Imaging of membrane concentration polarization by NaCl using 23Na nuclear magnetic resonance
Vogt, Sarah J.
Vrouwenvelder, Johannes S.
Fridjonsson, Einar O.
Johns, Michael L.
KAUST DepartmentEnvironmental Science and Engineering Program
Water Desalination and Reuse Research Center (WDRC)
Biological and Environmental Sciences and Engineering (BESE) Division
Online Publication Date2020-01-21
Print Publication Date2020-04
Embargo End Date2022-01-21
Permanent link to this recordhttp://hdl.handle.net/10754/661362
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AbstractForward osmosis (FO) and reverse osmosis (RO) membrane processes differ in their driving forces: osmotic pressure versus hydraulic pressure. Concentration polarization (CP) can adversely affect both performance and lifetime in such membrane systems. In order to mitigate against CP, the extent and severity of it need to be predicted more accurately through advanced online monitoring methodologies. Whilst a variety of monitoring techniques have been used to study the CP mechanism, there is still a pressing need to develop and apply non-invasive, in situ techniques able to produce quantitative, spatially resolved measurements of heterogeneous solute concentration in, and adjacent to, the membrane assembly as caused by the CP mechanism. To this end, 23Na magnetic resonance imaging (MRI) is used to image the sodium ion concentration within, and near to, both FO and RO composite membranes for the first time; this is also coupled with 1H MRI mapping of the corresponding water distribution. As such, it is possible to directly image salt accumulation due to CP processes during desalination. This was consistent with literature expectations and serves to confirm the suitability of 23Na MRI as a novel non-invasive technique for CP studies.
CitationZargar, M., Ujihara, R., Vogt, S. J., Vrouwenvelder, J. S., Fridjonsson, E. O., & Johns, M. L. (2020). Imaging of membrane concentration polarization by NaCl using 23Na nuclear magnetic resonance. Journal of Membrane Science, 600, 117868. doi:10.1016/j.memsci.2020.117868
SponsorsThe authors acknowledge the facilities and scientific and technical assistance of the National Imaging Facility, a National Collaborative Research Infrastructure Strategy (NCRIS) capability, at the Centre for Microscopy, Characterisation and Analysis, The University of Western Australia. Funding from the Australian Research Council, the Forrest Research Foundation (for R. Ujihara) and the King Abdullah University of Science and Technology (KAUST) is gratefully acknowledged.
JournalJournal of Membrane Science