Monday, November 5, 2007
92-7

Complexation of Metals by Cyclodextrins in the Presence of Various Co-Ionic and Counter-Ionic Species.

Omar R. Harvey, Water Management and Hydrologic Sciences, Texas A & M University, College Station, TX 77843 and Bruce Herbert, Texas A&M University, Texas A&M University, 3115 Geology & Geophysics, College Station, TX 77843-3115.

Recent developments in remedial technologies, suggests that native cyclodextrins (as well as simple soluble derivatives or insoluble polymers) may be used as sorbents or complexing agents for remediating soils and aqueous systems contaminated by PAHs, BTEX compounds and heavy metals. Little information is available on the effects that various ions may have on the complexation of metals by cyclodextrins, especially at high pH. In this study the effect of both cationic and anionic species on the sequestration of various metals by cyclodextrins under different environmental conditions was investigated. Preliminary results using β-cyclodextrin to complex soluble Al species at pH 10.5 suggested that complexation was enhanced in the presence of SO42- compared to Cl-. Over a 24h equilibration period, approximately 75% of the Al was complexed by β-cyclodextrin in the presence of SO42- compared to 25% in the presence of Cl-. The mechanism involved is unclear and will be investigated. The effect that these and other ions may have on cyclodextrin complexation of environmentally significant metals such as heavy metals will also be investigated.