Document Type
Thesis
Date of Award
5-31-1989
Degree Name
Master of Science in Environmental Engineering - (M.S.)
Department
Civil and Environmental Engineering
First Advisor
Su Ling Cheng
Second Advisor
Paul C. Chan
Third Advisor
Hsin Neng Hsieh
Abstract
The objective of this study was to investigate the removal of contaminants from clay soils by thermal treatment. There were two phases involved in this project. The first was a study of equilibrium adsorption of clay - organics study, and the second was the determination of the thermal desorption characteristics.
Three organics, phenol, chlorophenol, and chlorobenzene and one clay soil, bentonite, were selected for these studies. The first phase, involved the simulation of the isothermal adsorption simulated the process of contaminants being sorbed onto bentonite. Three different isotherm models,viz, Linear isotherm, Freundlich isotherm, and Langmuir isotherm were evaluated with experimental results. Among them, the Freundlich isotherm was found to give the best fit.
The thermal desorption study involved the evaluation of parameters such as, temperature, time, and energy required for levels of desorption in a clay - organic system. A thermogravimetric analyzer (TGA) was connected to a gas chromatograph (GC) by means of an interface unit, consisting of a sampling loop and a six - port valve. This system was also connected to a differential scanning calorimetry (DSC) for determination of desorption enthalpy. A kinetic model was formulated for predicting the energyand time needed for optimum efficiency.
The experimental results indicated that adsorption capacity of clays was a function of hydrophobicity, aromaticity, and polarity of the organics used. Of the three organics used, chlorobenzene, which had the most hydrophobicity and the strongest polarity was the most adsorbed organic with bentonite. The other two, phenol was more readily adsorbed than chlorophenol.
The optimum temperature for desorption was found to occur at a temperature slightly above the boiling point of the organic. In addition, it was found that the removal efficiency of the phenol - bentonite system could exceed 98% if the temperature is kept at 300°C for 18 minutes.
Recommended Citation
Mao, Wen-Ming, "Removal of contaminants from clay soils by thermal desorption" (1989). Theses. 2850.
https://digitalcommons.njit.edu/theses/2850
