Wafer Chemistry and Properties for Ion Removal by Wafer Enhanced Electrodeionization

Electrodeionization is a widely used technology to produce ultrapure water for various applications such as cooling towers, water reclamation for micro-fabrication, and pharmaceuticals. Wafer Enhanced- Electrodeionization (WE-EDI) is a technology which immobilizes resins into wafers allowing for a significant expansion in applications due to a decrease in internal and external channeling and leakage. Although WE-EDI allows for a wide variety of applications in low concentration and selective ion removal, there have been few studies on the effects of various processing variables on WE-EDI performance. This paper investigates the effects of different variables in wafer performance including porosity, capacity, permeability, and ion exchange bead type. Experimental data and predictive modeling shows that thickness and capacity have little effect on the ability of the wafer to enhance cation transport while the ratio of anion exchange to cation exchange resin, the amount of polymer used to bind the resins, and selectivity of the resin beads have a much greater effect. From the experimental and modeling results, it is recommended that the bead chemistry, especially the equilibrium constant K, should be the main consideration for specific ion removal applications.