TY - JOUR
T1 - Imaging of membrane concentration polarization by NaCl using 23Na nuclear magnetic resonance
AU - Zargar, Masoumeh
AU - Ujihara, Ryuta
AU - Vogt, Sarah J.
AU - Vrouwenvelder, Johannes S.
AU - Fridjonsson, Einar O.
AU - Johns, Michael L.
PY - 2020
Y1 - 2020
N2 - Forward 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.
AB - Forward 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.
KW - Concentration polarization
KW - Forward osmosis
KW - Magnetic resonance imaging
KW - Reverse osmosis
KW - Sodium
UR - http://www.scopus.com/inward/record.url?scp=85078226461&partnerID=8YFLogxK
U2 - 10.1016/j.memsci.2020.117868
DO - 10.1016/j.memsci.2020.117868
M3 - Article
AN - SCOPUS:85078226461
SN - 0376-7388
VL - 600
JO - Journal of Membrane Science
JF - Journal of Membrane Science
M1 - 117868
ER -