Laboratory optimization and field demonstration using in-situ reductive dehalogenation of DNAPLS by the use of emulsified zero-valent iron particles

Keywords

Emulsions; Trichloroethylene

Abstract

Research conducted at the University ofCentral Florida demonstrated the feasibility ofusing emulsified iron particles to assist in the dehalogenation ofdense nonaqueous phase liquids (DNAPLs) such as trichloroethylene (TCE). The emulsion consisted ofa surfactant-stabilized, biodegradable oil-in-water emulsion with nanoscale or microscale iron particles contained within the emulsion droplet. It was proven that TCE diffuses through the oil membrane ofthe emulsion droplet where it comes in contact with the surface ofthe iron particle in the interior aqueous phase where dehalogenation takes place. Ethene, the terminal product ofthe dehalogenation reaction, diffused out of the emulsion droplet and was measured using head-space analysis. Chlorinated byproducts (cis-dichloroethene (cis-DCE), trans-dichloroethene (trans-DCE) and vinyl chloride (VC) were only observed in very small concentrations below the quantitation limit ofthe GC. Studies involving the use ofultrasound to break apart the emulsion droplet confirmed that no significant levels ofchlorinated by-products were being trapped within the droplet. In this system, free-phase TCE is degraded at a rate comparable to the degradation ofdissolved-phase TCE by neat iron particles. Due to the hydrophobic nature ofthe DNAPL and the hydrophilic nature ofthe iron particles, iron alone has a very low degradation rate for DNAPL. This study demonstrated the feasibility ofinjecting the emulsified iron system into a soil matrix where it can become immobilized, unmoved by free flowing water. Furthermore, this study proved the 11 emulsion has the ability to envelop the DNAPL within a soil matrix, allowing for degradation to occur, and does not just simply displace the DNAPL in the subsurface. A field demonstration at launch complex 34, Cape Canaveral Air Force Station, FL using a pressure pulse technology injection method proved that the emulsion can be delivered to a subsurface contamination zone. The field study also demonstrated that significant reductions in TCE mass were observed in areas where the emulsion was found.

Notes

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Graduation Date

2003

Advisor

Geiger, Cherie L.

Degree

Master of Science (M.S.)

College

College of Arts and Sciences

Department

Chemistry

Format

PDF

Pages

66 p.

Language

English

Length of Campus-only Access

None

Access Status

Masters Thesis (Open Access)

Identifier

DP0028726

Subjects

Arts and Sciences -- Dissertations, Academic; Dissertations, Academic -- Arts and Sciences

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