• Membrane and Water Treatment
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• v.6 no.1
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• pp.1-13
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• 2015

The modification of ultrafiltration membranes with carbon nanotube (CNT) buckypaper on fouling control was investigated. Two types of commercially available flat-sheet membranes were used: PS35 and PES900C/D (PES) (the PS35 membranes were hydrophilic with a molecular weight cutoff of 20 kDa, and the PES membranes were hydrophobic with a molecular weight cutoff of 20 kDa). The CNT buckypaper modified ultrafiltration membranes were prepared by filtering a CNT suspension through the flat-sheet membrane in a dead-end ultrafiltration unit. After modification, the pure water flux of PES was significantly increased, while the pure water flux of PS35 was decreased. The properties of the CNT modified membranes were also investigated. Considering the antifouling properties, pure water flux of the modified membrane, and the stability of CNT buckypaper layer on the membrane surface, ethanol solution with a concentration of 50 wt.%, multi-walled carbon nanotubes (MWCNTs) with a larger diameter (30-50 nm), and the CNT loading with $7.5g/m^2$ was selected. The CNT buckypaper on the surface of ultrafiltration membranes can trap the pollutants in sewage effluent and prevent them reaching the surface of virgin membranes. Water quality analysis showed that the effluent quality of the modified membrane was obviously improved. The removal efficiency of humic acid and protein-like matters by the modified membrane was significant. These results indicate the potential application of the CNT buckypaper layer modified membranes in the field of wastewater reclaim.

• Membrane Journal
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• v.20 no.1
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• pp.76-86
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• 2010

This study investigated the effect of 2-butoxyethanol (BE) as a nonsolvent additive, relative humidity and air contact time on the structure formation of microfiltration membranes, permeation and morphology properties in phase inversion process. The membranes were prepared by using polyethersulfone (PES)/Dimethyl formamide (DMF)/p-toluenesulfonic acid (TSA)/Polyvinylpyrrolidone (PVP)/BE casting solution and water coagulant. Casting solutions containing various concentration of BE were exposed to a water vapor, under 60 and 80% of relative humidity for 40 and 90 sec, which would be absorbed on. The correlations between the membrane permeation properties and surface/inner structures of membrane were investigated. The characterization of membranes was carried out by a capillary flow porometer, a FE-SEM and a water permeation test apparatus. The surface structure of PES membranes was affected by the exposure time as well as the relative humidity strongly. Furthermore, the addition of BE helped control surface and inner structure at certain humidity and exposure time.

• Applied Chemistry for Engineering
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• v.16 no.1
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• pp.144-149
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• 2005

Sulfonated poly(ether ether ketone) (SPEEK) was blended with poly(ether sulfone) (PES) at various compositions. To investigate the possibility of using the blend membranes as polymer electrolyte membranes for direct methanol fuel cell, the blend membranes were characterized in terms of methanol permeability, proton conductivity, ion exchange capacity, and water content. Both proton conductivity and methanol permeability of SPEEK were relatively high. As the amount of PES increased, methanol permeability decreased more rapidly compared to proton conductivity. The experimental results indicated that the blend membrane with 40 wt% PES was the best choice in terms of the ratio of proton conductivity to methanol permeability.

• Macromolecular Research
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• v.9 no.5
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• pp.285-291
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• 2001

The polysulfone(PSf)/polyethersulfone(PES) blend membranes were prepared by an immersion precipitation method. N-methyl-2-pyrrolidone(NMP) was used as a solvent and water as a nonsolvent. The composition of the coagulation bath and the dope polymer concentration as well as the blend ratio of two polymers were varied. The membrane morphologies were interpreted on the basis of the phase diagram of the PSf/PES/NMP/water system. As the solvent content in the coagulation bath increased in the single polymer system, the number of macrovoids decreased and the morphology was changed from finger-like to cellular structure. In the given bath condition phase separation occurs earlier for the solutions of PSf/PES blend than for those of single polymer. A horizontally layered structure and horizontal protuberances inside the macrovoid were observed for the membranes formed from PSf/PES blend solutions. This peculiar structure formation can be interpreted by a PSf-rich/PES-rich phase separation followed by a polymer-rich/polymer-lean phase separation during the exchange of solvent and nonsolvent.

• Membrane and Water Treatment
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• v.8 no.1
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• pp.51-71
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• 2017

Antimicrobial polyethersulfone ultrafiltration membranes containing zerovalent iron ($Fe^0$) and magnetite ($Fe_3O_4$) nanoparticles were synthesized via phase inversion method using polyethersulfone (PES) as membrane material and nano-iron as nanoparticle materials. Zerovalent iron nanoparticles (nZVI) were prepared by the reduction of iron ions with borohydride applying an inert atmosphere by using $N_2$ gases. The magnetite nanoparticles (nMag) were prepared via co-precipitation method by adding a base to an aqueous mixture of $Fe^{3+}$ and $Fe^{2+}$ salts. The synthesized nanoparticles were characterized by scanning electron microscopy, X-ray powder diffraction, and dynamic light scattering analysis. Moreover, the properties of the synthesized membranes were characterized by scanning electron microscopy energy dispersive X-ray spectroscopy and atomic force microscopy. The PES membranes containing the nZVI or nMag were examined for antimicrobial characteristics. Moreover, amount of iron run away from the PES composite membranes during the dead-end filtration were tested. The results showed that the permeation flux of the composite membranes was higher than the pristine PES membrane. The membranes containing nano-iron showed good antibacterial activity against gram-negative bacteria (Escherichia coli). The composite membranes can be successfully used for the domestic wastewater filtration to reduce membrane biofouling.

• Membrane Journal
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• v.17 no.3
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• pp.219-232
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• 2007

The polyethersulfone(PES)-titanium oxide($TiO_2$) hybrid membranes were prepared by immersion precipitation phase inversion method. The casting solution for the preparation of $PES-TiO_2$ hybrid membrane was provided by adding $TiO_2$ nano particles into the basis polymer solution of 14 wt% and 20 wt% PES/N-methyl-2-pyrrolidone(NMP). The $TiO_2$ loading [wt% ($TiO_2/NMP$)] in eating solution was varied from 0 to 60 wt%. Membrane performance and morphological change of the resulting $PES-TiO_2$ hybrid membranes were discussed in aspect of $TiO_2$ loading, by viscosity, coagulation value and light transmittance of the casting solution, measurement of tensile strength, pore size and contact angle, surface and cross sectional SEM images of the hybrid membrane, and ultrafiltration experiments using the hybrid membrane. According as increase of $TiO_2$ loading in the casting solution, viscosity is increased and coagulation value becomes lower, therefore the thermodynamic instability of the casting solution is increased. It is found that when $TiO_2$ loading is increased, 1) precipitation rate becomes faster while instantaneous demixing is maintained, 2) pure water flux, membrane pore size and compaction stability of the resulting membranes are increased, 3) tensile strength and contact angle are decreased. Dead-end ultrafiltration of bovine serum albumin(BSA) solution using the hybrid membrane shows that membrane performance(flux of BSA solution) enhanced up to 7 times compared with the results obtained using the pure PES membrane(not containing $TiO_2$ particle), due to the increase of hydrophilicity.

• Membrane Journal
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• v.33 no.4
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• pp.191-200
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• 2023

Polyethersulfone (PES) is a widely employed membrane material for water and industrial purification applications owing to its hydrophilicity and ease of phase separation. However, PES membranes and filters prepared using the nonsolvent induced phase separation method often encounter significant flux decline due to pore clogging and cake layer formation on the dense membrane surfaces. Our investigation revealed that tight microfiltration or loose ultrafiltration membranes can be subject to physical fouling due to the formation of a dense skin layer on the bottom side caused by water intrusion to the gap between the shrank membrane and the substrate. To investigate the effect of the bottom surface porosity on membrane fouling, two membranes with the same selective layers but different sub-layer structures were prepared using single and double layer casting methods, respectively. The double layered PES membrane with highly porous bottom surface showed high flux and physical fouling tolerance compared to the pristine single layer membrane. This study highlights the importance of physical optimization of the membrane structure to prevent membrane fouling.

• Textile Coloration and Finishing
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• v.15 no.2
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• pp.68-75
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• 2003

In this work, ultrafiltration(UF) membranes were prepared using polyethersulfone(PES). The polymer was dissolved in various solvent, such as N, N-dimethyl formamide(DMF), N,-dimethyl acetamide (DMAc), N,N-dimethyl sulfoxide(DMSO) and N-methyl-2- pynolidone(NMP). Each polymer solution was casted on the glass plate, and immersed into non-solvent bath. In this way finely porous UF membranes were prepared by phase inversion method. The cross sectional structure of PES membrane was asymmetric which was consist of sponge-like sublayer, finger-like toplayer, and active skin layer. From the solute rejection experiments, the molecular weight cut off of the prepared membrane in various solvent was evaluated 10,000 for DMF, 30,000 for DMAc, 50,000 for DMSO, and 10,000 for NMP respectively.

• Membrane and Water Treatment
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• v.6 no.4
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• pp.323-337
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• 2015

Membrane Fouling was considered as major drawback in various industrial applications. Thus, this paper reviews the surface modification of polyethersulfone (PES) membranes for antifouling performance. Various modification techniques clearly indicate that hydrophilicity has to improve on the PES membrane surface. Moreover, the mechanism of fouling reduction with corresponds to various modification methods is widely discussed. Incorporation of hydrophilic functional groups on PES membrane surface enhances the surface free energy thereby which reduces the fouling. Characterization techniques adopted for the surface modified membranes was also discussed. These studies might be useful for the other researchers to utilize the modification technique for the applications of waste water treatment, chemical process industry and food industry.

• Membrane Journal
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• v.16 no.4
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• pp.303-312
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• 2006

The asymmetric hybrid membranes of polyethersulfone (PES) and $ZrO_2$ nanoparticles were prepared via new one-step procedure combining simultaneously the phase-inversion method and the sol-gel technique. The optimum contents of $Zr(PrO)_4\;and\;HNO_3$ catalyst were determined by the adsorption experiments of phosphate anion onto the resulting hybrid membranes. The maximum adsorption of phosphate anion is obtained at the conditions of 0.15 mL $Zr(PrO)_4$ addition per 1 mL PES and 30 mL $HNO_3$ addition per 1 mL $Zr(PrO)_4$. Variation of morphology, performance and incorporated $ZrO_2$ amount of the resulting hybrid membranes were discussed and determined using SEM, pure water flux, TGA, ICP, XRD and contact angle measurements. Increasing $Zr(PrO)_4$ addition into casting solution, pure water flux is increased and $ZrO_2$ amount in the hybrid membrane is maximized at the conditions 0.15 mL $Zr(PrO)_4$ addition per 1 mL PES. The prephosphatation of PES-$ZrO_2$ hybrid membrane was studied to modify the surface characteristics of membrane. Ultrafiltration of bovine serum albumin (BSA) solution was performed in a dead-end cell using both a bare (non-phosphated) and a phosphated hybrid membrane. It is revealed that both the permeate flux and BSA rejection were increased as about 40% by prephosphatation of hybrid membrane. These results may be explained on the basis of the increase of membrane hydrophilicity, which was determined from contact angle measurements.