Date of Award

1996

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Civil and Environmental Engineering

First Advisor

Yalcin B. Acar

Abstract

An assessment of the feasibility of micellar electrokinetic (EK) remediation of TNT from soils is presented. Batch solubilization tests and bench scale EK tests were conducted to select the best candidate surfactant and to evaluate the efficiency of removal of TNT from a real world soil. From batch tests, it was found that SDS gave the best desorption results among a group of candidate surfactants, which includes DOWFAX 8390 (anionic), Tween 80 and Brij 35 (nonionic) and CTAB and CTAC (cationic). Unenhanced and surfactant enhanced EK tests was unable to move substantial amounts of TNT across the specimen to the electrodes. TNT concentrations reduced significantly in the soil sample at sections closest to the cathode after EK processing. This was postulated to be due to transformation of TNT to TNT anions (Jackson-Meisenheimer anions or the Janovsky's complex). EK tests with neutralization at the electrodes achieved both characteristics, i.e. improvement of electroosmotic flow and preventing TNT transformation to TNT anions. Changing the process parameters, such as improving electroosmotic flow, maintaining a constant pH across the medium and extending processing period also did not improve the process in terms of efficiency is evaluated by pulsing the process. The pulse type processing also did not improve electroosmotic flow nor it improved TNT transport for 5% Tween 80 solution. Electroosmotic flow significantly increased in pulse type loading with 20% methanol solution. From the limited data obtained, it is demonstrated that a pulse type loading may be a more efficient technique to drive pore fluid into the soil compared to a continuous current method. There is also evidence of improved transport of TNT in the soil specimen in this type of system. This study provides further evidence to demonstrate that nonpolar species such as TNT cannot be transported from soils by electroosmosis. The attempt to desorb, solubilize and polarize TNT by the formation of micelles with SDS, although successful in batch extraction through vigorous shaking, becomes ineffective in extracting TNT in bench scale EK experiments.

ISBN

9780591035452

Pages

162

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