TY - JOUR
T1 - Predicting the Rejection of Major Seawater Ions by Spiral-Wound Nanofiltration Membranes
AU - Fridman-Bishop, Noga
AU - Nir, Oded
AU - Lahav, Ori
AU - Freger, Viatcheslav
N1 - Publisher Copyright:
© 2015 American Chemical Society.
PY - 2015/7/21
Y1 - 2015/7/21
N2 - Seawater nanofiltration (SWNF) generates a softened permeate stream and a retentate stream in which the multivalent ions accumulate, offering opportunities for practical utilization of both streams. This study presents an approach to simulation of SWNF including all major seawater ions (Na+, Cl-, Ca2+, Mg2+, and SO42-) based on the Nernst-Planck equation, and uses it for permeate and retentate streams composition prediction. The number of degrees of freedom in the system was reduced by assuming a very high ionic permeability for Na+, which only weakly affected the other parameters in the system. Two alternatives were examined to analyze the importance of concentration dependence of ion permeabilities: The assumption of constant ion permeabilities resulted in a reasonable fit with experimental data. However, for the permeate composition the overall fit was significantly improved (P < 0.0001) when the permeabilities of Ca2+ and Mg2+ were allowed to depend on the ratio of their total concentration to Na+. This type of dependence emphasizes the strong interaction of divalent ions with the membrane and its effect on the membrane fixed charge through screening or charge reversal. When this effect was included, model predictions closely matched the experimental results obtained, corroborating the phenomenological approach proposed in this study.
AB - Seawater nanofiltration (SWNF) generates a softened permeate stream and a retentate stream in which the multivalent ions accumulate, offering opportunities for practical utilization of both streams. This study presents an approach to simulation of SWNF including all major seawater ions (Na+, Cl-, Ca2+, Mg2+, and SO42-) based on the Nernst-Planck equation, and uses it for permeate and retentate streams composition prediction. The number of degrees of freedom in the system was reduced by assuming a very high ionic permeability for Na+, which only weakly affected the other parameters in the system. Two alternatives were examined to analyze the importance of concentration dependence of ion permeabilities: The assumption of constant ion permeabilities resulted in a reasonable fit with experimental data. However, for the permeate composition the overall fit was significantly improved (P < 0.0001) when the permeabilities of Ca2+ and Mg2+ were allowed to depend on the ratio of their total concentration to Na+. This type of dependence emphasizes the strong interaction of divalent ions with the membrane and its effect on the membrane fixed charge through screening or charge reversal. When this effect was included, model predictions closely matched the experimental results obtained, corroborating the phenomenological approach proposed in this study.
UR - http://www.scopus.com/inward/record.url?scp=84937501044&partnerID=8YFLogxK
U2 - 10.1021/acs.est.5b00336
DO - 10.1021/acs.est.5b00336
M3 - 文章
C2 - 26107401
AN - SCOPUS:84937501044
VL - 49
SP - 8631
EP - 8638
JO - Environmental Science & Technology
JF - Environmental Science & Technology
SN - 0013-936X
IS - 14
ER -