Date of Award

1986

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Civil and Environmental Engineering

Abstract

The suitability of the electro-odo-cell (EOC) for detection of organic chemical contaminants in ambient air and soil strata was investigated under laboratory conditions. The existing concept of the EOC was modified to incorporate the system into a state of the art subsurface soil investigation probe (electric cone penetrometer). Partial theoretical support for EOC operation was developed. The state of the art in reactive solute transport in soils was reviewed. From this review inferences were made about time of travel of a permeant in soil samples, which was consequently compared with time of initial response of the laboratory prototype cone penetrometer with EOC (C/EOC). Combinations of different membranes and contaminants were tested in ambient conditions. EOC responses to variations in temperature, pressure, cell-chamber geometry, membrane pore size, membrane composition, external ionic field, salt solutions, contaminant concentration, contaminant type and membrane solubility were investigated. Problems associated with simulated C/EOC operation under saturated conditions were addressed. The results of adsorption/desorption were presented as plots of changes in C/EOC output voltage vs. time. Statistical analyses of the results provided good correlations between the output voltage and concentration, vapor pressure, surface tension, dipole moment of the organic permeant, solubility factor of membrane, and hydraulic conductivity of the soil. Based on the findings of this study, the following conclusions were reached: (1) EOC and C/EOC are capable of odorous contaminant detection in both gaseous and aqueous conditions. (2) Theories based on chemisorption are most suitable in explaining characteristic operation of the C/EOC in detection of contaminants. (3) Variations in temperature or the environment and pore size of the membrane have minimal effects on EOC output. (4) Each chemical and membrane combination has a unique output signal signature which is different from any other. (5) C/EOC response to sudden external pressure and application of ionic field is characteristically different from contaminant detection response. (6) It is envisioned that C/EOC can be used for either continuous or intermittent (multiple) contaminant monitoring in saturated porous media. (8) C/EOC has capabilities for selective detection of different contaminants and different concentrations. This is an exploratory pilot study, recommendations for future research on the topic are also given.

Pages

276

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