Masters Theses

Date of Award

8-1988

Degree Type

Thesis

Degree Name

Master of Science

Major

Chemistry

Major Professor

Spiro D. Alexandratos

Abstract

Stable metal ion recovery systems were synthesized by incorporating extractant monomers into polymer supports and polymerizing them to form interpenetrating polymer networks. These systems were analyzed in order to determine the factors that optimized stability. Two types of polymer supports were used. A macroreticular styrene bead, with five percent crosslinking, was utilized as a physically analogous control for a macroreticular polypropylene membrane of approximately the same porosity. Two types of extractant monomers were used: a phosphoric acid and a phosphate ester. Diundecenyl phosphate (DUP) was synthesized to yield 46% of the product at 96% purity. The triester, triundecenyl phosphate (TUP), was synthesized by a reverse order Schotten-Baumann reaction and purified by vacuum distillation to yield 70% of the product at 92% purity. DUP and TUP were copolymerized with acrylonitrile (AN) to yield stable IPN extractant systems. Bead stability was analyzed by monitoring phosphorus capacity loss through a series of ethanol elutions. IPN formation was promoted by increased extractant concentration, allylic-AN copolymer formation, at least a one to one ratio of allylic to acrylonitrile bonds, and high initiator concentrations. DUP-TUP-AN IPN resins were found to lose as little as 34% of their capacity after elution with 75% ethanol, compared to a loss of 76% for a comparable PAE control. The same factors that promoted DUP-TUP-AN stability in the polystyrene support were found to be important in the polypropylene membrane support. Membrane stability was enhanced by using a large excess of swelling solvent-extractant containing solution, swelling solution agitation, and the use of a high boiling aromatic swelling solvent containing small amounts of a long chain aliphatic co-solvent. Membranes were analyzed by monitoring the transport of copper metal ions from a pH 4.2 Na2SO4/NaHSO4 feed side to a one molar HCl strip side. Instability was brought about by extractant solubility and hydration. A DUP-TUP-AN IPN membrane was synthesized and went through 29 solution changes, over 34 contact days, with a nine percent loss in its initial permeability, five percent hydration, and a 2.7% loss in its capacity. This was compared to a similar PAE control which lost 71% of its permeability and 55% of its pH drop over seven solution changes.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS