Highly Hydrophilic Polyvinylidene Fluoride (PVDF) Ultrafiltration Membranes via Postfabrication Grafting of Surface-Tailored Silica Nanoparticles

Abstract

Polyvinylidene fluoride (PVDF) has drawn much attention as a predominant ultrafiltration (UF) membrane material due to its outstanding mechanical and physicochemical properties. However, current applications suffer from the low fouling resistance of the PVDF membrane due to the intrinsic hydrophobic property of the membrane. The present study demonstrates a novel approach for the fabrication of a highly hydrophilic PVDF UF membrane via postfabrication tethering of superhydrophilic silica nanoparticles (NPs) to the membrane surface. The pristine PVDF membrane was grafted with poly(methacrylic acid) (PMAA) by plasma induced graft copolymerization, providing sufficient carboxyl groups as anchor sites for the binding of silica NPs, which were surface-tailored with amine-terminated cationic ligands. The NP binding was achieved through a remarkably simple and effective dip-coating technique in the presence or absence of the N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS) cross-linking process. The properties of the membrane prepared from the modification without EDC/NHS cross-linking were comparable to those for the membrane prepared with the EDC/NHS cross-linking. Both modifications almost doubled the surface energy of the functionalized membranes, which significantly improved the wettability of the membrane and converted the membrane surface from hydrophobic to highly hydrophilic. The irreversibly bound layer of superhydrophilic silica NPs endowed the membranes with strong antifouling performance as demonstrated by three sequential fouling filtration runs using bovine serum albumin (BSA) as a model organic foulant. The results suggest promising applications of the postfabrication surface modification technique in various membrane separation areas.

Hydrophilicity, morphology and excellent adsorption ability of poly(vinylidene fluoride) membranes induced by graphene oxide and polyvinylpyrrolidone

“…The PVDF composite membrane exhibited high porosity and improved water permeation due to the high hydrophilicity of the nanoparticles. Similarly, Liang et al [21] developed a novel approach for the fabrication of a highly hydrophilic PVDF ultrafiltration membranes. In their approach, the pristine PVDF membrane was first grafted with poly(methacrylic acid) (PMMA) by plasma induced graft copolymerization, then the functionalized silica nanoparticles were anchored on the membrane surface and consequently, significantly improved wettability of the membrane was achieved and the membrane surface was converted from hydrophobic to highly hydrophilic.…”

Anaerobic digestion of pulp and paper mill wastes – An overview of the developments and improvement opportunities

“…For instance, fouling resistance of PVDF can be enhanced via attachment of appropriate materials to the surface of the membrane. Liang et al (2013) [162] improved the hydrophobicity of the PVDF through post fabrication tethering of silica nanoparticles (NPs) to the membrane surface in order to form a highly hydrophilic mem brane. Electrical treatment of the membrane surface can also be a good candidate to limit the hydrophobic behavior of the membranes, and so less attachment of the solutes to the mem brane surface.…”

Fabrication and anti-biofouling properties of alumina and zeolite nanoparticle embedded ultrafiltration membranes

“…In addition to increasing membrane permeability, hydrophilicity is one of the most important properties of membranes that determine the antifouling ability [16,36,37]. A number of previous studies have attempted to increase membrane hydrophilicity by doping nanoparticles mostly through the blending additive method.…”

“…The nanomaterials are either blended in the membrane matrix or coated on the membrane surface usually with the aid of tethering chemicals. Previous studies showed that inorganic nanoparticles, including alumina (Al 2 O 3 ) [6][7][8][9][10], zinc oxide (ZnO) [11][12][13][14], silicon dioxide (SiO 2 ) [15][16][17], titanium dioxide (TiO 2 ) [18][19][20] and zeolites [21,22], could endow membranes with more hydrophilic surface. In addition, nanomaterials might be able to impart membranes with excellent anti-biofouling ability [23].…”