| Popis: |
High purity water can be produced either by ion exchange or through electrodeionization. The latter deionization technology is superior to the former in many aspects, including no chemicals required, environmental friendliness, and easy operation. However, it usually needs the assistance of selective ion exchange membrane, causing a series of problems, such as high cost, difficulty in repairing, and membrane fouling. In this work, a new process called as membrane-free electrodeionization has been proposed and tested for high purity water production. It was operated in a batch countercurrent mode, alternating with a long service step and a short regeneration step. A total of 20 operational cycles were examined. The effluent conductivity was 0.056–0.059 μS/cm only. The Na+ and Ca2 + concentrations, conductivity and pH value of the concentrate, as well as the voltage required were examined systematically during regeneration. The conductivity of the concentrate varied from 217 μS/cm to 150 μS/cm, the average pH value of the concentrate was 7.9, and the average voltage was 730 V. Effective regeneration was achieved, and the resins after repeated regeneration still remained their good efficacy for deionization. |
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