The Art of Surface Modification of Synthetic Polymeric Membranes

Journal of Applied Polymer Science (Impact Factor: 1.77). 01/2010; 115(2). DOI: 10.1002/app.31108

ABSTRACT The development in the area of surface modification of polymeric synthetic membranes since 2000 is reviewed. Many patents, articles, and reviews have been written on the development in the area of surface modifi-cation of polymeric synthetic membranes subjected to RO, UF, NF, gas separation (GS), and biomedical applications, mainly since 2000, but recently more attention has been given to the modification of their surfaces to obtain desira-ble results. In particular, most emphasis has been given to plasma treatment, grafting of polymers on the surface, and modifying the surfaces by adding SMMs (surface-modify-ing molecules). New additives are synthesized to make the polymeric membrane surfaces either to be more hydro-philic or hydrophobic, aimed at improvement in selectivity and permeability of the membranes for GS, NF, and RO. Improvement in antifouling by surface modification is also a popular topic in the membrane industries. In the last 8 years, tremendous research efforts have been made on the development of antifouling membranes. V C 2009 Wiley Peri-odicals, Inc. J Appl Polym Sci 115: 855–895, 2010

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    • "In general, membrane modification approaches can be grouped into four categories, i.e., blending additives, physical coating, chemical coating, and heterogeneous reactions [2] [3]. Minor amount of hydrophilic additives such as polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) blended into the membrane cast solution seems to be the simplest modification method. "
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    ABSTRACT: Nanoparticle embedded polysulfone ultrafiltration (UF) membranes were prepared by using the in situ embedment method, and the anti-biofouling properties of the prepared membranes were evaluated by conducting bacteria adhesion test, bacterium inactivation test and biofilm formation test separately. Among the several aluminum and/or silicon oxide nanoparticles tested, alumina (Al2O3) and Linda type L (LTL) zeolite nanoparticles were successfully embedded which could be evenly dispersed on membrane surface with high coverage ratio (38% and 49%, respectively) and were resistant to hydraulic shear detachment. The water contact angles for the nanoparticle embedded membranes (UF-Al2O3 and UF-LTL) and the control membrane (UF-C) were 57°, 40° and 66°, respectively. Owing to the higher surface hydrophilicity, both UF-Al2O3 and UF-LTL demonstrated a higher filterability than UF-C. Biofouling was inhibited on both UF-Al2O3 and UF-LTL, indicated by the lower Pseudomonas aeruginosa biofilm formation rate. Further investigation showed that both UF-Al2O3 and UF-LTL exhibited a high anti-adhesion efficiency to both Escherichia coli and P. aeruginosa, but no bacteriocidal effect on E. coli. The anti-biofouling ability of UF-Al2O3 and UF-LTL mainly benefited from the anti-adhesion ability attributed to the embedded nanoparticles. The improved anti-adhesion ability could not be simply explained by the enhanced hydrophilicity.
    Desalination 06/2015; 365. DOI:10.1016/j.desal.2015.02.023 · 3.76 Impact Factor
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    • "The negative surface charge of the membrane prevents the deposition of the negatively charged colloidal particles (proteins, lipids and amino acids etc.,) on the membrane surface by electrostatic repulsion, which can slow down the membrane fouling process49. It is also reported that the membrane fouling can be reduced by increasing the negative surface density of the membrane50. TOC removal efficiency of the control membrane was also increased with time, which may due to the pore constriction or development of a cake layer (fouling) on the membrane surface51. "
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    ABSTRACT: Bio-fouling is a serious problem in many membrane-based separation processes for water and wastewater treatment. Current state of the art methods to overcome this are to modify the membranes with either hydrophilic additives or with an antibacterial compound. In this study, we propose and practise a novel concept to prevent bio-fouling by developing a killing and self-cleaning membrane surface incorporating antibacterial silver nanoparticles and highly hydrophilic negatively charged carboxylic and amine functional groups. The innovative surface chemistry helps to reduce the contact angle of the novel membrane by at least a 48% and increase the pure water flux by 39.4% compared to the control membrane. The flux drop for the novel membrane is also lower (16.3% of the initial flux) than the control membrane (55.3% of the initial flux) during the long term experiments with protein solution. Moreover, the novel membrane continues to exhibit inhibition to microbes even after 1320 min of protein filtration. Synthesis of self-cleaning ultrafiltration membrane with long lasting properties opens up a viable solution for bio-fouling in ultrafiltration application for wastewater purification.
    Scientific Reports 10/2014; 4:6555. DOI:10.1038/srep06555 · 5.58 Impact Factor
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    • "Additives are commonly used to improve porosity and antifouling behavior. For example poly(vinylpyrrolidone) (PVP) [13] [14], PEG [15] [16], and LiClO 4 [17] etc. are commonly used as pore forming agents in fabrication of ultrafiltration and microfiltration membranes due to their good water solubility [18]. The partial or complete leaching of these additives in the coagulation bath contributes to the increased porosity of the casted membranes . "
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    ABSTRACT: Blending selected polymer materials in the membrane fabrication process has been widely investigated for dense film membrane in order to improve the membrane gas separation performance. However, such a strategy has not been fully explored on hollow fiber membrane, which is preferred in industry for gas separation. In this study, Matrimid® 5218 hollow fibers with 0–12 wt% additive (PEG or PEO–PDMS copolymer) were fabricated via phase inversion technique. The effects of additives on the hollow fiber׳s gas transport properties were discussed in terms of the membrane morphology and surface composition, gas separation performance as well as plasticization and aging property. Both additives showed significant impact on the membrane structure, particularly influencing the skin layer of the hollow fiber. However, the copolymer also displayed surface aggregation behavior which resulted in the modification of skin layer composition. The increase in the concentration of PEG improved the CO2 permeance from 21 GPU (without PEG) to 37 GPU (with 12 wt% PEG) and the hollow fibers with 12 wt% PEO–PDMS copolymer displayed a doubled CO2/N2 selectivity compared to the fibers without the additive. Addition of PEG reduced the CO2 plasticization pressure while PEO–PDMS improved the plasticization resistance of hollow fibers.
    Journal of Membrane Science 10/2014; 468:107–117. DOI:10.1016/j.memsci.2014.05.024 · 5.06 Impact Factor
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