Polyacrylonitrile Hollow Fiber Research Articles

Energy recovery and clean water remediation using antibiofouling polysaccharide coated PAN hollow fiber membrane obtained via green route synthesis

Biofouling is an important biological constrain in the water treatment process, and the control or management strategies using green principles have gained recent attention. Antibiofouling agents based on the biological source are now extensively studied due to their high efficacy and are environmentally friendly. In this present study, Poly Acrylo Nitrile (PAN)/Ulvan hollow fibre membranes of four different modules were fabricated for water treatment studies by testing against B. subtilis and E. coli along with separation efficiency studies on proteins such as albumin, pepsin, and clay. Ulvan (Ulv), green seaweed sulfated polysaccharide extracted from Ulva fasciata, was coated on PAN hollow fibres, fabricated using a wet-spinning process. Ulvan was dip-coated on membrane surface followed by cross-linking and resultant changes in terms of performance and morphology. PAN/Ulv hollow fibre membranes were examined for the pure water flux and protein separation analysis to analyse the membrane efficiency. SEM was used to analyse the membrane structure and ATR- FTIR for the determination of functional groups. Ulvan coated (310 C) hollow fibre membrane showed better performance than the other three membranes with a flux of 398.1 L m−2 h−1. Higher sample concentration of suspended solids paved simpler route for enhanced COD sequestration efficacy. Pepsin, albumin, and clay particles were rejected by the 310C Ulvan adorned membranes at rates greater than 80%. By incrementing suspended particles beyond 3200 mg/L, the greatest power recovery was reduced that portrays an adverse influence of bio-fouling process on membrane operation. Experimental results demonstrated that synthesised 310 C membrane possessed better separation performance and antifouling characteristics for aquatic water systems.

Separation and capture of CO2 from ambient air using TEPA-functionalized PAN hollow fibers

Solid amine sorbents have potential application in direct air capture of CO2 due to the advantages of low generation energy-demanding, and high adsorption capacity. Although the powdery solid amine sorbents exhibit high CO2 adsorption capacity, large pressure drop still limits their applicability. Structured solid amine are considered as good alternatives to solve this problem, but they still have the bottle-neck of insufficient CO2 adsorption capacity. To this end, we proposed solid amine hollow fiber to address these problems. In this work, tetraethylenepentamine (TEPA)-functionalized polyacrylonitrile (PAN) hollow fibers were fabricated via hydrolyzing nitrile groups on hollow fiber surface and then chemically grafting TEPA on it. The as-prepared PAN-TEPA hollow fiber was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET). In CO2 capture experiment, PAN-TEPA hollow fiber achieved high adsorption capacity under low CO2 concentration (5.07 mmol g−1, 5000 ppm, CO2-N2) source. The adsorption kinetics were studied, and Avrami fractional-order kinetics model fitted best with experimental curve. The adsorption capacities under low concentrations fitted well with Langmuir isotherm. Temperature-vacuum swing (TVS) desorption process was employed to rengenerate PAN-TEPA hollow fiber, and the regeneration conditions were screened. In direct air capture, PAN-TEPA hollow fibers had an adsorption capacity of 2.02 mmol g−1. CO2 Saturated PAN-TEPA hollow fibers could be efficiently regenerated by TVS desorption process. After 11 adsorption–desorption cyclic experiments, the decrease of breakthrough CO2 adsorption capacity is not obvious. Due to their characteristics in CO2 adsorption and desorption processes, PAN-TEPA hollow fiber is a potential sorbent for separation and capture of CO2 from ambient air.

Using Tannic-Acid-Based Complex to Modify Polyacrylonitrile Hollow Fiber Membrane for Efficient Oil-In-Water Separation

Separating oil from water allows us to reuse both fluids for various applications, leading to a more economical process. Membrane separation has been evidenced as a cost-effective process for wastewater treatment. A hollow fiber membrane made of polyacrylonitrile (PAN) is an excellent choice for separating oil from water because of its superior chemical resistance. Its low antifouling ability, however, reduces the effectiveness of its separation. Hence, in this study, we used tannic acid (TA) and FeIII complex to modify the surface of the PAN hollow fiber membrane. To improve membrane performance, different reaction times were investigated. The results demonstrate that even when the TA-FeIII covered the pores of the PAN membrane, the water flux remained constant. However, when an emulsion was fed to the feed solution, the flux increased from 50 to 66 LMH, indicating low oil adhesion on the surface of the modified membrane. When compared to the pristine membrane, the modified membrane had superior antifouling and reusability. As a result, the hydrophilic TA-FeIII complex on PAN surface improves overall membrane performance.

Preparation and properties of phosphinic acid-functionalized polyacrylonitrile hollow fiber membrane for heavy metal adsorption.

In this study, phosphorylated polyacrylonitrile hollow fiber membrane was synthesized by reacting aminated polyacrylonitrile hollow fiber membrane with phosphinic acid in a Mannich reaction. The batch single-factor measurements revealed that the phosphorylated polyacrylonitrile (PPAN) membrane had an outstanding ability for Hg2+ adsorption. Thermodynamic investigations indicated that the adsorption process was homogenous, and the theoretical maximum adsorption capacity predicted by the Langmuir model was 371.75mg·g-1. The PPAN membrane was able to successfully chelate Hg2+ ions and attain saturation in 4h, demonstrating that the reaction was chemically controlled by the adsorption kinetics. Based on the FT-IR and XPS spectral characterization data, successful phosphinic acid group grafting was proven, and a plausible mechanism for Hg2+ adsorption by PPAN membranes was presented. Furthermore, the five adsorption-desorption cycle experiments revealed that PPAN hollow fiber membranes had outstanding reusability, indicating a possible use for removing heavy metal ions from wastewater.

Investigating the Effects of Nonsolvent Additive and Spinning Conditions on Morphology and Permeation of PAN Hollow Fiber Membranes

In this study, polyacrylonitrile hollow fiber (PAN HF) membranes were designed and fabricated with desired morphology and permeability for low pressure-driven applications via the dry-wet phase-inversion spinning process. The effects of multiple design and fabrication parameters on permeation, morphology, thickness, and pore size of membranes were investigated using various techniques. Moreover, the effects of water as the nonsolvent additive, chemical composition of the bore solution, dope solution flow rate, air gap, coagulation bath temperature, and tensile ratio (take-up speed) were investigated. The addition of 3% wt. water as the nonsolvent additive into the dope solution resulted in a seventeen-times increment in the water flux up to 495 L m-2 h-1 bar-1. It showed a significant improvement in membrane porosity compared with those prepared without water nonsolvent additive. Utilization of 90% wt. of the solvent in water solution as the bore solution instead of pure water showed the most significant effect on the water flux and membrane structure among the fabrication parameters. It resulted in a reduction in threshold permeation pressure by more than ten times. The results revealed that whichever variation, including increased dope solution flow rate or coagulation bath temperature, or reduced air gap or traction, leads to promotion of membrane water flux. Still, different effects on the structure and morphology of the membranes were observed. Based on the outcomes of this study and according to the SEM images, one can conclude that outer surface pore size reduction from about 300 nm resulted in decreased water flux from 448 to 226 L m-2 h-1 bar-1, so that no pores were observed in the outer surface until 50 K magnification of the SEM image. The findings in this study provide instructive guidelines for the design and fabrication of high-performance hydrophilic PAN-based hollow fiber membranes with the desired morphology and water flux. Best ranges of investigated parameters for relatively high permeate water flux and desired membrane morphology were reported.

Direct capture of low concentration CO2 using tetraethylenepentamine-grafted polyacrylonitrile hollow fibers

This work demonstrated the fabrication of an efficient CO2 sorbent by grafting amines on the highly porous matrix of polyacrylonitrile (PAN) hollow fibers for CO2 capture from low concentration sources. Tetraethylenepentamine-grafted polyacrylonitrile (TEPA@PAN) hollow fibers were characterized by Fourier transform infrared spectroscopy (FT-IR), scan electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) methods. Their CO2 adsorption capacities at low concentrations (470–5000 ppm) were also investigated, indicating the values ranged from 1.70 to 3.66 mmol g−1. The CO2 adsorption capacities fitted well with Langmuir isotherm model. The adsorption kinetic study was performed by using two kinetic models, and pesudo-second model was found fitting better with experimental data. In consideration of their real applications to capture CO2 from confined space, TEPA@PAN hollow fibers were employed to adsorb CO2 directly from atmosphere (25 °C, 470 ppm, RH 25%), and their CO2 adsorption capacity reached up 2.03 mmol g−1. The used TEPA@PAN hollow fibers after CO2 adsorption can be regenerated by temperature swing process. 20 adsorption-desorption cyclic tests were carried out, and no obvious decrease in CO2 adsorption capacity was observed. Owing to their favorable characteristics for CO2 adsorption from low concentrations, TEPA@PAN hollow fiber may be a promising and cost effective sorbent for CO2 removal from confined space or ambient air.

Preparation and characterization of nanoclay loaded polyacrylonitrile hollow fiber membranes

New Polyacrylonitrile (PAN) nanoclay hollow fiber membranes were successfully fabricated through the dry-jet wet spinning process. The effects of adding the nanoclay on the hollow fiber mechanical properties and permeation performance and dye removal from water were investigated. Direct red 80, Direct orange 26 and Direct brown 2 dyes were used for dye removal experiments. Field emission scanning electron microscopy (FESEM) was used to analyze the cross-sectional and surface morphology and porosity. X-ray diffraction (XRD) has been used to compare crystalline structure of the fabricated hollow fiber membranes. The results showed that permeation is increased by adding nanoclay to the spinning dope. In addition, hollow fibers spun with lower nanoclay content showed lower hydraulic permeability and higher dye removal efficiency. Tensile strength increased from 1.09 to 2.06 with 3 wt% nanoclay loading.

Polyacrylonitrile homogeneous blend hollow fiber membrane with stable structure as a substrate to support Fe/Mn oxide and its enhanced capability to purify dye wastewater

Abstract Blending different molecular weight polyacrylonitrile (PAN) was adopted to solve the shrinkage problem of high molecular weight PAN hollow fiber membrane, to enhance the application performance of low molecular weight PAN membrane, and to adjust the porosity, pore size distribution, and hydrophilicity of the end product. The structurally-optimized membrane was chosen as a substrate to support Fe/Mn oxides and then used as a reactor to remove dyes from their solutions in the presence of H2O2. The results showed that the flux of methylene blue (MB) aqueous solution was 83.7 L/m2 h for the PAN homogeneous blend membrane, much higher than 29.1 L/m2 h of high molecular weight PAN membrane; MB removal efficiency was 97.3%, higher than 62.3% of low molecular weight PAN membrane, and it could be reused 25 times to remove dyes from their solutions without any loss in removal efficiency. The membrane was also found to have the application advantages of decreasing H2O2 dosage, reducing operation pressure, and raising MB removal efficiency compared with other membranes reported in the pieces of literature. Therefore, we were confident that the hollow fiber membrane fabricated by us would exhibit great application potential in the field of decontaminating dye wastewater.

One-step cross-linking and tannic acid modification of polyacrylonitrile hollow fibers for organic solvent nanofiltration

Simple and versatile modification techniques are highly sought after in the field of membrane science. However, common procedures such as interfacial polymerization require multiple solutions and several steps, particularly when dealing with hollow fiber membranes. In line with strategies laid out for fabricating greener membranes, we report a single-step cross-linking and modification process involving only an aqueous solution of the naturally-occurring tannic acid (TA) and hydrazine for polyacrylonitrile-based hollow fibers. Hydrazine plays a dual role of cross-linking the polyacrylonitrile while forming bonds with TA to yield a robust modification. By simply changing the amount of TA used, hollow fibers with different filtration properties can be obtained, as demonstrated by standard pore size tests using aqueous feeds. TA may even penetrate into the membrane bulk and further improve its mechanical properties. Solvent-related tests such as immersion tests and pure solvent permeation are first conducted for a preliminary understanding of membrane performance. To further demonstrate the efficacy of the one-step modification, organic solvent feeds, such as dyes dissolved in methanol, are employed in nanofiltration tests using these hollow fibers. Long-term tests reveal a stable methanol permeance of 1.2 L m-2 h-1 bar-1 and sustained 100% rejection of Evans Blue (Mw = 960.81 g mol-1). Thus, with each reagent playing several roles in this one-step process, a greener yet simple modification method is established for polyacrylonitrile-based membranes and materials.

Study on Graphene Oxide-Modified Polyacrylonitrile Hollow Fiber Membrane

In this paper, a multilayer diazo resin-graphene oxide/polyacrylonitrile composite membrane was prepared by layer-by-layer self-assembly and UV-induced modification of commercial polyacrylonitrile (PAN) hollow fiber membranes grafted with diazo resin (DR) and graphene oxide (GO). Scanning electron microscopy (SEM), infrared spectroscopy, contact angle, thermogravimetric analysis (TG), water flux and adsorption properties of heavy metals were studied. The results showed that diazo resin (DR) and graphene oxide (GO) were successfully grafted onto PAN membranes by layer-by-layer self-assembly. Carbonyl and carboxyl groups appeared on the surface of the modified PAN membranes; layer-by-layer self-assembly modification did not destroy the original morphology of PAN membranes, resulting in smaller pore size and higher surface roughness; hydrophilicity of the modified PAN-(DR-GO)3 membranes. The contact angle of pure water decreases from 87.8 degrees to 55.5 degrees, and the water flux increases from 733.30 g.m−1.h−1 to 1250.48 g.m−1.h−1. The thermo gravimetric curves of PAN films before and after modification did not change significantly, and the PAN films before and after modification had good thermal stability. The modified PAN membrane can achieve adsorption equilibrium in a relatively short time, and has good adsorption performance for heavy copper ions, with the adsorption rate as high as 92%.

Iron/manganese oxide-decorated GO-regulated highly porous polyacrylonitrile hollow fiber membrane and its excellent methylene blue-removing performance

Polyacrylonitrile (PAN) hollow fiber membrane wet-spun without any porogen usually has a wide pore size distribution, low porosity, and unstable porous structure. In this work, graphene oxide (GO) was selected as a structural optimizer to tune the porous structure of the PAN membrane. The results show that pore size and porosity increase from 156.4 nm and 37.0% to 590.8 nm and 81.4% as GO amount increases from 0 to 0.15%, which also causes a narrower pore size distribution. A simple and viable route of gradient hydrolysis, coordination, and oxidation was then adopted to decorate the PAN membrane with well-grown and well-dispersed iron/manganese oxide to achieve a functional membrane that could remove methylene blue (MB) from water stably and efficiently in the presence of H2O2. Compared with the membrane without GO, the functional membrane has a higher oxide decoration ratio, lower water contact angle, larger pores, higher porosity, and better mechanical property, and its MB solution flux is roughly two times higher than that of the membrane without GO. Additionally, the functional membrane can remove MB from the water after 30 cycles without any obvious efficiency attenuation; by contrast, MB removal efficiency induced by the membrane without GO attenuates remarkably after 25 cycles.

Separation of reactive dyes from textile effluent by hydrolyzed polyacrylonitrile hollow fiber ultrafiltration quantifying the transport of multicomponent species through charged membrane pores

A hydrolyzed polyacrylonitrile (PAN) based ultrafiltration grade hollow fiber membrane using sodium hydroxide having high surface potential was developed in this work. Efficacy of this membrane was demonstrated in treatment of textile effluent. Scanning electron microscopy (SEM) clearly showed that hydrolysis of PAN fibers (HPAN) made them dense. Fourier transform infrared (FTIR) spectra clearly indicated the functional groups confirming the hydrolysis of PAN matrix. The molecular weight cut-off of the HPAN fibers was reduced to 5 kDa from 20 kDa of untreated PAN lowering the average pore radius from 3.6 to 1.8 nm. A decline in the water contact angle of HPAN to 54° from 78° indicated the formation of a more hydrophilic membrane. The surface zeta potential of the hollow fiber was lowered to −12 mV from −2 mV imparting the negative potential on the membrane promoting charge-charge interaction between membrane pore and charged species during filtration. The surface roughness of the membrane was reduced almost by one order of magnitude after hydrolysis indicating its antifouling characteristics. The transport of the dyes and the electrolyte through the membrane pores was analyzed using Donnan steric pore model (DSPM) for a multicomponent system applicable for low cut off ultrafiltration. Contribution of various transport mechanisms, i.e., diffusion, convection and electro-migration was quantified. Thus, the novelty of this work includes (i) development of low cut off ultrafiltration grade hollow fibers; (ii) their application in treatment of real life effluent containing four reactive dyes; (iii) development of multicomponent pore transport model using DSPM.

Fe/Mn oxide decorated polyacrylonitrile hollow fiber membrane as heterogeneous Fenton reactor for methylene blue decolorization

ABSTRACTA very distinctive modification route was schemed to fabricate a membrane reactor that could heterogeneously catalyze Fenton reactions to decolorize dye wastewater in the process of filtration. Through this route, porogen‐free polyacrylonitrile (PAN) hollow fiber membrane was decorated with in situ generated well‐distributed Fe/Mn composite oxide, and the so‐called membrane reactor was finally acquired. Its performance of decolorizing dye wastewater was evaluated by feeding methylene blue (MB) aqueous solution into its lumen side and analyzing the permeate gained from its shell side. The results showed that about 97.4% of MB could be removed from its aqueous solution as the solution passed through the shell side of hollow fiber membrane, and this removal efficiency would keep unchanged when operation period was lengthened. The membrane reactor presented excellent capability to decolorize MB aqueous solution and could be used repeatedly without any loss in decolorization efficiency. Finally, the mechanism of causing MB decolorization was proposed by comparing decolorization performance of modified and unmodified membranes, measuring total organic carbon, and analyzing UV–Vis spectra. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48217.

The preparation of polyelectrolyte/hydrolyzed polyacrylonitrile composite hollow fiber membrane for pervaporation

Abstract In recent years, layer-by-layer self-assembly technology is one of the methods of preparing thin film composite membrane with ultra-thin selection layer. In this study, a single bilayer polyelectrolyte/hydrolyzed polyacrylonitrile (HPAN) hollow fiber membranes were fabricated by self-assembly technique for pervaporation. Branched polyethyleneimine (BPEI) and polyacrylic acid (PAA) were used as the cation polyelectrolyte and anion polyelectrolyte, respectively. Polycation/HPAN composite hollow fiber membranes were prepared by self-assembling BPEI onto the outer surface of HPAN hollow fiber membranes through electrostatic interaction. Subsequently, polycation/HPAN composite hollow fiber membranes were self-assembled with PAA to form polyanion/polycation/HPAN composite hollow fiber membranes. The effect of hydrolyzed and self-assembly on the property and pervaporation performances of aqueous ethanol solution through resulted hollow fiber membranes were investigated. By using the BPEI/PAA self-assembly, a single bilayer polyanion/polycation/HPAN composite hollow fiber membrane with excellent pervaporation performances was obtained. Furthermore, the effects of pervaporation conditions such as feed concentration, feed temperature, and downstream pressure on the pervaporation performances through BPEI/PAA/HPAN composite hollow fiber membranes were also investigated in this study.

Robust thin film composite PDMS/PAN hollow fiber membranes for water vapor removal from humid air and gases

Abstract Water vapor in humid air and industrial gases needs to be removed for various applications such as air conditioning, foodstuffs storage, aviation and space flights. Membranes can remove water vapor from gas streams without involving phase change and regeneration. A robust and productive membrane is vital for water vapor removal but it is challenging to produce it. Here we present a defect-free thin film composite (TFC) polydimethylsiloxane (PDMS)/polyacrylonitrile (PAN) hollow fiber membrane with an ultrathin PDMS selective layer of about 260 nm. Different from previous works, the PAN substrate was spun at a high take-up speed of 60 m/min. It has an average of surface pore size of 5.6 nm and superior mechanical properties. After the optimal PDMS coating, the composite membrane shows a N2 permeance of about 280 GPU, an O2/N2 selectivity of 2.2 and a water vapor permeance ranging from about 800 to 3700 GPU depending on operation conditions. In addition, the PDMS/PAN composite membrane has been tested for 48-hour outer door dehumidification and shown very stable and robust performance with a water vapor removal rate of 65% from the humid air. Besides, the PDMS/PAN composite membrane is not only able to efficiently dry the humid biogas but also upgrade its methane content simultaneously. Therefore, the newly developed TFC composite membrane has great potential for water vapor removal from humid air and various gas streams.

Preparation of polyamide/polyacrylonitrile composite hollow fiber membrane by synchronous procedure of spinning and interfacial polymerization

In this investigation, a new concept for fabrication polyamide (PA)/polyacrylonitrile (PAN) composite hollow fiber membrane by using a triple orifice spinneret was explored. Tetraethylenepentamine (TEPA) and trimesoyl chloride (TMC) were used as the monomers of aqueous solution and acid chloride solution, respectively. The PAN dope, TEPA solution and TMC solution were pumped into the outermost, middle and inner channel of the triple orifice spinneret, respectively, and then co-extruded into water from the outlet of the spinneret simultaneously. The PA layer then was formed on the lumen surface of the synchronous wet-spun PAN hollow fiber membrane. SiO2 was added into the dope to increase the hydrophilicity of the dope. The resultant PA/PAN composite hollow fibers were characterized by using FTIR-ATR, SEM, light transmission, contact angle and positron annihilation spectroscopy (PAS). The effects of SiO2 content, TEPA concentration, as well as the TEPA solution flow rate on the properties and pervaporation performances of resultant PA/PAN composite hollow fibers were investigated. The PA layer was completely attached to the lumen surface of the resulted hollow fibers through the spinning and interfacial polymerization synchronous procedure. The pervaporation performances with 419 g/m2h of permeation flux and 96.6 wt% of water content in permeate of the 90 wt% aqueous isopropanol solution at 25 °C can be obtained through the synchronous fabricated PA/PAN composite hollow fiber membrane which was fabricated by the 18 wt% PAN dope containing 5 wt% SiO2, 1 ml/min of 14 wt% TEPA solution and 2 ml/min of 1 wt% TMC solution.

Aluminium fumarate metal organic framework incorporated polyacrylonitrile hollow fiber membranes: Spinning, characterization and application in fluoride removal from groundwater

Novel mixed matrix hollow fiber membranes (MMM) were prepared by phase inversion technique using polyacrylonitrile (PAN) as base polymer and aluminium fumarate (AlFu) metal organic framework (MOF) as additive. The membranes were characterized in terms of surface morphology, surface charge, permeability, molecular weight cut off, porosity, pore size and contact angle. Permeability of the membrane increased from 3.5 × 10−10 to 4.5 × 10−10 m/Pa.s with increment of MOF concentration from 0 to 10 wt%. The contact angle of the corresponding membranes decreased from 80° to 51° indicating an increase in hydrophilicity. The MH10 (10 wt% concentration) membrane sustained up to 20, 19 and 17.5 h of operation with fluoride concentration of 4, 8 and 12 mg/l, respectively, at 35 kPa transmembrane pressure and 30 l/h cross flow rate with a membrane area of 0.026 m2. Regeneration study and performance of the MMM in real life ground water samples were also investigated. Filter performance was successfully predicted by a modified model available in literature.

From ultrafiltration to nanofiltration: Hydrazine cross-linked polyacrylonitrile hollow fiber membranes for organic solvent nanofiltration

Ultrafiltration-level polyacrylonitrile (PAN) hollow fiber membranes were molecularly engineered via chemical cross-linking to obtain membranes suitable for use in organic solvent nanofiltration (OSN). By adjusting the dope composition and spinning conditions, hollow fibers possessing a desirable sponge-like cross-section with minimal macrovoids were obtained. Hydrazine monohydrate was used as the cross-linker and the effects of cross-linking time on the membrane's separation performance were investigated. X-ray photoelectron spectroscopy was used to elucidate the possible reactions and indicated the successful cross-linking of the PAN hollow fiber membranes. The cross-linked nanofiltration-level hollow fibers were subjected to OSN tests using ethanol and dyes as model feed solutions. With this simple and effective modification, the PAN hollow fiber membranes were able to achieve a pure ethanol permeance of 2.32Lm−2 h−1bar−1 and an impressive Remazol Brilliant Blue R (Mw 626.54gmol−1) rejection of more than 99.9%. Given the ease of fabrication and modification, these PAN hollow fibers represent a significant step forward in the use of hollow fiber membranes for OSN, particularly in larger-scale operations.

Preparation and performance of biofouling resistant PAN/chitosan hollow fiber membranes.

The preparation of polyacrylonitrile (PAN) hollow fiber (HF) membranes has been carried out by dry-jet wet spinning. PAN HF membranes were coated with chitosan biopolymers 2 wt% by dip coating and further crosslinked by chemical reagents (Tri sodium polyphosphate). PAN HF (Virgin) and PAN/chitosan coated membrane were characterized by SEM and tested for water flux. Proteins Pepsin, Albumin, and Clay of 1000ppm concentration were tested for separation efficiency. In addition, bacterial speciesEscherichia coliandBacillus subtiliswere tested for fouling control efficiency and found out that PAN/chitosan membranes were quite superior to virgin PAN fibers.The adhesion of bacterial cells on the surface of the hollow fiber membranes assessed through alcian blue staining and SEM analysis. It was observed that PAN/chitosan membranes (310A and 310C) possessed best antibacterial activities (based on SEM results), qualifying them as a very promising candidates for anti-biofouling coatings.

The preparation of polyamide/polyacrylonitrile thin film composite hollow fiber membranes for dehydration of ethanol mixtures

Abstract In this study, Polyamide (PA)/polyacrylonitrile (PAN) thin-film composite (TFC) hollow fiber membranes were fabricated to investigate the dehydration performances of ethanol mixtures by pervaporation. Amine monomers (ethylenediamine (EDA), 1, 6-hexanediamine (HDA), diethylenetriamine (DETA), and tetraethylenepentamine (TEPA)) with difference number of functional groups or chain length were selected to react with trimesoyl chloride (TMC) to prepare a PA dense thin-film onto the surface of asymmetric PAN hollow fiber membranes by way of interfacial polymerization. Attenuated total reflection infrared spectroscopy (FTIR-ATR), scanning electron microscope (SEM), atomic force microscope (AFM), light transmission, contact angle and positron annihilation spectroscopy (PAS) were used to characterize the physicochemical properties, morphologies and microstructure of the PA thin layer. The pervaporation performances of aqueous ethanol solution showed the permeation flux decreased while water content in permeate increased with increasing number of amine groups. The effects of monomer concentration and reaction time on the pervaporation performances of aqueous ethanol solution through TEPA-TMC/PAN TFC hollow fiber membranes were also investigated. A 342.0 ± 22.3 g/m 2 h permeation flux and 97.6 ± 0.3 wt.% water content in permeate were obtained for the pervaporation of 90 wt.% aqueous ethanol solution at 25 °C through the PA/PAN TFC hollow fiber membrane which was fabricated by immersing PAN hollow fiber membrane into 2 wt.% TEPA aqueous solution for 1 min and then contacting 1 wt.% TMC solution for 0.5 min.