| Description |
x, 147 leaves : illustrations ; 28 cm. |
| Summary |
"This thesis describes the sorption and desorption of chlorinated hydrocarbon pesticides by clay minerals under laboratory controlled environmental systems. Particular emphasis was directed toward the investigation of the fundamental adsorption phenomena which occurred in selected pesticide-clay systems. the effects of certain environmental stresses, including pH, temperature and salt (NaCl) concentration of water, on the behavior of sorption and desorption were also studied. Pesticides selected for this study included DDT, dieldrin and heptachlor, and clay minerals employed were kaolinite, montmorillonite and illite. The adsorption rate and equilibrium were evaluated by batch techniques employing completely mixed systems while the effects of the environmental factors on the sorption and desorption were investigated with laboratory controlled aquatic models. Results obtained from this study disclosed that the chlorinated hydrocarbon pesticides were rapidly adsorbed by the experimental clay minerals; in most cases the adsorption equilibria were reached within two hours of reaction. After the pesticides had been adsorbed on the clays, desorption of the pesticides occurred only to a very small extent. It is believed that the uptake of the organochlorine insecticides by the clay minerals is a process of chemical adsorption which involves the formation of certain types of high strength bonding. The pH, temperature and salt (NaCl) concentration of water did not appear to exert significant effects on the sorption and desorption of the chlorinated hydrocarbon pesticides by the clay minerals"--Abstract, leaf ii. |
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