Nanofiltration of Natural Organic Matter: pH and Ionic Strength Effects

Braghetta, Anne; DiGiano, Francis A.; Ball, William P.

doi:10.1061/(asce)0733-9372(1997)123:7(628)

Cited by 227 publications

(116 citation statements)

References 32 publications

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“…These results of lower fluxes with an increase in PAC dosage conflict with those reported in the literature [3]. However, studies have shown that the role of PAC in flux improvement depends on the amount of PAC added [30], solution chemistry [31], and type and concentration of dissolved organic compounds [32].…”

Section: Transmembrane Pressure (Tmp) and Fluxcontrasting

confidence: 56%

Flux and performance improvement in a submerged anaerobic membrane bioreactor (SAMBR) using powdered activated carbon (PAC)

Akram

Stuckey

2008

Process Biochemistry

150

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Section: Transmembrane Pressure (Tmp) and Fluxcontrasting

confidence: 56%

Flux and performance improvement in a submerged anaerobic membrane bioreactor (SAMBR) using powdered activated carbon (PAC)

Akram

Stuckey

2008

Process Biochemistry

150

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“…Therefore, at a sufficiently high ionic strength, NOM macromolecules are not only rigid, compact, and spherocolloidal but can also adsorb more effectively to the membrane surface (34,35,41). Because NOM retention by the NF-270 membrane (measured as TOC) was approximately 90% at both low and high ionic strength solutions, a layer of NOM is expected to form on the membrane surface.…”

Section: Retention In Presence Of Background Natural Organic Mattermentioning

confidence: 99%

“…As discussed in the previous section, ionic strength does not influence the membrane pore size and the partitioning process between trace organics and the membrane polymer. However, ionic strength is known to affect the electrostatic interactions between functional groups of both NOM and the membrane polymer (35), which can possibly influence the NOM -membrane and NOM -trace organic interactions.…”

Section: Retention In Presence Of Background Natural Organic Mattermentioning

confidence: 99%

“…Results reported here suggest that, at the conditions examined, ionic strength has a negligible effect on nanofiltration of hormone mimicking trace organic contaminants. However, it is important to note that ionic strength can still influence the charge screening of membrane functional groups and, hence, the retention of charged organic solutes (35).…”

Section: Effect Of Ionic Strength On Retentionmentioning

confidence: 99%

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Nanofiltration of Hormone Mimicking Trace Organic Contaminants

Nghiem

Schäfer

Elimelech

2005

Separation Science and Technology

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The removal mechanisms of three hormone mimicking organic compounds by nanofiltration (NF) membranes have been examined. Two NF membranes having different pore sizes were used in laboratory-scale nanofiltration experiments with feed solutions spiked with a hormone mimicking compound-nonylphenol, tertbutylphenol, or bisphenol A. Retention of the compounds was determined at various solution chemistries, namely aqueous solution pH, ionic strength, and presence of natural organic matter. The nanofiltration behavior of the selected hormone mimicking compounds appears similar to that of natural hormones as reported in our previous work. While the solution pH can dramatically influence the retention of hormone mimicking compounds by a loose NF membrane, ionic strength does not affect the nanofiltration of such contaminants. However, in the presence of natural organic matter in the feed solution, ionic strength appears to play a significant role in solute-solute and solute-membrane interactions, resulting in increased retention due to partitioning of the hormone mimicking compounds onto organic matter at a higher ionic strength.

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“…The con¯icting results may be due to the type and the amount of PAC added (Jacangelo et al, 1995), type of NOM as well as DOC concentration (Chang et al, 1998), solution chemistry (Braghetta et al, 1997), pH (Chang et al, 1998), and characteristics of the membrane used. It is unclear as to the reason that the addition of PAC in the integrated PAC-UF system aects¯ux decline.…”

Section: Eect Of Humic Substance Hydrophobicitymentioning

confidence: 99%

Effects of humic substance characteristics on UF performance

2000

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AbstractÐThe role of humic substances in general and hydrophobicity of humic substances in particular on membrane permeate¯ux is unclear. The main goal of the present study is to evaluate the eect of fractionated humic substances on ultra®ltration (UF) performance. A commercial humic solution was subjected to a hydrophobic resin for fractionation of the hydrophobic and hydrophilic fraction. These fractions were further fractionated into dierent molecular wight groups, using gel ®ltration chromatography. The hydrophobic fraction accounts for 85% organic carbon recovered and has a signi®cantly high THM (trihalomethane) formation potential, or 190 mg/mg C. The hydrophilic fraction exhibits the worst¯ux decline despite little solute rejection. The results of molecular weight fractionation of both hydrophobic and hydrophilic fractions further indicate that those molecules with the largest molecular weight (6.5±22.6 kDa) exhibit the worst¯ux decline. The UF system evaluated is unable to remove a signi®cant portion of THM precursors, resulting in potentially high THMs in the permeate. The use of powdered activated carbon (PAC) for the pretreatment of hydrophobic/ hydrophilic humic substances or in an integrated PAC-UF system exhibits an enhanced membrane fouling. #

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Nanofiltration of Natural Organic Matter: pH and Ionic Strength Effects

Cited by 227 publications

References 32 publications

Flux and performance improvement in a submerged anaerobic membrane bioreactor (SAMBR) using powdered activated carbon (PAC)

Flux and performance improvement in a submerged anaerobic membrane bioreactor (SAMBR) using powdered activated carbon (PAC)

Nanofiltration of Hormone Mimicking Trace Organic Contaminants

Effects of humic substance characteristics on UF performance

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