Polyacrylonitrile Hollow Fiber Research Articles

Interaction of arbekacin with dialysis membrane

The interaction between arbekacin and the hemodialysis membrane is unclear. The aim of this study was to evaluate the adsorption of arbekacin (ABK) onto hemodialysis membranes and to establish a simpler system for evaluating the adsorption properties of the drug. First, small cut pieces of polysulfone or sulfonated polyacrylonitrile (AN69) hollow fiber membranes were stirred in a solution of ABK for the qualitative assessment. Then, we designed the experimental system that was approximately 1/100 of the actual size using a small dialyzer “mini-module” of our original design for the polysulfone or AN69. We circulated ABK solution in this system for the quantitative assessment. Finally, we administered ABK in subjects undergoing hemodialysis as a clinical trial to evaluate the adsorption of ABK onto polysulfone or AN69. In the qualitative assessment, the rates of ABK adsorption onto polysulfone and AN69 were 6.2 ± 2.9 and 49.8 ± 1.8 %, respectively. In the quantitative assessment, although there was almost no change in the circulating ABK concentration with the use of polysulfone, there was about 68 % decrease in the circulating ABK concentration with the use of AN69. In the clinical trial, clearance by the dialyzer using AN69 was high at 10 min after starting dialysis, despite the sieving coefficient being 0. However, reduction of ABK clearance was observed with time; the removal rate of ABK at the completion of the dialysis using polysulfone or AN69 was about 67 %, with no difference between the two membranes. The main limitation of this study was the small sample size in the clinical trial. These findings suggest that ABK is adsorbed onto AN69. Furthermore, the present adsorption experiment with a mini-module was considered useful as an evaluation system because it was easy to handle, using less solvent and drugs compared with a previous report, and it reflected the results of the clinical trial.

Neuronal membrane bioreactor as a tool for testing crocin neuroprotective effect in Alzheimer’s disease

In this paper a neuronal membrane bioreactor was developed as platform for the in vitro reconstruction of a neuronal network with defined functional, geometric and neuroanatomical features. The bioreactor consists of modified polyacrylonitrile hollow fiber membranes that were assembled in parallel in order to establish two separate compartments: an intraluminal compartment within the fibers, in which the medium flowed, and an extraluminal compartment or shell outside of the fibers where cells were cultured. We explored the ability of the membrane bioreactor to promote the growth and functional differentiation of neuronal cells up to 2weeks.Neuronal cells in the bioreactor covered completely the fiber surface and exhibited a high density of the axonal network reaching a very complex 3D structural organization characterized by the expression of presynaptic vesicle protein synaptophysin. Cells were also functionally active as demonstrated by the oxygen uptake rate and glucose consumption that increased with culture time achieving values of 17.7nmol/min and 879±113nmol/min at day 15, respectively.The neuronal membrane bioreactor was used as in vitro model of Aβ-induced toxicity associated to Alzheimer’s disease to test for the first time in cells the neuroprotective effect of crocin. The administration of the Aβ produced a dramatic decrease of cell viability and induced the reactive oxidative species (ROS) generation and apoptosis. When Aβ-peptide was administered together with crocin a significant dose-dependent inhibition of apoptosis and ROS production was observed pointing out the capability of crocin to prevent the aggregation of Aβ peptide and subsequent neurotoxicity associated to Alzheimer’s disease.

Fabrication of polyacrylonitrile hollow fiber membranes from ionic liquid solutions

PAN hollow fiber membranes with good pore morphology have been fabricated using solvent mixtures of ionic liquids and DMSO, which has a lower toxicity than other commonly used polar organic solvents.

Polyacrylonitrile supported thin film composite hollow fiber membranes for forward osmosis

Thin film composite (TFC) hollow fiber membranes have shown great promise as a platform for osmotic processes such as forward osmosis (FO) and pressure retarded osmosis (PRO). Previous work on asymmetric FO membranes demonstrated that employing a hydrophilic supporting structure is essential to promote wetting and mitigate concentration polarization. In this study, we have developed an intrinsically hydrophilic polyacrylonitrile (PAN) hollow fiber supported TFC membrane. A selective polyamide thin film was synthesized on the membrane shell side via interfacial polymerization. The impact of fiber pore structure was investigated during our study with some of our membranes exhibiting water flux of 36.6Lm−2h−1 using 1M sodium chloride draw solution against deionized water in PRO mode. These results suggest the potential of utilizing intrinsically hydrophilic polymeric hollow fibers with finely tuned pore structures as support for TFC membranes for osmotic processes.

Improving antifouling performance of PAN hollow fiber membrane using surface modification method

In this study, a new approach to improve antifouling performance of polyacrylonitrile (PAN) hollow fiber membrane has been explained. Firstly, chemical modification with sodium hydroxide (NaOH) solution was performed on PAN membranes in various conditions, so that, as a result of hydrolysis, carboxyl groups emerge on membrane surface. Then, in order to improve surface hydrophilicity, the hydrolyzed membrane underwent a polyethylene glycol (PEG) deposition through a chemical reaction. Chemical changes in membrane were characterized via Fourier transform infrared spectroscopy/attenuated total reflectance (FTIR/ATR). In addition, measurement of contact angle and fouling test were performed to analyze hydrophilicity degree and performance of modified membrane, respectively. Results of measuring contact angle signified improvement of hydrophilicity of membrane after modification. Modified membranes showed lower tendency to foul during ultrafiltration (UF) of milk solution, which is confirmed by increase in flux recovery ratio (FRR) level following membrane modification. Three hours after hydrolysis process, though pure water flux through membrane reduced by 28% comparing with intact membrane, the level of polyvinyl alcohol (PVA-30 kDa) rejection and FRR increased 13 and 14%, respectively. Upon attachment of PEG to the membrane surface, the contact angle reduced from 64° for non-modified membrane to 21°.

Surface modification of PAN hollow fiber membrane by chemical reaction

In this study, a new method was applied to achieve an efficient surface modification of Polyacrylonitrile (PAN) hollow fiber membrane. The surface modification dealt by immersion of PAN hollow fibers in hydroxylamine solution under various conditions (different solution concentrations and reaction time). The nitrile groups on the surface of the membrane were changed to form the amidoxime (-C(NH2)=N-OH) groups. The surface modified membranes were assessed by pure water permeation test and the rejection of high molecular weight materials like Polyvinylalcohol (PVA) from water. Permeation test results showed that with increasing hydroxylamine concentration, the amount of water permeation reduces slowly, while the PVA-30 kDa rejection has been somewhat increased after surface modification. FTIR/ATR analysis confirms the presence of amidoxime groups on the membrane surface. Also, the water contact angel was decreased from 64 to 34 after reaction. The ability of silver ions absorption was also assessed for modified membrane. Finally, the antifouling property of the modified hollow fibers was assessed by milk solution ultrafiltration. The obtained results showed that the modified hollow fibers present better antifouling properties.

Pebax®/PAN hollow fiber membranes for CO2/CH4 separation

Poly(ether-b-amide) (Pebax®1657)/polyacrylonitrile (PAN) composite hollow fiber membranes for a potential use in CO2/CH4 separation were prepared by a new continuous coating method, referred to as cross-flow filtration. This technique allows to obtain the simultaneous coating of a large number of fibers, facilitating the scale-up. The dense layer was deposited in the lumen of the fibers allowing the coating of all the fibers in a single step. The coating on the inner surface of the fibers avoids the negative effects such as sticking or accidental mechanical damages occurring in the case of external coating. The membrane preparation was optimized by modulating different parameters. The optimal range of viscosity and concentration of the polymer solution to obtain a selective homogeneous Pebax® layer was identified. The presence of the Pebax®1657 dense layer was confirmed by IR spectroscopy and the morphology of the composite membranes was observed by SEM analysis. The gas separation performance of the membrane modules was determined by single gas permeation measurements. A preliminary optimization yielded membranes with PCO2=5×10−3 (m3m−2h−1bar−1), αCO2/CH4=18 equal to that of the neat dense polymer. The PEBAX®/PAN hollow fibers modules are potentially useful for application in the purification of biogas.

Preparation and characterization of braided tube reinforced polyacrylonitrile hollow fiber membranes

ABSTRACTPolyacrylonitrile (PAN) and polyester (PET) braided hollow tube that used as a special reinforcement are braided from their filaments via two‐dimensional weaving techniques. PAN braided tube reinforced homogeneous PAN hollow fiber membranes and PET braided tube reinforced heterogeneous PAN hollow fiber membranes are prepared by concentric circles squeezed‐coated spinning method. As for PAN hollow fiber membrane, the effects of PAN concentration on the performance of the prepared hollow fiber membranes are investigated in terms of pure water flux, protein rejection, mechanical strength, and morphology observations by a scanning electron microscope (SEM). The interfacial bonding state of the braided tube reinforced PAN hollow fiber membranes is studied by constant speed stretching method. Results show that the breaking strength of two‐dimensional braided tube reinforced PAN hollow fiber membranes is higher than 80 MPa. The structure of separation surface is similar to the structure of an asymmetric membrane. With the increase of polymer concentration, the membrane flux decreases while the retention rate of BSA increase. The membrane porosity and maximum pore size have the same decreasing tendency as the increase of PAN concentration. The results also show that the interfacial bonding state of the PAN two‐dimensional braided tube reinforced homogeneous PAN hollow fiber membranes is better than that of the PET two‐dimensional braided tube reinforced heterogeneous PAN hollow fiber membranes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41795.

Determination of surface potential of hollow fiber membranes by streaming potential method

Streaming potential method at tangential flow of solution has been proposed as a means of measuring the surface potential of hollow fiber membranes. Zeta potential and surface charge for polyacrylonitrile hollow fiber nanofiltration membranes have been measured. The measurements have been made on the membranes of different porosities obtained by partial drying of initially wet membranes. Porosity has been evaluted from the rate of pressure-driven filtration of a solution through membrane pores. An equation has been derived that allows for assessment of the effect of solution flow in the porous layer. It has been shown that more correct values of membrane surface potential can be calculated using this equation.

Layer-by-layer (LbL) polyelectrolyte membrane with Nexar™ polymer as a polyanion for pervaporation dehydration of ethanol

Novel LbL polyelectrolyte multilayer membrane (PEMM) with Nexar™ polymer, a sulfonated pentablock copolymer, as the polyanion on a hydrolyzed polyacrylonitrile (PAN) hollow fiber substrate has been developed for pervaporation dehydration of ethanol. The advantages of applying the sulfonated copolymer as the polyanion are that the required bi-layer numbers can be significantly reduced while achieving a good separation performance. With just one bi-layer of polyethyleneimine (PEI) polycation and Nexar™ polyanion, the newly developed PEMM shows a flux of 1160g/m2h and a separation factor of 127 at 50°C for ethanol dehydration. The PEMM exhibits good stability up to a 170-h continuous operation with a flux decline at the initial stage because of substrate densification. This study demonstrates the possibility of employing the sulfonated pentablock copolymer as a polyanion for PEMMs to dehydrate biofuel via pervaporation.

Performance assessment and hydrodynamic analysis of a submerged membrane bioreactor for treating dairy industrial effluent

Submerged membrane bioreactor (SMBR) is a relatively advanced technology for waste water treatment that involves integrated aerobic and anaerobic biological processes with membrane filtration. In the present investigation, hydrophobic polyvinylidene fluoride (PVDF) and hydrophilic polyacrylonitrile (PAN) hollow fiber (HF) membranes were tested in an indigenously fabricated SMBR for dairy effluent treatment under aerobic conditions using mixed microbial consortia. Effect of operating parameters such as suction pressure, degree of aeration and trans-membrane pressure (TMP) on membrane performance in terms of flux, rejection of turbidity, BOD and COD besides fouling characteristics was investigated. The observed optimum permeabilities of PVDF and PAN HF membranes were approximately 108 and 115LMHbar−1 with high extent of impurity removal. The rejection of COD was found to be 93% for PVDF and 91% for PAN HF membranes whereas corresponding rejection of BOD was observed to be 92% and 86%. A two-dimensional comprehensive model was developed to predict the hydrodynamic profile inside the module. Regression analysis revealed that the simulation results agreed well with experimental data.

A Recipe Research of PAN Hollow Fiber Ultrafiltration Membranes

Polyacrylonitrile (PAN) hollow fiber ultrafiltration (UF) membranes were prepared via wet spinning method using lithium chloride (LiCl) and calcium chloride (CaCl2) as pore-foaming agent. Influences of PAN, LiCl and CaCl2 contents to water flux, rejection rate, breaking strength and breaking elongation of the membrane were discussed. Results indicated that the comprehensive performance of the membrane was the best when the PAN/LiCl and PAN/CaCl2 ratios in the spinning solution equaled to 18:1.

Fouling behaviors of polybenzimidazole (PBI)–polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) hollow fiber membranes for engineering osmosis processes

This paper investigated the individual effects of reverse salt flux and permeate flux on fouling behaviors of as-spun and annealed polybenzimidazole (PBI)–polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) hollow fiber membranes under forward osmosis (FO) and pressure retarded osmosis (PRO) processes. Two types of membrane fouling had been studied; namely, inorganic fouling (CaSO4·2H2O gypsum scaling) during FO operations and organic fouling (sodium alginate fouling) during PRO operations. It is found that gypsum scaling on the membrane surface may be inhibited and even eliminated with an increase in reverse MgCl2 flux due to competitive formations of MgSO4° and CaSO4·2H2O. In contrast, the increase of reverse NaCl flux exhibits a slight enhancement on alginate fouling in both FO and PRO processes. Comparing to the reverse salt flux, the permeate flux always plays a dominant role in fouling. Therefore, lesser fouling has been observed on the membrane surface under the pressurized PRO process than FO process because the reduced initial flux mitigates the fouling phenomena more significantly than the enhancement caused by an increase in reverse NaCl flux.

Study on the interfacial bonding state and fouling phenomena of polyvinylidene fluoride matrix-reinforced hollow fiber membranes during microfiltration

Reinforced polyvinylidene fluoride (PVDF) and polyacrylonitrile (PAN) hollow fiber membranes were prepared through dry–wet spinning process and included PVDF or PAN polymer solutions (coating layer) and matrix PVDF membrane. The performance of the membranes varies with different polymer solutions and is characterized in terms of ink solution and activated sludge flux, dynamic mechanical analysis (DMA), mean pore size, a mechanical strength test, and morphology observations by a scanning electron microscope (SEM). The results of this study indicate that PAN coating layer is easy to peel off from the matrix membrane. Interfacial bonding strength is also detected by dynamic mechanical analysis indirectly. The reinforced membranes show a narrower pore size distribution and smaller mean pore size than the matrix membrane. The elongation at break increases much more and the membranes are endowed with better flexibility performance. The homogeneous-reinforced (HMR) and heterogeneous-reinforced (HTR) membranes have a lower rate of flux decline compared with matrix membrane during ink solution filtration. The main types of all membranes fouling in microfiltration of ink solution were attributed to initial pore blocking followed by cake formation. Then, in the activated sludge solution, the reinforced membranes have stable efficiency in antifouling property for the real MBR system.

The Preparation of Polyamide/Polyacrylonitrile Composite Hollow Fiber Membranes for Pervaporation

This paper prepared polyamide (PA)/polyacrylonitrile (PAN) thin-film composite hollow fiber membranes via interfacial polymerization by using triethylenetetramine (TETA) and trimesoyl chloride (TMC) as the monomers and asymmetric PAN hollow fiber membrane as the substrate. The effect of hydrolysis of asymmetric PAN hollow fiber membranes on the chemical properties was investigated. The results showed that the chemical properties of PAN hollow fiber membranes were affected by hydrolysis. Moreover, the effects of PA thin film polymerized onto the inner and outer surface of asymmetric PAN hollow fiber membranes on pervaporation performances were also investigated. The results also revealed that the interfacial polymerized PA/PAN composite hollow fiber membranes that were polymerized onto the outer surface of asymmetric PAN hollow fiber membranes can be used in the pervaporation of aqueous alcohol solution.

Heat-Treated Polyacrylonitrile (PAN) Hollow Fiber Structured Packings in Isopropanol (IPA)/Water Distillation with Improved Thermal and Chemical Stability

In this study, polyacrylonitrile (PAN) hollow fiber membrane (HFM) was heat-treated by muffle furnace to strengthen the thermal and chemical stability. Membrane morphology with different materials was characterized by scanning electron microscopy (SEM). It has shown that both porosity and pore size decreased with increasing heat treatment time (t = 0.5, 6, 12 h) and temperature (T = 200, 250, 300, and 350 °C). FTIR was used to explore the change of chemical bonds and found that dehydrogenation, cyclization, and cross-linking reactions occurred in thermal treatment. Compared with original PAN membrane, the hydrophobicity of heat-treated membranes was obviously improved. The heat-treated membrane PAN-250-6 (PAN–temperature–duration) was selected and immersed in various boiling solvents for 24 h to test material stability. PAN-250-6 membrane presented excellent thermal and chemical stability especially in strong solvent, N,N-dimethylacetamide (166.1 °C), whereas original PAN membrane was dissolved completely...

Fouling-resistant membranes for the treatment of flowback water from hydraulic shale fracturing: A pilot study

Polyacrylonitrile hollow fiber ultrafiltration (UF) and polyamide spiral wound reverse osmosis (RO) membrane modules were surface-modified by contact with an aqueous solution containing dopamine to deposit polydopamine on the membrane surfaces and other wetted parts inside the modules. UF modules were further modified by grafting poly(ethylene glycol) (PEG) brushes to the polydopamine coating. Polydopamine and polydopamine-g-PEG coatings increase hydrophilicity of the membrane surfaces and have previously been shown to improve fouling resistance towards model oil/water emulsions in laboratory studies. In a pilot-scale test treating hydraulic fracturing flowback water from the Barnett Shale region of Texas, the fouling performance of modified UF and RO membrane modules was compared to that of unmodified analogs. UF modules were used to remove most of the highly fouling organic matter in the feed before desalination by a train of RO elements. Polydopamine-modified UF modules maintained higher flux, lower transmembrane pressure difference, and improved cleaning efficiency relative to unmodified modules. The polydopamine coating did not appear to improve RO fouling behavior, presumably because most of the organic foulants had been removed by UF pretreatment of the feedwater. However, higher and more stable salt rejection was observed in modified RO modules than in unmodified modules.

Fabrication of PAN Hollow Fiber Ultrafiltration Membrane with Salt Porogen

Polyacrylonitrile (PAN) hollow fiber ultrafiltration membranes were prepared by wet spinning method using lithium chloride (LiCl) or calcium chloride (CaCl2) as porogen and dimethyl formamide (DMF) as solvent. The effects of PAN/LiCl and PAN/CaCl2 ratios in the spinning solution on the permeation properties of the formed membranes were studied.

Novel Nanofiltration Hollow Fiber Membrane Produced via Electrospinning

Submicrometer polyacrylonitrile (PAN) hollow fiber membranes were fabricated via concentric electrospinning and were assembled into a filtration module. The module operated in an “inside-out” mode where a feed solution is introduced through the lumen while filtrate is collected from outside the fiber wall through a side arm. The relatively smooth PAN fibers exhibited 530 and 890 nm average inner and outer diameters, respectively. The performance of the hollow fibers was tested by filtering an Indigo carmine dye and NaCl solutions. The dye solution passed through the PAN fibers, and the filtrate was colorless indicating that water but not dye permeates through the fiber walls. In a similar fashion, the NaCl solution was desalinated with 97.7% ± 0.6 salt rejection.

The effects of substrate characteristics and pre-wetting agents on PAN–PDMS composite hollow fiber membranes for CO2/N2 and O2/N2 separation

In order to develop high performance poly(dimethylsiloxane)-polyacrylonitrile (PDMS/PAN) hollow fiber composite membranes for the separation of CO2/N2 and O2/N2 gas pairs, we have investigated: (1) the viscosity of PDMS solutions as a function of curing conditions; (2) pore size and pore size distribution of the PAN substrates as a function of spinning conditions and post-treatments and (3) the effects of pre-wetting agents, substrate morphology and PDMS concentration on the gas performance of the selective layer. Based on their complicated relationship, fundamental science and engineering have been elucidated to fabricate PDMS/PAN hollow fiber composite membranes with CO2, N2 and O2 permeances of 3700, 370 and 860GPU and selectivities of 10 and 2.2 for CO2/N2 and O2/N2 gas pairs at 25°C and 2atm, respectively. This O2/N2 separation performance is comparable with the best ever reported results for O2 enrichment. The PAN hollow fibers were prepared by a dry-jet wet spinning process and subsequently coated with PDMS by dip-coating. To increase gas permeance, experimental results show that, in addition to keeping substrate pores open, partially crosslinking PDMS and pre-wetting the PAN substrates by Fluorinert 72 (FC-72) or deionized water before dip coating in order to prevent intrusion are important. This study may provide insights and guidelines to fabricate highly permeable membranes in the industry for O2 enrichment, flue gas separation and CO2 capture.