Date of Award

Fall 1995

Document Type

Thesis

Degree Name

Master of Science in Environmental Science - (M.S.)

Department

Chemical Engineering, Chemistry and Environmental Science

First Advisor

Jay N. Meegoda

Second Advisor

Richard B. Trattner

Third Advisor

Wenpin D. Ho

Abstract

Soil washing is an ex-situ process employing chemical and physical extraction and separation techniques to remove a broad range of organic, inorganic, and radioactive contaminants from soils. This research investigates the enhanced soil washing of a high level Polycyclic Aromatic Hydrocarbons (PAHs) contaminated coal tar soil by the application of ultrasound energy coupled with surfactant (soap) emulsions and attempts to optimize pollutant removal from contaminated soils. The non-ionic surfactant, octyl-phenyl-ethoxylate, was used as the surfactant.

Using bench-scale experiments, the magnitude of the ultrasonic enhancement was evaluated by changing the process parameters, such as ultrasonic power density, Dwell (extractor residence time), surfactant concentration, solvent ratio (liquid/soil w/w ratio), pH, and temperature. Experimental results show that the ultrasonic power density was the main contributing factor for the removal of PAHs. In general, the enhancement of removal efficiency due to ultrasound reached up to 40% to 60% when compared with that without ultrasound. The optimum condition with ultrasound was obtained at a solvent ratio of 25 with 750 Watts power density, 30 minutes dwell time, and 1% concentration of surfactant solution. The removal efficiency can be further improved by increasing the pH of the surfactant solution.

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