Boron removal from seawater using high rejection SWRO membranes — impact of pH, feed concentration, pressure, and cross-flow velocity

Köseoğlu, H.; Kabay, Nalan; Yüksel, Mithat; Sarp, Sarper; Arar, Özgür; Kitiş, Mehmet

doi:10.1016/j.desal.2007.06.029

Cited by 122 publications

(50 citation statements)

References 23 publications

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“…The rejections of boron and sodium by virgin and cleaned membranes were investigated as functions of permeate flux, temperature, and solution pH. In good agreement with the literature (Hung et al, 2009;Koseoglu et al, 2008), boron rejection was strongly affected by flux, temperature and feed solution pH. Boron rejection by the virgin ESPA2 varied from 45 to 72% when the permeate flux increased from 10 to 60 LMH.…”

Section: The Rejection Of Boron and Sodiumsupporting

confidence: 60%

Chemical cleaning effects on properties and separation efficiency of an RO membrane

Tu¹,

Chivas²,

Nghiem³

2015

Membr. Water Treat.

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This study aims to investigate the impacts of chemical cleaning on the performance of a reverse osmosis membrane. Chemicals used for simulating membrane cleaning include a surfactant (sodium dodecyl sulfate, SDS), a chelating agent (ethylenediaminetetraacetic acid, EDTA), and two proprietary cleaning formulations namely MC3 and MC11. The impact of sequential exposure to multiple membrane cleaning solutions was also examined. Water permeability and the rejection of boron and sodium were investigated under various water fluxes, temperatures and feedwater pH. Changes in the membrane performance were systematically explained based on the changes in the charge density, hydrophobicity and chemical structure of the membrane surface. The experimental results show that membrane cleaning can significantly alter the hydrophobicity and water permeability of the membrane; however, its impacts on the rejections of boron and sodium are marginal. Although the presence of surfactant or chelating agent may cause decreases in the rejection, solution pH is the key factor responsible for the loss of membrane separation and changes in the surface properties. The impact of solution pH on the water permeability can be reversed by applying a subsequent cleaning with the opposite pH condition. Nevertheless, the impacts of solution pH on boron and sodium rejections are irreversible in most cases. Abstract. This study aims to investigate the impacts of chemical cleaning on the performance of a reverse osmosis membrane. Chemicals used for simulating membrane cleaning include a surfactant (sodium dodecyl sulfate, SDS), a chelating agent (ethylenediaminetetraacetic acid, EDTA), and two proprietary cleaning formulations namely MC3 and MC11. The impact of sequential exposure to multiple membrane cleaning solutions was also examined. Water permeability and the rejection of boron and sodium were investigated under various water fluxes, temperatures and feedwater pH. Changes in the membrane performance were systematically explained based on the changes in the charge density, hydrophobicity and chemical structure of the membrane surface. The experimental results show that membrane cleaning can significantly alter the hydrophobicity and water permeability of the membrane; however, its impacts on the rejections of boron and sodium are marginal. Although the presence of surfactant or chelating agent may cause decreases in the rejection, solution pH is the key factor responsible for the loss of membrane separation and changes in the surface properties. The impact of solution pH on the water permeability can be reversed by applying a subsequent cleaning with the opposite pH condition. Nevertheless, the impacts of solution pH on boron and sodium rejections are irreversible in most cases.

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Section: The Rejection Of Boron and Sodiumsupporting

confidence: 60%

Chemical cleaning effects on properties and separation efficiency of an RO membrane

Tu¹,

Chivas²,

Nghiem³

2015

Membr. Water Treat.

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“…3), leading to an enhanced electrostatic interaction with charged solute [22]. Previous studies investigating the effects of solution pH on boron rejection have focused almost exclusively on RO membranes [13,17,[24][25][26][27][28][29][30]. By assessing a full NF/RO membrane spectrum, results reported in Fig.…”

Section: Effects Of Phmentioning

confidence: 95%

Coupling effects of feed solution pH and ionic strength on the rejection of boron by NF/RO membranes

Nghiem

Chivas

2011

Chemical Engineering Journal

139

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a b s t r a c tThe coupling effects of solution pH and ionic strength on boron rejection by nanofiltration (NF) and reverse osmosis (RO) membranes were investigated. Two NF membranes (namely NF270 and NF90) and three RO membranes (namely BW30, SW30 and UTC80) were used to provide a full spectrum of NF/RO membranes. The rejection of boron by all five membranes was pH-dependent. The dependency of boron rejection on the feed solution pH became much more substantial as the nominal salt (sodium or calcium) rejection value of the membrane decreased. At pH 11, boron rejections by the NF90 and the NF270 membranes were only 10% and 30% lower than those by the other three RO membranes, respectively. On the other hand, the permeabilities of the two NF membranes investigated here were 3-11 times higher than those of the RO membranes. The reported data suggest a possibility of using NF membranes for the second pass in seawater desalination applications to avoid over-demineralisation of the final product water. The reported results also reveal an intricate interplay among the feed solution pH, ionic strength and their effects on the rejection of boron by NF/RO membranes. At pH 10, which is immediately above the intrinsic pK a value (9.23) of boric acid, as the feed solution ionic strength increased up to 42.5 mM, a considerable increase in boron rejection by both the NF270 and the BW30 membranes was observed. This phenomenon could be attributed to the reduction in the apparent pK a of boric acid as the ionic strength increased, which possibly resulted in the observed increase in boron rejection at pH 10. Results reported here suggest that the rejection of boron in the second pass could be further optimised by increasing the feed solution pH and allowing for a marginally higher salt passage in the first pass.Crown

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“…Boron rejection by RO membranes is mostly governed by the membrane used, feed solution pH, operating pressure, temperature, and membrane fouling [7,[13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Enhanced boron rejection by NF/RO membranes by complexation with polyols: Measurement and mechanisms

Chivas

Nghiem

2013

Desalination

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Boron rejection by nanofiltration (NF) and reverse osmosis (RO) membranes in the presence of glycerol, mannitol and sorbitol was investigated as a function of feed solution pH and boron:polyol molar ratio. In the presence of polyols, significant boron rejection improvement was obtained and the extent of the impact was directly related to the stability constant of the boron-polyol complex. Polyols could complex with boron in either the boric acid or borate anion forms; however the complexation between polyol and boric acid appeared to be incomplete. With and without the presence of polyols, boron rejection was strongly pH dependent. The increase in boron rejection due to polyol addition was higher for the NF membrane compared to the RO membrane. A boron:polyol molar ratio of 1:1 appeared to be adequate. The presence of polyols did not cause any observable membrane fouling. Results reported here suggest that the addition of polyols could allow NF membranes to be effectively used for boron removal. AbstractBoron rejection by nanofiltration (NF) and reverse osmosis (RO) membranes in the presence of glycerol, mannitol and sorbitol was investigated as a function of feed solution pH and boron:polyol molar ratio. In the presence of polyols, significant boron rejection improvement was obtained and the extent of the impact was directly related to the stability constant of the boron-polyol complex. Polyols could complex with boron in either the boric acid or borate anion forms; however the complexation between polyol and boric acid appeared to be incomplete.With and without the presence of polyols, boron rejection was strongly pH dependent. The increase in boron rejection due to polyol addition was higher for the NF membrane compared to the RO membrane. A boron:polyol molar ratio of 1:1 appeared to be adequate. The presence of polyols did not cause any observable membrane fouling. Results reported here suggest that the addition of polyols could allow NF membranes to be effectively used for boron removal.

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Boron removal from seawater using high rejection SWRO membranes — impact of pH, feed concentration, pressure, and cross-flow velocity

Cited by 122 publications

References 23 publications

Chemical cleaning effects on properties and separation efficiency of an RO membrane

Chemical cleaning effects on properties and separation efficiency of an RO membrane

Coupling effects of feed solution pH and ionic strength on the rejection of boron by NF/RO membranes

Enhanced boron rejection by NF/RO membranes by complexation with polyols: Measurement and mechanisms

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