This paper documents the testing of a vacuum membrane distillation system intended for use with liquid desiccants. Liquid desiccants offer the possibility for low-energy, ambient temperature dehumidification. Effective desalination and purification of diluted desiccants outputs two important products: a concentrated desiccant for reuse in dehumidification and fresh water. In this study, vacuum membrane distillation was used in the laboratory to purify diluted liquid desiccants. Calcium chloride and magnesium chloride were the desiccants selected for testing. Desiccant solutions were pumped through the lumens of poly(vinylidene fluoride) (PVDF) hollow fiber membranes at varying feed inlet temperatures, solution velocity rates and vacuum set points during membrane distillation. An average flux of 8 kg m-2 h-1 was obtained using 30 wt% magnesium chloride solution at a temperature of 50 °C while applying vacuum to achieve 25 mbar absolute pressure on the air side of the membrane. The results are promising for the development of a full-scale vacuum membrane distillation process for desiccant solution regeneration and fresh water recovery. In addition, the recovered condensate was of sufficient quality for use in agricultural irrigation or drinking water.
Bibliographical noteKAUST Repository Item: Exported on 2021-11-29
Acknowledgements: The research reported in this publication was sponsored by King Abdullah University of Science and Technology (KAUST). The authors thank colleagues from the Nanostructured Polymeric Membrane (NPM) group, as well as the Water Desalination and Reuse Center (WDRC), and KAUST’s Core Labs for their help on equipment and analysis.
ASJC Scopus subject areas
- Filtration and Separation
- Analytical Chemistry