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Scale Formation by Electrode Reactions in Capacitive Deionization and its Effects on Desalination Performance

축전식 탈염에서 전극반응에 의한 스케일 생성과 탈염성능에 미치는 영향

  • Received : 2015.12.24
  • Accepted : 2016.01.07
  • Published : 2016.02.10

Abstract

The effects of scale formation of hardness material caused by electrode reactions on the desalination performance of the membrane capacitive deionization (MCDI) were investigated. During the repeated adsorption and desorption process for the influent containing $Ca^{2+}$ ion, changes in effluent concentration and cell potential with respect to the number of adsorption were analyzed. It was found that $OH^-$ generation at the cathode was initiated at about 0.8 V or more of cell potential. In addition, the scale of $Ca(OH)_2$ was formed on the surface of cathode carbon electrode by combining adsorbed $Ca^{2+}$ ions and $OH^-$ ions generated from electrode reaction. As the scale was forming, the electrical resistance of carbon electrode was increasing, which resulted in the decrease of the adsorption amount. In the case of the operation at 1.5 V cell potential, the adsorption was reduced to 58% of the initial adsorption amount due to the scale formation.

Keywords

capacitive deionization;hardness materials;scale formation;electrode reaction;cell potential

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Acknowledgement

Grant : 다가 양이온 선택성 탄소전극을 이용한 경도 및 중금속 이온 제거 기술 개발