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NF/RO filtration of the hydrophobic ionogenic compound triclosan: Transport mechanisms and the influence of membrane fouling

Journal Article


Abstract


  • Filtration phenomena of the hydrophobic ionogenic compound triclosan by three commercially available

    nanofiltration (NF)/reverse osmosis (RO) membranes were investigated in this study. The separation

    behaviour of triclosan was systematically related to the compound physicochemical properties and the

    membranes as well as the solution pH. The influence of membrane fouling on the rejection of triclosan

    by the three selected NF/RO membranes were also examined using three model organic foulants and one

    model colloidal foulants. Having a unique hydrophobic ionogenic profile, even when triclosan was fully

    deprotonated at pH 10, considerable adsorption of the compound to the membrane could still be observed.

    The adsorption of triclosan to the membrane surface was a precursor for the diffusion of this compound

    through the membrane. In fact, under clean (virgin) membrane condition, considerable diffusive transport

    of triclosan through the loose nanofiltration NF-270 as well as the tight nanofiltration NF-90 membrane

    was clearly evident, leading to a lower rejection of triclosan by these membranes than expected based

    on their molecular weight cut-off or the size exclusion mechanism. This diffusive transport appears to be

    dependent on the thickness of the active layer and its porosity. As a result, no triclosanwas detected in the

    permeate samples from the reverse osmosis BW-30 membrane which has a thicker and more dense active

    skin layer. Results reported in this study also indicate that the formation of a hydrophobic fouling layer

    on the membrane surface could interfere with the soluteÃÂÿmembrane interaction, and thus, reduce the

    diffusive transport of triclosan across the membrane. Consequently, significant enhancement in rejection

    of triclosan was observed when the membranes were pre-fouled with the three model organic foulants

    namely bovine serum albumin (BSA), alginate and humic acid used in this study. In contrast, no discernible

    variation in rejectionwas observed when the membraneswere pre-fouled with hydrophilic silica colloids

    as compared to the clean membrane condition.

Publication Date


  • 2008

Citation


  • Nghiem, L. D. & Coleman, P. J. (2008). NF/RO filtration of the hydrophobic ionogenic compound triclosan: Transport mechanisms and the influence of membrane fouling. Separation and Purification Technology, 62 709-716.

Scopus Eid


  • 2-s2.0-48349087123

Ro Metadata Url


  • http://ro.uow.edu.au/engpapers/4224

Has Global Citation Frequency


Number Of Pages


  • 7

Start Page


  • 709

End Page


  • 716

Volume


  • 62

Abstract


  • Filtration phenomena of the hydrophobic ionogenic compound triclosan by three commercially available

    nanofiltration (NF)/reverse osmosis (RO) membranes were investigated in this study. The separation

    behaviour of triclosan was systematically related to the compound physicochemical properties and the

    membranes as well as the solution pH. The influence of membrane fouling on the rejection of triclosan

    by the three selected NF/RO membranes were also examined using three model organic foulants and one

    model colloidal foulants. Having a unique hydrophobic ionogenic profile, even when triclosan was fully

    deprotonated at pH 10, considerable adsorption of the compound to the membrane could still be observed.

    The adsorption of triclosan to the membrane surface was a precursor for the diffusion of this compound

    through the membrane. In fact, under clean (virgin) membrane condition, considerable diffusive transport

    of triclosan through the loose nanofiltration NF-270 as well as the tight nanofiltration NF-90 membrane

    was clearly evident, leading to a lower rejection of triclosan by these membranes than expected based

    on their molecular weight cut-off or the size exclusion mechanism. This diffusive transport appears to be

    dependent on the thickness of the active layer and its porosity. As a result, no triclosanwas detected in the

    permeate samples from the reverse osmosis BW-30 membrane which has a thicker and more dense active

    skin layer. Results reported in this study also indicate that the formation of a hydrophobic fouling layer

    on the membrane surface could interfere with the soluteÃÂÿmembrane interaction, and thus, reduce the

    diffusive transport of triclosan across the membrane. Consequently, significant enhancement in rejection

    of triclosan was observed when the membranes were pre-fouled with the three model organic foulants

    namely bovine serum albumin (BSA), alginate and humic acid used in this study. In contrast, no discernible

    variation in rejectionwas observed when the membraneswere pre-fouled with hydrophilic silica colloids

    as compared to the clean membrane condition.

Publication Date


  • 2008

Citation


  • Nghiem, L. D. & Coleman, P. J. (2008). NF/RO filtration of the hydrophobic ionogenic compound triclosan: Transport mechanisms and the influence of membrane fouling. Separation and Purification Technology, 62 709-716.

Scopus Eid


  • 2-s2.0-48349087123

Ro Metadata Url


  • http://ro.uow.edu.au/engpapers/4224

Has Global Citation Frequency


Number Of Pages


  • 7

Start Page


  • 709

End Page


  • 716

Volume


  • 62