| Research Abstract |
Pollution of waters by dioxins, halomethanes, environmental hormones, and other organic pollutants is a serious concern. Generally organic molecules have low solubility to water and their environmental concentrations are low. However, even trace amounts of organic pollutants show strong toxicity and efficient concentration and collection are necessary for the detection and removal of organic pollutants from waters. Recently, nanospaces of porous compounds have been shown to provide very active, unusual fields for chemical reactions, which is ascribed to the overlap of surface potentials in nanospaces. Further, in this investigation the idea is proposed that when organic pollutant molecules are incorporated into reactive nanospaces, the molecules that are closely adjacent show attractive interactions owing to hydrogen bonds and van der Waals forces, leading to the enhancement of incorporation. As nanoporous compounds, layered metal oxides are considered promising because of large ion ex
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change capacities. The oxide phase of such compounds has charges since the positive charge due to metal ions does not match the negative charge due to oxide ions, and the layer charges are counter balanced by interlayer ions. Tetratitanate, birnessite, and ferrite were chosen as layered oxides with cations in the interlayer, and hydrotalcite with anions in the interlayer. The conditions for preparing these compounds were established. As model organic pollutants, alkilammonium with cationic functional groups and adenosinetriphosphate (ATP) with anionic functional groups were chosen, the behavior of incorporation of these organic molecules into the layered metal oxides was studied, and the properties of the reaction products were examined. The large organic molecules achieved full loading in the layered oxides, indicating the high reactivity of nanospaces and the enhancement of incorporation by attractive interactions between incorporated molecules as postulated. The interlayer distances increased corresponding to the molecular heights, suggesting that the incorporated molecules are standing up vertical to the interlayer planes. After small interlayer ions are exchanged with large organic molecules, the layer structure would be sustained by attractive interactions between the large uncharged parts of organic molecules aligned in the interlayer, as the charged functional groups do not contact the two opposing surfaces of an interlayer at the same time. Less
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