SCI和EI收录∣中国化工学会会刊

Chinese Journal of Chemical Engineering ›› 2020, Vol. 28 ›› Issue (12): 3011-3017.DOI: 10.1016/j.cjche.2020.05.012

• Separation Science and Engineering • Previous Articles     Next Articles

Experiments and insights of desalination by a freezing/thawing method at low subcooling

Jun Chen1,2, Jianjian Wu1, Jiafeng Xu1, Qing Yuan3, Bin Deng1, Changzhong Chen1, Zhi Li4   

  1. 1 Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds and Applications, College of Chemistry & Biology and Environmental Engineering, Xiangnan University, Chenzhou 423000, China;
    2 Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian 116024, China;
    3 School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059, China;
    4 Shandong Provincial Key Laboratory of Molecular Engineering, QiLu University of Technology(Shandong Academy of Sciences), Jinan 250353, China
  • Received:2020-01-03 Revised:2020-04-13 Online:2021-01-11 Published:2020-12-28
  • Contact: Jun Chen, Zhi Li
  • Supported by:
    This work is supported by the National Natural Science Foundation of China (21908116), the Hunan Provincial Natural Science Foundation of China (2019JJ50567), the projects of the Education Department of Hunan Province (17A199), the Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education (LOEC-201809), Scientific Research Foundation of Xiangnan University for High-Level Talents, and Development and application of nonferrous metal functional materials team.

Experiments and insights of desalination by a freezing/thawing method at low subcooling

Jun Chen1,2, Jianjian Wu1, Jiafeng Xu1, Qing Yuan3, Bin Deng1, Changzhong Chen1, Zhi Li4   

  1. 1 Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds and Applications, College of Chemistry & Biology and Environmental Engineering, Xiangnan University, Chenzhou 423000, China;
    2 Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian 116024, China;
    3 School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059, China;
    4 Shandong Provincial Key Laboratory of Molecular Engineering, QiLu University of Technology(Shandong Academy of Sciences), Jinan 250353, China
  • 通讯作者: Jun Chen, Zhi Li
  • 基金资助:
    This work is supported by the National Natural Science Foundation of China (21908116), the Hunan Provincial Natural Science Foundation of China (2019JJ50567), the projects of the Education Department of Hunan Province (17A199), the Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education (LOEC-201809), Scientific Research Foundation of Xiangnan University for High-Level Talents, and Development and application of nonferrous metal functional materials team.

Abstract: Desalination by freezing/thawing method was a very important method to obtain fresh water from sea water. In this work, desalination by freezing/thawing method was conducted with initial sodium chloride of 3.5 wt% in consideration of stirring speed, freezing time and subcooling. The subcooling ranged from 1.2 K to 4 K. The optimum conditions for desalination in this work were stirring speed of 200 r·min-1, freezing time of 120 min, and subcooling of 3 K. The results also showed that sodium chloride cannot be effectively removed by once freezing/thawing process. The maximum removal efficiency of sodium chloride was 64.3%. Two major reasons resulting in the impurity of obtained melted water by freezing/thawing method were proposed. The first reason was the inevitable adhesion of salt solution to the surface of ice, which could be removed easily by distilled water flushing. The second reason was that salt solution was heterogeneously wrapped in the accumulated ice, which was difficult to be removed by distilled water flushing. The liquid flushing method was proposed to verify the conjecture, and the results were in accordance with the two reasons mentioned above. Additional method, such as multiple flushing liquid method, was suggested to be used during the freezing/thawing process for effectively removing sodium chloride, and obtaining fresh water.

Key words: Desalination, Ice, Aqueous solution, Separation, Removal efficiency, Mechanism

摘要: Desalination by freezing/thawing method was a very important method to obtain fresh water from sea water. In this work, desalination by freezing/thawing method was conducted with initial sodium chloride of 3.5 wt% in consideration of stirring speed, freezing time and subcooling. The subcooling ranged from 1.2 K to 4 K. The optimum conditions for desalination in this work were stirring speed of 200 r·min-1, freezing time of 120 min, and subcooling of 3 K. The results also showed that sodium chloride cannot be effectively removed by once freezing/thawing process. The maximum removal efficiency of sodium chloride was 64.3%. Two major reasons resulting in the impurity of obtained melted water by freezing/thawing method were proposed. The first reason was the inevitable adhesion of salt solution to the surface of ice, which could be removed easily by distilled water flushing. The second reason was that salt solution was heterogeneously wrapped in the accumulated ice, which was difficult to be removed by distilled water flushing. The liquid flushing method was proposed to verify the conjecture, and the results were in accordance with the two reasons mentioned above. Additional method, such as multiple flushing liquid method, was suggested to be used during the freezing/thawing process for effectively removing sodium chloride, and obtaining fresh water.

关键词: Desalination, Ice, Aqueous solution, Separation, Removal efficiency, Mechanism