.
EPA Contact: Richards, April
Phase: I
Project Period: April 1, 2002 through September 1, 2002
Project Amount: $69,995
RFA: Small Business Innovation Research (SBIR) - Phase I (2002) RFA Text |  Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , SBIR - Monitoring , Small Business Innovation Research (SBIR)

Description:

This Phase I project was directed at demonstrating the feasibility of a fiber optic sensor for dense nonaqueous-phase liquids (DNAPLs), including chlorinated hydrocarbons such as dichloroethane (DCE) and trichloroethylene (TCE) using solvatochromism as the transduction mechanism. The project's technical objectives included the identification of polymer coatings for the fiber optic sensor, fabrication of sensors with polymer coatings containing the solvatochromic probe, and testing of the sensor response for various DNAPLs in the gas phase and dissolved in water.This Phase I project was directed at demonstrating the feasibility of a fiber optic sensor for dense nonaqueous-phase liquids (DNAPLs), including chlorinated hydrocarbons such as dichloroethane (DCE) and trichloroethylene (TCE) using solvatochromism as the transduction mechanism. The project's technical objectives included the identification of polymer coatings for the fiber optic sensor, fabrication of sensors with polymer coatings containing the solvatochromic probe, and testing of the sensor response for various DNAPLs in the gas phase and dissolved in water.

Summary/Accomplishments (Outputs/Outcomes):

Eltron Research, Inc., found that several polymer films containing Reichardt's dye (RD) were reversibly responsive to changes in the dielectric environment of the induced by uptake of DNAPL into the polymer films. For gas-phase DNAPLs including TCE and DCE, exposure of the film caused reversible shifts in the solvatochromic charge transfer band of the dye consistent with reduction of the average dielectric constant of the film. The solvatochromic band returned to its original position in air. In water, the sensor response was dominated by the polar solvent, although differences were observed between the position of the solvatochromic band in pure water and in DNAPL-saturated water. The use of a hydrophobic barrier layer to prevent the penetration of water into the RD film and facilitate DNAPL penetration was investigated. Evancecent wave and distal tip fiber optic sensor configurations were examined.

Conclusions:

Polymer layers containing RD are sensitive to changes in a dielectric environment and can be used as transducers for the detection of DNAPLs. Distal tip fiber optic sensor configurations are feasible. Care must be taken to prevent water ingress into the polymer-dye layer so that the RD film responds to the DNAPL and not to water.

Supplemental Keywords:

environmental, monitor, dense nonaqueous-phase liquids, DNAPL, trichloroethylene, dichloroethane, Reichardt's dye, fiber optic sensor, SBIR., Health, RFA, Scientific Discipline, PHYSICAL ASPECTS, Water, Waste, Hazardous, Remediation, Health Risk Assessment, Physical Processes, Risk Assessments, Environmental Chemistry, Contaminated Sediments, Hazardous Waste, Ecology and Ecosystems, Environmental Engineering, contaminant transport, sediment treatment, fiber optics, contaminated sediment, human exposure, community support, chemical contaminants, biodegradation, complex mixtures, exposure, sediment transport, technical outreach, web development, urban sediment, human health risk, hazardous substance contamination, DNAPL monitor, technology transfer