Pure Polyethersulfone Membrane Research Articles

Preparation of hydrophilic nanofiltration membranes for removal of pharmaceuticals from water.

Asymmetric polyethersulfone (PES) nanofiltration membranes were prepared via phase inversion technique. PES polymer, Brij 58 as surfactant additive, polyvinylpyrrolidone (PVP) as pore former and 1-methyl-2-pyrrolidone (NMP) as solvent were used in preparation of the casting solutions. Distillated water was used as the gelation media. The scanning electron microscopy (SEM) images and measurements of contact angle (CA) and zeta potential were used to characterize the prepared membranes. Also performance of the membranes was examined by determining the pure water flux (PWF) and pharmaceuticals rejection. The addition of Brij 58 to the casting solution resulted in formation of the membranes with higher thickness and more porous structure in the sublayer in comparison with the net PES membrane. The surface hydrophilicity of the membranes was remarkably enhanced via the presence of Brij 58 in the casting solution, so that, the contact angel diminished from 74.7° to 28.3° with adding 6 wt. % of Brij 58 to the casting solution. The addition of Brij 58 to the casting solution resulted in formation of the membranes with superior PWF and higher rejection of amoxicillin and ceftriaxone in comparison with the pure PES membrane.

Improving permeability and antifouling performance of polyethersulfone ultrafiltration membrane by incorporation of ZnO-DMF dispersion containing nano-ZnO and polyvinylpyrrolidone

A new approach for fabricating polyethersulfone (PES)/ZnO ultrafiltration membrane is demonstrated. Nano-ZnO coated with polyvinylpyrrolidone (PVP) was prepared using dimethylformamide (DMF) as the solvent. The obtained ZnO-DMF dispersion was blended as an additive to fabricate PES/ZnO membranes with wet phase separation. The structure and performance of PES/ZnO membranes were characterized by the evaluation of surface pore size, porosity, water contact angle, pure water flux, BSA rejection and filtration resistance. The overall effect of ZnO-DMF dispersion addition on the structure and performance of the membrane was investigated by contrast with pure PES membrane. Compared with a pure PES membrane, PES/ZnO membranes have higher surface pore size, pore density and porosity, as well as improved surface hydrophilicity. The water fluxes of PES/ZnO membranes increased by approximately 210% compared with the pure PES membrane, with little change in BSA rejection. Besides, PES/ZnO membranes were also fabricated with different ZnO-DMF dispersions comprising a fixed content of PVP and different contents of nano-ZnO. The concrete contribution of nano-ZnO in ZnO-DMF dispersion on improving membrane performance was investigated by comparison with PES/PVP membrane. The results indicated that the incorporated nano-ZnO was favorable to the improvement of compaction resistance and antifouling property. The thermal stability of the PES/ZnO membranes was also improved compared to that of PES membrane.

Effects of in situ and ex situ formations of silica nanoparticles on polyethersulfone membranes

This study deals with the observed changes in the structure and performance of polyethersulfone (PES) membranes due to in situ formation and ex situ addition of silica particles (SiO2). Hydrolysis and condensation of tetraethyl orthosilicate (TEOS) inside the PES polymer matrix and the reaction of TEOS with ammonium hydroxide were chosen to form in situ and ex situ SiO2 formations, respectively. The resultant structure confirmed by X-ray diffraction for the composite PES membranes showed the retention of the amorphous nature even after the addition of SiO2. The FTIR study revealed the functional groups corresponding to silica networks with enhanced OH signatures on the surface of the composite membranes. Field emission scanning electron microscopic images showed the variation in the surface and cross-sectional structures for the pure and composite membranes. Considerable reduction in the thickness of the skin, difference in the pore structure and ‘finger-like’ cross-sectional morphology with the presence of SiO2 was observed in PES membranes. Both SiO2/PES composite membranes were showed a minor change in their glass transition temperature (Tg). The ex situ methodically formed composite membrane displayed an increase in the pure water flux and decrease in bovine serum albumin rejection as compared to in situ and pure PES membranes. These kinds of composite membranes can be utilized for water treatment applications demanding higher water flux.

Enhanced water flux in vertically aligned carbon nanotube arrays and polyethersulfone composite membranes

A vertically aligned carbon nanotube array structure enhances water flux in polyethersulfone ultra-filtration membranes.

Improving the antifouling property of polyethersulfone ultrafiltration membrane by incorporation of dextran grafted halloysite nanotubes

Polyethersulfone (PES) ultrafiltration membrane with improved antifouling property was prepared via traditional phase inversion method by incorporation of dextran grafted halloysite nanotubes (HNTs-Dextran). Fourier transforms infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM) results showed that HNTs were modified by dextran successfully. The hybrid membranes were characterized by contact angle, scanning electron microscopy (SEM), and cross-flow filtration and antifouling measurements. The results indicated that the surface hydrophilicity of membranes was significantly improved after adding HNTs-Dextran. Compared with the pure PES membranes, the hybrid membranes possess higher flux and good antifouling properties. In addition, the content of HNTs-Dextran in the hybrid membranes was an important factor affecting the morphology and separation properties of the membranes.

Preparation and antibacterial property of SiO2–Ag/PES hybrid ultrafiltration membranes

ABSTRACT Polyethersulfone (PES) ultrafiltration membranes with antibacterial property were prepared by blending with SiO2–Ag composites via immersion precipitation phase inversion method. In this study, silica sol was prepared by tetraethoxysilane via hydrolysis and polymerization, then silica was mixed with AgNO3 solution, and silver nanoparticles were deposited on the surface of SiO2 via reduction reaction. FTIR spectra results showed that silica sol was prepared successfully. SiO2–Ag composites were characterized by transmission electron microscopy (TEM). The hybrid membranes were characterized by permeation properties testing, scanning electron microscopy (SEM), and antibacterial activity analysis. The permeation properties testing indicated that the modified membranes had higher pure water flux than the pure PES membrane. SEM results showed that the structure of membrane was not obviously affected by addition of SiO2–Ag composites. The antibacterial effect of the SiO2–Ag/PES hybrid membrane was assayed with Escherichia coli and Staphylococcus aureus cultures and evaluated with the viable cell count method, and the antibacterial rates of the hybrid membranes against E. coli and S. aureus could reach 100%.

A comparison on gas separation between PES (polyethersulfone)/MMT (Na-montmorillonite) and PES/TiO2 mixed matrix membranes

Polyethersulfone (PES)-based mixed matrix membranes (MMMs) with the incorporation of inorganic fillers of different shapes (lamellar Na-montmorillonite (MMT) clays and spherical TiO2 nanoparticles) were prepared in this study, and the resulting MMMs were characterized by TGA, DSC, XRD, SEM, and TEM. It was found that inorganic filler agglomeration became more serious at higher-filler-content MMMs. In the case of PES/MMT MMMs, both the CO2 and CH4 permeabilities increased significantly with the increasing filler content and consequently the gas selectivity was greatly reduced. At high MMT loadings (⩾10 wt.%), Knudsen diffusion became the predominant gas transport mechanism. A different trend was achieved in the case of PES/TiO2 MMMs. The CO2/CH4 selectivity increased from 24.5 (pure PES membrane) to a maximum value of 38.5 at 4 wt.% TiO2 MMM and then decreased with a further increase in TiO2 content (e.g. 17.3 for 20 wt.%). The formation of interface voids and membrane defects in MMMs contributed to the high gas permeabilities and low gas selectivity.

Effect of silver loaded sodium zirconium phosphate (nanoAgZ) nanoparticles incorporation on PES membrane performance

Polyethersulfone (PES) based ultrafiltration membranes were fabricated via phase inversion by adding silver-loaded sodium zirconium phosphate nanoparticles (nanoAgZ) in PES casting solutions. The effect of nanoAgZ concentration on the membrane performance, i.e., morphology, hydrophilicity, thermal stability, permeation and antifouling properties was investigated. The results of thermal gravitational analysis (TGA) showed that the thermal stability of the hybrid membrane had been improved by the addition of nanoAgZ particles. Contact angle results indicated that the hydrophilicity of the modified membranes was enhanced. The contact angle of the membrane decreased from 71.5° to 52.6° with the increase of the nanoparticle content in the casting solution. Permeation experiment results showed that the modified PES membranes demonstrate better separation performance over the pure PES membrane. The pure water flux of PES membrane increased from 82.1 L/m 2 h to 100.6 L/m 2 h with the addition of the nanoparticles. Most importantly, the incorporation of the nanoAgZ particles enhanced the BSA fouling resistance and also the anti-biofouling performance of the membrane.

BSA-Modified Polyethersulfone Membrane: Preparation, Characterization and Biocompatibility

A polyethersulfone (PES) membrane was modified by blending with a co-polymer of acrylic acid (AA) and N-vinyl pyrrolidone (VP), followed by immobilization of bovine serum albumin (BSA) onto the surface. The scanning electron microscopy results showed that PES had good miscibility with the co-polymer. X-ray photoelectron spectroscopy confirmed the existence of P(VP-AA) co-polymer on the surface of the blended membrane and the existence of BSA after the immobilization process. The amount of BSA immobilized on the surface of the membranes was determined. It was found that the protein adsorption amounts from BSA, human plasma fibrinogen and diluted human plasma solutions decreased significantly after modification. According to the circular dichroism results, the proteins kept more α-helix conformation in the modified membranes than in the pure PES membrane. The number of the adhered platelets was reduced, and the morphology change for the adherent platelets was also suppressed by the modification with BSA. The SEM morphological observation of the cells and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay demonstrated that the BSA-modified PES membrane surface promoted endothelial cell adhesion and proliferation.

Amphiphilic graft copolymers based on ultrahigh molecular weight poly(styrene- alt-maleic anhydride) with poly(ethylene glycol) side chains for surface modification of polyethersulfone membranes

Amphiphilic graft copolymers having ultrahigh molecular weight poly(styrene- alt-maleic anhydride) (SMA) backbones and methoxyl poly(ethylene glycol) (MPEG) grafts were synthesized via the esterification between anhydride groups with hydroxyl groups. The synthesized graft copolymers, SMA- g-MPEGs, were used as additives in the preparation of polyethersulfone (PES) membranes via phase inversion process. X-ray photoelectron spectroscopy (XPS) analysis showed the comb-like graft copolymers spontaneously segregated to membrane surface during membrane formation. Water contact angle measurements and water absorbance experiments indicated the PES/SMA- g-MPEG blend membranes were much more hydrophilic than pure PES membrane. The blend membranes had stronger protein adsorption resistance than pure PES membrane did. After washed using de-ionized water for 25 days, the blend membranes exhibited higher hydrophilicity and stronger protein adsorption resistance. This phenomenon was attributed to the further accumulation of SMA- g-MPEG additives on membrane surface in aqueous conditions. SMA- g-MPEGs can be well preserved in membrane near-surface and not lost during membrane washing due to their high molecular weight and comb-like architecture.