Grantee Research Project Results
Investigation of Ion Transport and Selectivity Achieved With Crown Ether Fixed-Site Carrier Membranes
EPA Grant Number: U914986Title: Investigation of Ion Transport and Selectivity Achieved With Crown Ether Fixed-Site Carrier Membranes
Investigators: Thunhorst, Kristin L.
Institution: University of Colorado at Boulder
EPA Project Officer: Packard, Benjamin H
Project Period: January 1, 1996 through January 1, 2000
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1996) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Safer Chemicals , Fellowship - Chemical Engineering
Objective:
The objectives of this research project are to: (1) address how ion transport through crown-ether-containing membranes is affected by the membrane and carrier properties; and (2) analyze the role of the structural and material properties.
Approach:
This study has focused on fixed-site carrier membranes-solid
polymeric membranes with crown ether functionalities polymerized into the
polymer backbone. The solid membranes were mounted in a transport cell, and
experiments
with varying aqueous solutions have been conducted. The ion transport of
potassium, sodium, rubidium, and cesium through membranes of varying composition
has been
investigated to date with some single-component and some multicomponent experiments.
The effect of the anion, which accompanies potassium also has been investigated.
In our studies, we have seen that the flux of the potassium cation is affected
by the anion accompanying its transport through the solid membranes, but
in a completely contrary trend to that observed with the liquid membrane systems.
The experiments have been conducted using membranes with 73.1-73.6 percent
VB18C6 and 2.0-2.1 percent hexamethylene diacrylate in the monomer mixture.
Experiments have been completed that investigate the transport (through the
fixed-site membranes) of potassium and sodium ions with the following counter
ions: nitrate, perchlorate, triflate, and chloride. We have seen that the
transport
rate of potassium is greatest when nitrate or chloride is the counter anion
than when perchlorate or triflate salts were employed. This is completely
counter to the observations that have been made with liquid membrane systems
(increasing flux with increasing -GA).
Supplemental Keywords:
fellowship, ion transport, fixed-site carrier membranes, potassium ions, sodium ions, ion selectivity.Progress and Final Reports:
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.