Date of Award

1992

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Marty Tittlebaum

Abstract

The effects of organoclay adsorption on the leaching performance of solidified organic wastes was researched. Adsorption isotherms were developed for the adsorption of 1,2-dichlorobenzene (DCB), nitrobenzene (NB), and phenol by five different organoclays. Simulated liquid wastes containing DCB, NB, and phenol were solidified utilizing various combinations of Type I Portland cement and the five organoclays. The ratio of cement/clay utilized in each solidification matrix varied from 3/2 to 13/2. Linear and Langmuir adsorption isotherm models were utilized to predict the leaching performance of samples cured for 7, 28, and 90 days. The ratio of the actual leachate concentrations compared to the concentrations predicted by the Linear and Langmuir models steadily decreased with increasing cement/clay ratios due to organoclay encapsulation. The leachability of the DCB, NB, and phenol from the organoclay solidification samples was tested utilizing various water contents, curing periods, and concentrations of organic waste solidified. Variations in water content did not affect sample performance. The concentration of organic waste solidified did not affect the actual/model predicted leachate results for the samples. The leachability of the samples did decrease with increasing curing time. Also, two different mixing techniques were utilized. Comparison of these methods determined that the preblending of organoclay with the different wastes prior to cement addition did not enhance leachability performance. A model was developed to predict the leachability performance of organic wastes solidified utilizing organoclays. The model was based on the results of the DCB and NB samples and was limited to predictions for nonionic organic compounds, since the adsorption of the ionic phenol onto the organoclays was affected by the pH and Ca(OH)$\sb2$ concentration of the solidified samples. The model predicts the slope of Linear adsorption isotherms for various organic-organoclay combinations from the organoclay's % organic matter content and the organic's Kow value. This adsorption isotherm slope is utilized to predict solidification sample leachability performance by incorporating a encapsulation correction factor developed to account for the decrease in actual leachate results/Linear model predicted values with increasing cement/clay ratios experienced in the study.

Pages

332

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