| This dissertation research has three primary objectives. Firstly, this work examines the sorption patterns for clays modified with quaternary ammonium cations with a series of continuous small-to-intermediate-sized alkyl functional groups (methyl, ethyl, propyl and butyl chains) to elucidate the contributions of adsorption and partitioning in nonionic compound uptake. Equilibrium isotherm studies showed one and two carbon-chain amendments supported surface adsorption of four compounds studied: benzene, trichloroethylene, 1,2-dichlorobenzene, and carbon tetrachloride. Three and four carbon-chain amendments showed linear isotherms. A modified Polanyi-Manes equation, the Dubinin-Radushkevich equation, was applied to the adsorptive data and tit the data well relative to a more conventional Langmuir model. The Dubinin-Radushkevich model will potentially allow the prediction of multiple isotherms from one empirically derived characteristic isotherm if the solutes in question have similar chemical structures, i.e. trichloroethylene and carbon tetrachloride.;Secondly, this work studies the effectiveness of two organoclays in the simultaneous sorption of heavy-metal cations (Pb, Hg, Cd, Zn) and benzene. The effect of competition between the distinctly different solutes was quantified and compared between the two clays. As hypothesized, the adsorptive clay, benzyltriethylammonium clay (BTEA), showed decreased uptake of both the heavy metal and benzene, likely due to steric hinderance at the surface of the clay. Also as expected, the partitioning clay, hexadecyltrimethylammonium clay (HDTMA), showed no decrease in benzene uptake. However, the metal uptake onto the partitioning clay was decreased in the presence of benzene. Although there was competition between the solutes on both clays, it was found that both types of clays could simultaneously sorb both metal and nonionic organic compounds, making organoclays a highly effective treatment option for mixed-waste sites.;Lastly, this work investigates the environmental quality of wash/lubricant wastewater generated at Virginia Department of Transportation (VDOT) winter maintenance sites during routine maintenance of the salt-spreader machinery. Soil samples and field measurements both indicate that excess lubricant product is contaminating the soil below the salt-spreader racks. This work investigated organoclays as a treatment method for bulk-phase petroleum removal from oil-water mixtures like those produced during the lubrication of the salt-spreaders. This work studied the sorption capacity of two lubricant products, Lubri Kote from Select Specialty Products and Tool and Chain Lube from Seymour of Sycamore to two commercially available organoclays. EC-199 from Biomin, Inc. and PM-199 from Cetco. The results indicate that organoclay filtration is a viable treatment option for petroleum-based lubricants used at VDOT locations. |
