| Chlorinated Volatile Organic Compounds (CVOCs) are known to pose health and environmental hazards. Granular activated carbon (GAC) treatment has long been recognized as an effective means for the removal of CVOCs from air and water streams. However, there are disadvantages associated with its use, which have lead to research for other adsorbents that could substitute or complement GAC.; This work focused on evaluating various hydrophobic materials as potential adsorbents of four model CVOCs: chloroform, trichloroethylene (TCE), tetrachloroethylene, and carbon tetrachloride. Results showed that Silicalite has a high affinity for these CVOCs, even at ppb concentrations of CVOCs in water. Pure water and CVOC vapor adsorption isotherms of Silicalite, dealuminated Y (DAY), and Centaur® activated carbon samples were generated using the Tapered Element Oscillating Microbalance. Isosteric heats of TCE and water adsorption on Silicalite and DAY were calculated based on adsorption isotherms.; A new hydrophobicity index was defined and compared with other defiinitions available in the literature. It has the benefit of simplicity, use of single compound (water), and does not require the selection of an organic co-adsorbate.; Loading results for TCE from both liquid and vapor phase suggested that the liquid phase did not exist in the pores of Silicalite, while the solution did exist in the pores of Centaur® and DAY samples. This suggestion was supported by the effective density values measured by water and TCE displacement method.; Thermodynamics of confined water were used to explain why liquid water could form in DAY pores, but not inside Silicalite channels. First, an equation of state for water, developed by Truskett et al., was analyzed. Some of the model's predicted results deviate from experimental observations. A new way to determine water parameters was suggested. Further, it was shown that attributing just one hydrogen bond to water molecules can lead to qualitatively wrong results. The hydrogen bonding model was modified accordingly. Then, the equation of state for water-like fluids was derived based on perturbation theory and mean-field approximation. The perturbed state accounts for fluid-fluid, fluid-wall, and hydrogen bonding interactions.; This model was used to analyze the dependence of the density of water inside cylindrical micropores on the density outside the pores, the pore radius, and the affinity of the pore walls for water molecules. For gas-phase adsorption, the model predicts that the density of water inside the pores depends on the fluid-wall interactions. The state of the adsorbed phase varies from the density of vapor outside the pores (for the hard sphere wall) to a bulk liquid-like density (for a hydrophilic sample).; The predicted behavior of confined water in the presence of bulk liquid outside the pores was more interesting. The model predicts that for small pores of hydrophobic materials, the density of fluid inside the pores is much smaller than the bulk liquid density, i.e. vapor like. However, as the radius and/or hydrophility are increased, the fluid density inside the pores approaches the bulk liquid density very rapidly. |
