Intrinsic properties and performances of NF270 and XLE membranes for water filtration

Diop, Saidou N.; Diallo, Mouhamadou Baïla; Diawara, Courfia K.; Cot, Didier

doi:10.2166/ws.2011.024

Cited by 9 publications

(6 citation statements)

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“…The comparable value of permeability obtained after chemical with the virgin one shows that the NF membranes can be used for other filtrations. The NF membrane permeability is relatively high [10][11][12] compared to the LPRO one.…”

Section: Permeability Evolutionmentioning

confidence: 95%

“…Membrane separation procedures based on pressure driving force such as nanofiltration (NF) and reverse osmosis (RO) have been recognized as efficient treatment methods for the production of drinking water [9]. Yet, the performance of these separation techniques is linked to the intrinsic properties of the membranes [10] and the choice of the best membrane which depends on the quality of water to be treated and operational conditions [4,6].…”

Section: Introductionmentioning

confidence: 99%

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Performance of Nanofiltration (NF) and Low Pressure Reverse Osmosis (LPRO) Membranes in the Removal of Fluorine and Salinity from Brackish Drinking Water

Diawara¹,

Diop²,

Diallo³

et al. 2011

JWARP

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Certain areas in Senegal have a serious problem of high fluoride and salinity in underground water because of soil properties. This water currently used for drink has a bad taste on consumption and caused diseases like dental fluorosis and skeletal fluorosis. A membrane filtration plant constructed by Pall Corporation was improved through nanofiltration (NF) and Low Pressure Reverse Osmosis (LPRO). Both NF and LPRO membranes were shown applicable for salinity and fluoride ions removal from brackish and high fluorinated drinking water in a remote community. The NF membrane has given a fluorine retention rate varying between 63.3% and 71% while the LPRO membrane allow to reach 97 to 98.9% for fluorine rejection. Highest salinity rejection rates expressed through conductivity measurements are around 46% and 97% for respectively NF and LPRO

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Section: Permeability Evolutionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Performance of Nanofiltration (NF) and Low Pressure Reverse Osmosis (LPRO) Membranes in the Removal of Fluorine and Salinity from Brackish Drinking Water

Diawara¹,

Diop²,

Diallo³

et al. 2011

JWARP

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show abstract

“…All the measurements were carried out at pH 6. Streaming potential is usually measured using as electrolyte KCl solutions in a low concentration range (0.001 to 0.01M) as reported in literature for the membrane NF270 used in this study [21][22][23][24][25][26][27]. However, those electrolyte solutions are not representative of the conditions applied in this study during NF operation.…”

Section: Streaming Potential Measurementmentioning

confidence: 99%

Nanofiltration separation of polyvalent and monovalent anions in desalination brines

Pérez-González

Ibáñez

Gómez³

et al. 2015

Journal of Membrane Science

152

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This work, as part of a global membrane process for the recovery of alkali and acids from reverse osmosis (RO) desalination brines, focuses on the nanofiltration (NF) separation of polyvalent and monovalent anions, more specifically sulfate and chloride. This pretreatment stage plays a key role in the whole recovery process. Working with model brines simulating the concentration of RO concentrates, 0.2-1.2M chloride concentration and 0.1M sulfate concentration, the experimental performance and modeling of the NF separation is reported. The study has been carried out with the NF270 (Dow Filmtec) membrane. The effect of operating pressure (500-2000 kPa), ionic strength (0.4-1.3 M) and chloride initial concentration (0.2-1.2 M) on the membrane separation capacity has been investigated. Finally, the Donnan Steric Pore Model (DSPM) together with experimentally determined parameters: effective pore radius (); thickness of the membrane effective layer (į) and effective membrane charge density (), was proved accurate enough to satisfactorily describe the experimental results. In this work we provide for the first time the analysis of partitioning effects and transport mechanism in the NF separation of sulfate and chloride anions in concentrations that simulate those found in RO desalination brines.

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“…To experimentally assess the effect of surface charge on salt rejection, we performed NF using NF270 membranes before and after modification by polycation adsorption. Native NF270 membranes have a negative surface charge, − whereas adsorption of PAH introduces positive charge on the surface.…”

Section: Resultsmentioning

confidence: 99%

Deviations from Electroneutrality in Membrane Barrier Layers: A Possible Mechanism Underlying High Salt Rejections

et al. 2016

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Reverse osmosis and nanofiltration (NF) employ composite membranes whose ultrathin barrier layers are significantly more permeable to water than to salts. Although solution-diffusion models of salt transport through barrier layers typically assume ubiquitous electroneutrality, in the case of ultrathin selective skins and low ion partition coefficients, space-charge regions may occupy a significant fraction of the membrane barrier layer. This work investigates the implications of these deviations from electroneutrality on salt transport. Both immobile external surface charge and unequal cation and anion solvation energies in the barrier layer lead to regions with excess mobile charge, and the size of these regions increases with decreasing values of either feed concentrations or ion partition coefficients. Moreover, the low concentration of the more excluded ion in the space-charge region can greatly increase resistance to salt transport to enhance salt rejection during NF. These effects are especially pronounced for membranes with a fixed external surface charge density whose sign is the same as that of the more excluded ion in a salt. Because of the space-charge regions, the barrier-layer resistance to salt transport initially rises rapidly with increasing barrier thickness and then plateaus or even declines within a certain thickness range. This trend in resistance implies that thin, defect-free barrier layers will exhibit higher salt rejections than thicker layers during NF at a fixed transmembrane pressure. Deviations from electroneutrality are consistent with both changes in NF salt rejections that occur upon changing the sign of the membrane fixed external surface charge, and CaCl2 rejections that in some cases may first decrease, then increase and then decrease again with increasing CaCl2 concentrations in NF feed solutions.

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Intrinsic properties and performances of NF270 and XLE membranes for water filtration

Cited by 9 publications

References 0 publications

Performance of Nanofiltration (NF) and Low Pressure Reverse Osmosis (LPRO) Membranes in the Removal of Fluorine and Salinity from Brackish Drinking Water

Performance of Nanofiltration (NF) and Low Pressure Reverse Osmosis (LPRO) Membranes in the Removal of Fluorine and Salinity from Brackish Drinking Water

Nanofiltration separation of polyvalent and monovalent anions in desalination brines

Deviations from Electroneutrality in Membrane Barrier Layers: A Possible Mechanism Underlying High Salt Rejections

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