Applied Chemistry for Engineering (공업화학)

The Korean Society of Industrial and Engineering Chemistry (한국공업화학회)
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Effect of Current Density and Electroosmotic Phenomena on the Desalination Performance of the Electrodialysis Process

전류밀도와 전기삼투 현상이 전기투석 공정의 탈염성능에 미치는 영향

  • Eun-Seo Cheon (Department of Chemical Engineering, Kongju National University) ;
  • Jae-Hwan Choi (Department of Chemical Engineering, Kongju National University)
  • 천은서 (공주대학교 화학공학부) ;
  • 최재환 (공주대학교 화학공학부)
  • Received : 2023.03.29
  • Accepted : 2023.04.25
  • Published : 2023.06.10
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Abstract

In this study, we analyzed the effects of current density and electroosmotic phenomena on the desalination performance of electrodialysis (ED). We conducted ED experiments under constant voltage conditions, changing the concentration of the concentrate solution from 10 to 200 g/L. During the ED operation, we measured the current density and charge supplied to the stack, the concentration of the diluted and concentrated solutions, and the amount of water transported by electroosmosis to analyze desalination performance. As the concentration of the concentrated solution increased, the selectivity of the ion exchange membrane decreased, resulting in a decrease in current efficiency. Moreover, the current efficiency was found to be influenced by the current density supplied. When the current density exceeded 15 mA/cm2, back diffusion of ions was suppressed, leading to an increase in current efficiency. We also investigated the specific water transport by electroosmosis during the ED operation. We found that the amount of water transported increased proportionally to the concentration ratio of the concentrated and diluted solutions. When the concentration ratio exceeded 100, the specific water transport rapidly increased due to osmotic pressure, making it challenging to obtain a concentrated solution greater than 200 g/L.

이 연구에서는 전류밀도와 전기삼투 현상이 전기투석(electrodialysis, ED)의 탈염성능에 미치는 영향을 분석하였다. 농축액의 농도를 10~200 g/L로 변화시키면서 정전압 조건에서 ED 실험을 진행하였다. ED 운전과정에서 스택에 공급되는 전류밀도와 전하량, 희석액과 농축액의 농도, 그리고 전기삼투에 의한 물 이동량을 측정하여 탈염성능을 분석하였다. 농축액의 농도가 증가함에 따라 이온교환막의 선택성이 감소하여 전류효율이 감소하였다. 또한 전류효율은 스택에 공급되는 전류밀도에 영향을 받는 것으로 나타났다. 전류밀도가 15 mA/cm2 이상에서는 역 확산이 억제되어 전류효율이 증가하였다. ED 운전과정에서 전기삼투에 의한 물 이동량을 분석하였다. 물 이동량은 농축액과 희석액의 농도비에 비례하여 증가하는 것을 알 수 있었다. 농도비가 100 이상에서는 삼투압에 의한 물 이동량이 급격히 증가하여 200 g/L 이상의 농축액을 얻는데 한계가 있는 것으로 나타났다.

Keywords

Acknowledgement

본 연구는 2022년도 중소벤처기업부에서 지원하는 산학연 Collabo R&D 사업(S3301871)과 공주대학교 연구년(2022년) 사업에 의해 연구되었음.

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