Masters Theses

Date of Award

5-2000

Degree Type

Thesis

Degree Name

Master of Science

Major

Chemistry

Major Professor

Spiro D. Alexandratos

Committee Members

Doug Gilman

Abstract

Binding constants were calculated for a novel class of ketophosphonate coordinating resins and their interactions with Eu (III) in 1 N HNO3. These resins include α-ketophosphonic acid, β-ketophosphonic acid, γ-ketophosphonic acid and the parent phosphonic acid resin. Calculated binding constants indicate that as the length of the carbon spacer between the carbonyl and phosphoryl moieties is increased, the binding strength decreases. This is due to unstable ring formation upon chelation. The phosphonic acid resin gave results similar to those of the γ-ketophosphonate resin even though a ring is not formed upon complexation. This lack of ring formation is due to the absence of the carbonyl group.

Another aspect of the work involves studies with a novel class of quaternary ammonium resins. These resins possess quaternized trimethyl, triethyl, tributyl, and trihexyl groups. A bifunctional resin was also studied which utilized both quaternized trihexyl and triethyl groups. Contact studies were carried out with pertechnetate, perrhenate, iodide, nitrate, bromide, selenate and sulfate in various chloride and nitrate background matrices. Interactions with the monovalent anions showed that the resins with increased alkyl chain length favored ion exchange with the larger anions. This is due to the soft-soft interaction between the ligand and anion. Interactions with divalent anions showed a reversed trend having the trimethyl resin exchanging more than the trihexyl resin. This is due to the hard ligand, hard anion interaction. Uptake for the divalent anions was found to be low regardless of the resin used, since two active sites are needed for exchange rather than just one with the monovalent anions.

Previous studies conducted with these anion exchange resins showed that as the alkyl chain length within the resin is increased, the rate of exchange decreases. This was believed to be due to lack of hydration of the active site due to the increased hydrophilicity as the alkyl chain length is increased. Thermogravimetric analysis of the resins indicated that as the alkyl chain length is increased, the amount of water associated with the site is reduced. A correlation between exchange capacity and amount of water associated with the ligand was found. The amount of water associated with the active site was also found to change as the degree of functionalization and counter-ion is varied.

Even though these results prove our original hypothesis of active site hydration, kinetic studies in high ionic strength solutions showed that each of the resins, regardless of alkyl chain length, exhibited fast kinetics. This is believed to be due to the increased concentration of co-ion within the pores and their ability to help facilitate movement of the exchanging ion within the pores.

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