Hollow Fiber Ultrafiltration Membranes from Poly(Vinyl Chloride): Preparation, Morphologies, and Properties (original) (raw)
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Journal of Applied Polymer Science, 2012
Poly(vinyl chloride) (PVC) hollow-fiber membranes were spun by a dry/wet phase-inversion technique from dopes containing 15 wt % PVC to achieve membranes with different pore sizes for ultrafiltration (UF) applications. The effects of the N,N-dimethylacetamide (DMAc) concentration in the internal coagulant on the structural morphology, separation performance, and mechanical properties of the produced PVC hollow fibers were investigated. The PVC membranes were characterized by scanning electron microscopy, average pore size, pore size distribution, void volume fraction measurements, and solubility parameter difference. Moreover, the UF experiments were conducted with pure water and aqueous solutions of poly(vinyl pyrrolidone) as feeds. The mechanical properties of the PVC hollow-fiber membranes were discussed in terms of the tensile strength and Young's modulus. It was found that the PVC membrane morphology changed from thin, fingerlike macrovoids at the inner edge to fully spongelike structure with DMAc concentration in the internal coagulant. The effective pores showed a wide distribution, between 0.2 and 1.1 lm, for the membranes prepared with H 2 O as the internal coagulant and a narrow distribution, between 0.114 and 0.135 lm, with 50 wt % DMAc. The results illustrate that the difference in the membrane performances was dependent on the DMAc concentration.
Hollow fiber ultrafiltration membranes prepared from blends of poly (vinyl chloride) and polystyrene
Desalination, 2012
Polymeric blend ultrafiltration membranes based on poly(vinyl chloride) (PVC) and polystyrene (PSR) were prepared by phase inversion method. The PSR concentration in dope solution varied from 1 to 6 wt.%. DMAC was used as a solvent, while water was used as internal and external coagulant. Scanning electron microscope (SEM) was utilized to characterize cross-section, outer, and inner surfaces of the hollow fiber structure. Differential scanning calorimetry (DSC) was used for the determination of the glass transition temperature (Tg) of the blends. From the experimental results it was found that, the structural morphology of the polymeric blend varied with the PSR concentration. There is no significant decrease in pure water permeation flux by using 1 and 2 wt.% PSR concentration in dope solution. The PVP K-90 rejection highly improved from 76.2% to 98.53% with the addition of 1 wt.% PSR concentration. The PVC/PSR blends show incompatibility by the results of SEM and DSC. Also it was found that the mechanical properties of PVC/PSR blend membranes were improved randomly compared with that of PVC membrane.
Desalination, 2002
Hollow-fiber membranes were prepared by the dry/wet spinning technique from polyvinylidene fluoride (PVDF) dope solutions containing the solvent N, N-dimethylacetamide and the non-solvent additive 1,2-ethanediol. Ethanol aqueous solution, 50% by volume, was used as internal and external coagulants. The effect of the non-solvent additive concentration on the morphological properties of the hollow fibers was studied in terms of atomic force microscopy (AFM) and scanning electron microscopy (SEM). The pore size, the nodule size and the roughness parameters at the inner and outer surfaces of the hollow fibers were studied by AFM. The liquid entry pressure of water (LEPw) and the porosity of the hollow fibers were evaluated. The pore size was also determined by the gas permeation test and by the solute transport using ultrafiltration of polyethylene glycol (PEG) and polyethylene oxides (PEO). A comparative study was made between the membrane characteristics parameters obtained from the different characterization techniques.
A study on the performance and morphology of multicomponents hollow fiber ultrafiltration membrane
(Polysulfone/poly(vinylpyrolidone)-K30/N,N-dimethylacetamide) hollow fiber ultrafiltration membrane was spun using dry-wet spinning method. The membrane was produced at different shear rate. Permeation properties and separation tests were examined using pure water flux and sodium chloride solution of concentration 1g/L respectively. Membrane morphology and molecular orientation were observed and directly measured using scanning electron microscopy (SEM) and plan polarized infrared spectroscopy. Positive infrared dichroism was detected only in samples of highest shear membranes. This suggests that the polymer molecules become aligned under high shear. Permeation test using pure water showed that increasing shear rate increases flux. On contrary, percentage rejection using sodium chloride solution showed a decreasing trend in rejection with the increased in shear rate. Increasing shear rate during dope extrusion through spinneret in the spinning of hollow fiber ultrafiltration membranes will apparently decrease the skin layer thickness and thus increasing the flux and also enhances the molecular orientation in the skin layer which causes high percentage rejection which was in the range of 21% to 33% for transmembrane pressure of 6 bar. The results indicate that there is a strong correlation between extrusion shear rate and the membrane morphology thus affecting the flux and rejection of hollow fiber ultrafiltration membranes.
Membranes
In this work, PPSUs with different molecular weights were synthesized for the development of highly permeable ultrafiltration hollow fiber membranes for the first time. The MW of the synthesized polymers was controlled by varying the monomers molar ratio within 1:1–1.15 under the same synthesis conditions. Based on the study of the rheological properties of polymer solutions, a high molecular weight PPSU (MW = 102,000 g/mol) was chosen for the formation of hollow fiber membranes. The addition of PEG400 to the spinning solution led to an increase in viscosity, which makes it possible to work in the region of lower PPSU concentrations (18–20 wt. %) and to form membranes with a less dense porous structure. With the addition of PEG400 to the spinning solution, the membrane permeance increased sharply by more than two orders of magnitude (from 0.2 to 96 L/m2·h bar). At the same time, the membranes had high rejection coefficients (99.9%) of Blue Dextran model filtered substance (MW = 69,0...
Preparation of PVC Hollow Fiber Membrane Using (Dmac/Acetone)
Journal of Chemical and Petroleum Engineering, 2014
Membrane manufacturing system was operated using dry/wet phase inversion process. A sample of hollow fiber membrane was prepared using (17% wt PVC) polyvinyl chloride as membrane material and N, N Dimethylacetamide (DMAC) as solvent in the first run and the second run was made using (DMAC/Acetone) of ratio 3.4 w/w. Scanning electron microscope (SEM) was used to predict the structure and dimensions of hollow fiber membranes prepared. The ultrafiltration experiments were performed using soluble polymeric solute poly ethylene glycol (PEG) of molecular weight (20000 Dalton) 800 ppm solution 25 °C temperature and 1 bar pressure. The experimental results show that pure water permeation increased from 25.7 to 32.2 (L/m 2 .h.bar) by adding acetone to the dope solution, while rejection decreased from 91.8 to 63.2%.
ACS Omega, 2018
Poly(vinyl chloride) (PVC)/SiO 2 nanocomposite hollow-fiber membranes with different nano-SiO 2 particle loadings (0−5 wt %) were fabricated using the dry-jet wetspinning technique. Effects of SiO 2 nanoparticles on the morphology of the prepared hollow-fiber membranes were investigated using scanning electron microscopy. Transport and antifouling properties of the fabricated membranes were evaluated by conducting pure-water permeation, solute rejection, and fouling resistance experiments. These studies indicated that incorporating silica nanoparticles into the PVC matrix during phase inversion lowers the hydraulic resistance through the membrane and narrows the selective membrane pores. Moreover, the nanocomposite membranes showed better antifouling properties compared to the pristine membrane during the ultrafiltration of a milk solution because of improved hydrophilicity and uniform dispersion of the nanoparticles. This work indicates that embedding silica nanoparticles into the PVC matrix is a promising method for producing cost-effective hollow-fiber ultrafiltration membranes with superior transport and antifouling properties.
Journal of Chemical and Petroleum Engineering, 2010
Two different polyvinyl alcohol/polyvinyl chloride (PVA/PVC) hollow fiber composite nanofiltration membranes were prepared after PVC hollow fiber membranes were coated using dip-coating method with PVA aqueous solution, which was composed of PVA, fatty alcohol polyoxyethylene ether (AEO9), and water [PVA/AEO9/water (4:0.5:95.5) wt%]. Effect of two different PVC hollow fiber immersion times in coating solution were studied. Cross-section, internal and external surfaces of the PVC hollow fibers and PVA/PVC composite nanofiltration membranes structures were characterized by scanning electron microscopy (SEM), pure water permeation flux and solutes rejection. It was found that, the coating layer thickness on the outer surface of the 19 wt% PVC hollow fiber was thin and about (6μm), while the coating solution penetrates through the outer edge of the PVC hollow fiber and it looks like sponge-like structure with increase of the dip-coating time from 20 to 30 sec. Besides, the pure water pe...
Separation and Purification Technology, 2006
The objective of this study is to determine the effects of dope extrusion rate (DER) on polyethersulfone hollow fiber ultrafiltration membrane performance and morphology. The hollow fiber ultrafiltration membranes were produced by using a simple dry/wet spinning process with forced convection in the dry air gap. A newly developed dope solution consists of 20.6 wt.% polyethersulfone (PES), 63.6 wt.% 1methyl-2-pyrrolidone (NMP), 9.3 wt.% polyethylene glycol (PEG) and a mixture of potassium acetate and water (20/80 wt.%) was used as a bore fluid in this study. This newly developed dope solution was designed to be very close to its cloud point (binodal line) in order to speed up the coagulation process so that the relaxation effect on molecular orientation can be reduced. The dope extrusion rate was varied from 2.0 to 4.0 cm 3 /min with 0.5 cm 3 /min increments in order to study the effect of DER on fiber performance and morphology. The experimental results showed that the flux of the hollow fiber ultrafiltration membranes decreases while the separation performance for particular solute increases with an increase in dope extrusion rate. This suggests that the outer skin layer of the membranes becomes apparently thicker and denser with increasing dope extrusion rate. Once the separation performance reaches maximum (critical point), the rejection decreases with increasing dope extrusion rate, observed possibly due to formation of less tighten outer skin structure at high dope extrusion rate. Plane-polarized Fourier transform infrared spectroscopy revealed that membrane spun at dope extrusion rate of 3.5 cm 3 /min showed largest spectrum difference suggesting that higher molecular orientation is responsible for an enhanced separation performance. This study also indicated that ultrafiltration hollow fiber membrane produced has a high potential to be used for cyclodextrin separation.
Malaysian Journal of Fundamental and Applied Sciences
Asymmetric, porous ultrafiltration polysulfone (PSf) hollow fiber membranes were fabricated via the dry-wet phase inversion spinning technique specifically for haemodialysis membrane. The objective was to discover the suitable spinning condition for the fabrication of ultrafiltration hollow fiber membrane with desired sponge-like structure. During haemodialysis procedure, uremic toxins such as urea and creatinine range from size 10,000-55,000 Da needs to be excreted out from the blood. While, proteins such as albumin (66,000 Da) need to be retained. The physical structure or morphology of a fabricated membrane is a major concern in determining the efficiency of a dialysis membrane. Different type of membrane morphology will give a different result in term of its permeability and clearance efficiency. The phase inversion spinning technique is suitable in producing ultrafiltation (UF) membrane where the average pore size of the fabricated membrane is in the range of 0.001 – 0.1 µm. Ho...