The effects of cold temperature on copper ion exchange by natural zeolite for use in a permeable reactive barrier in Antarctica

Permeable reactive barriers (PRBs) are an in-situ passive treatment technology that removes dissolved contaminants from polluted waters through the subsurface emplacement of reactive materials such as natural zeolite. While significant work has been achieved using PRBs in temperate climates, adaptations to existing PRB technology and reactive material characteristics will be necessary for the successful treatment of heavy metal contaminated waters in cold regions. This study investigates the effects of cold temperature on the ion exchange equilibria of copper with clinoptilolite, a common natural zeolite, in natural and pretreated sodium forms. Batch tests were conducted at 22 and 2degreesC in both simple binary systems and more complex multi-component systems. Results show that cold temperatures decrease copper uptake by clinoptilolite and appear to slow reaction kinetics. The ion exchange of copper in slightly saline waters is decreased at both 22 and 2degreesC compared to uptake in simple binary systems. These results will have significant implications on cold region barrier design. (C) 2003 Elsevier Science B.V. All rights reserved.