Electrically switched ion exchange (ESIX) is a separation technology being
developed at Pacific Northwest National Laboratory as an alternative to con
ventional ion exchange for removing metal ions from wastewater. In ESIX, wh
ich combines ion exchange and electrochemistry, ion uptake and elution can
be controlled directly by modulating the potential of an ion exchange film
that has been electrochemically deposited onto an electrode. This paper pre
sents the results of experiments on high surface area electrodes and the de
velopment of a flow system for cesium ion separation. Bench-scale flow syst
em studies showed no change in capacity or performance of the ESIX films at
a flow rate up to 113 bed volumes/h (BV/h), the maximum flow rate tested,
and breakthrough curves supported once-through waste processing. A comparis
on of results for a stacked five-electrode cell versus a single-electrode c
ell showed enhanced breakthrough performance. In the stacked configuration,
breakthrough began at approximately 120 BV for a feed containing 0.2 ppm c
esium at a flow rate of 13 BV/h. A case study for the KE Basin (a spent nuc
lear fuel storage basin) on the Hanford Site demonstrated that KE Basin was
tewater could be processed continuously with minimal waste generation, redu
ced disposal costs, and lower capital expenditures. (C) 2001 Elsevier Scien
ce B.V. All rights reserved.