| 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. The wafer is a mixture of cation exchange resins, anion exchange resins, sugar, and polyethylene. This mixture is bonded together at 237 F and 10,000 psi for 90 minutes and air cooled for 15 minutes. Polyethylene helps to bind the ion exchange resins together. The sugar creates porosity of the wafer by leaving a void structure after being removed. This thesis investigates the effects of different components on wafer performance. It also studies ion selective removal from multi-component systems. The results show that polyethylene has a bigger impact on the wafer's porosity, capacity, and permeability than sugar does. The predictive model and experimental results suggest the ratio of cation to anion exchange in the resin have some impact in single ion removal rates as well as the selectivity in multi-ion removal. However, when the wafer thickness varies from ∼1 to ∼2mm experimentally and 0.05 to 5 mm theoretically, there is no difference in the ion removal rate for a single ion system or for the selectivity for multi-component systems. The results also show the effects of polyethylene and ion exchange resin capacities on single ion removal rate. In order to optimize ion selective removal, the model suggests that thin wafers with a high ion exchange capacity and a low cation to anion exchange resin ratios should be used. |
