Polymeric Hollow Fiber Membranes Research Articles

Recent 10-year development on surface modification of polymeric hollow fiber membranes via surface coating approach for gas separation: a review

Recent 10-year development on surface modification of polymeric hollow fiber membranes via surface coating approach for gas separation: a review

Polymeric hollow fiber membrane for cooling crystallization seeding: On the mechanism of induced nucleation based on thermal transfer

Cooling crystallization is an important separation process and particuology technology that requires accurate nucleation control strategies. Herein, we introduced the polymeric hollow fiber membrane with proper thermal properties as the effective nucleation induction interface during cooling crystallization. The heterogeneous nucleation control mechanism was introduced based on classical nucleation theory and the thermal transfer process. Interfacial properties and the thermal conductivity of two kinds of polymeric membranes, polytetrafluoroethylene (PTFE) and polyethersulfone (PES), were measured and simulated with the developed model. These two membranes possessed different nucleation induction periods, nucleation rates and crystallization performances, which validated that the hollow fiber membrane module could effectively accelerate the nucleation process compared to conventional cooling crystallization owing to the shorter nucleation induction period and the reduced solution surface tension. Due to the higher hydrophobicity and the lower roughness of the membrane surface, the PTFE membrane possessed a more moderate performance in generating stable heterogeneous nucleation than the one of PES membrane. Thus, the adjustable membrane property enabled the hollow fiber membrane-assisted cooling crystallization to possess the accurate nucleation control and desired terminal particle products.

Modification of PVDF hollow fiber membrane with ZnO structure via hydrothermal for enhanced antifouling property in membrane distillation

This study aims to provide a close insight into the possibilities and constraints associated with the development of ZnO structures on polyvinylidene fluoride (PVDF) hollow fiber membranes using the hydrothermal method to enhance membrane surface roughness for improved fouling resistance in membrane distillation (MD). Due to the flexible nature of polymeric hollow fiber membranes, there is a considerable risk of the ZnO structure detaching from the membrane surface when the membrane is bent. To address this issue, the hydrothermal duration was varied between 4 and 16 h to optimize the ZnO structure for high integrity, followed by fluorination. The results reveal that the membrane treated with hydrothermal for 8 h exhibits stable coating integrity, imparting the membrane with the highest contact angles with various liquids. This membrane demonstrates a flux of 4.0 kg/m2h and excellent salt rejection (>99.9 %) in direct contact MD (DCMD) when treating a 35 g/L saline solution. Additionally, the membrane exhibits outstanding antifouling performance with minimal flux reduction over 24 h when treating a saline solution containing humic acid. However, the upscaling of the hydrothermal approach may pose challenges due to the difficulty in maintaining the consistency of ZnO structure formation.

Fabrication of high-flux defect-free hollow fiber membranes derived from a phenolphthalein-based copolyimide for gas separation

In the realm of gas purifications, hollow fiber membranes have gained significant prominence due to their unique advantages. However, achieving defect-free membranes poses a considerable challenge. In this study, we addressed this challenge with a novel copolymer, 6FDA-DAM:DAP(2:1), comprising 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 2,4.6-Trimethy-m-phenylenediamine (DAM), and a phenolphthalein-derived diamine of 3,3′-diaminophenolphthalein (DAP). We found that defect-free hollow fiber membranes could be prepared when 20 wt% or more ethanol was added in the polymer dope solution, but this led to the formation of oval hollow fibers that would be flattened under high pressure. We solved this limitation by lowering ethanol content to 15 wt%, adding 2 wt% LiNO3, and increasing the air–gap distance. These measures reduced the difference in phase inversion rates between the surface region and the bulk phase of the nascent hollow fiber. The CO2 permeance of this defect-free hollow fiber membrane reached 282 GPU with a CO2/CH4 selectivity of 50.2. Highly permeable defective hollow fiber membranes were also developed using a polymer dope without LiNO3 and a low THF content of 5 wt%. After coated by silicone rubber, CO2 permeance of the membrane reached 554 GPU with a CO2/CH4 selectivity of 45.0. In mixed gas tests, the two membranes exhibited O2 permeances of approximately 43.3 and 75.3 GPU, with O2/N2 selectivities of 5.5 and 5.4, respectively. Their CO2 permeances were 281 and 465 GPU, with CO2/CH4 selectivities of 45 and 41, CO2/N2 selectivities of 35.7 and 33.3, respectively. These separation performances were among the best of state-of-art polymeric hollow fiber membranes and demonstrated great potential for gas separation applications such as natural gas sweetening, flue gas treatment, and air separation.

A new dip-coating approach for plasticization-resistant polyimide hollow fiber membranes: In situ thermal imidization and cross-linking of polyamic acid

Polymeric hollow fiber membranes (HFMs) are in high demand for gas separation due to their superior processability and cost-effectiveness, despite exhibiting high vulnerability to plasticization. In this study, we present a new dip-coating technique for fabricating defect-free and plasticization-resistant polyimide HFMs on a cross-linked polyimide/polysilsesquioxane hollow fiber support. This is achieved through an in situ process involving thermal imidization and cross-linking of a polyamic acid (PAA) precursor solution. The use of a thermally stable cross-linked nanoporous hollow fiber support ensures the coating of various glassy PAA solutions prepared by different dianhydrides and diamine monomers without disturbing its internal pore structure. The resulting polyimide hollow fiber membranes enhanced CO2/CH4 separation performance compared to as-synthesized polyimide solution-coated counterpart. It is because in situ thermal imidization and cross-linking of PAA solutions induced the formation of more imine linkages, possibly generating larger free volume elements due to the disturbance of intersegmental chain packing while maintaining sufficient chain rigidity. Additionally, the membrane’s practical applicability was confirmed as the hollow fibers demonstrated resistance to plasticization when subjected to an equimolar CO2/CH4 mixed feed of approximately 50 bar. Our simple but versatile dip-coating approach allows for the formation of highly plasticization-resistant polyimide HFMs.

Green chemistry-based fabrication of hollow fiber and flat sheet polyimide membranes for CO2/CH4 separation

In this work, the successful fabrication of polymeric hollow fiber (HF) and flat sheet (FS) membranes was examined by employing γ-butyrolactone (GBL)-a green and environmentally friendly solvent- for the polymer's dissolution following the principles of green chemistry and sustainability regarding the membrane preparation. In addition, the ternary phase diagram of the P84/GBL/water was constructed and the viscosity of dope solution was measured for different concentrations and temperatures. Their morphological characteristics of the prepared polyimide membranes were investigated through SEM analysis. CO2/CH4 separation measurements under continuous flow were performed to evaluate the efficiency of the membranes for a binary 10/90 vol.% CO2/CH4 gas mixture. The developed green HF and FS membranes exhibited comparable, and in some cases even superior, performance compared to membranes prepared using the conventional and highly toxic NMP solvent, making them highly promising candidates for CO2/CH4 separation, with a real mixture separation factor of ∼58.

Performance evaluation of novel ml-scale microbial fuel cells using different polymeric hollow-fiber membranes

A novel-designed milliliter-scale MFC was fabricated using three different polymeric hollow fiber membranes of Polyethersulfone (PES), Polyacrilonitryl (PAN), and Polyvinyldenfluoride (PVDF). PES, with a maximum power density of 629 mW/m2, a current density of 1333 mA/m2, and a coulombic efficiency (CE) of 4.22 %, achieved the best performance among the others. After that, the PAN membrane gained power and current densities of 450 mW/m2 and 847 mA/m2, and the PVDF membrane obtained the lowest power and current density of 63 mW/m2 and 187 mA/m2. For all the MFCs, the ohmic resistance incorporates only 2.5 to 5 % of internal resistance due to the small thickness of hollow fibers and the short distance between the electrodes. In the case of the PES membrane, the presence of the sulfonic group resulted in superior proton conductivity (128.10 ± 0.37 mS/cm) and reduced ohmic resistance (24.86 ± 0.07 Ω) compared to the others. Moreover, the charge transfer impedances of both electrodes for PES were nearly half of the values for PAN and about one-fifth of the values for PVDF. The increased electrical double layer capacitance nearby the electrodes of PES reveals more convenient growth of anodic exo-electrogenic bacteria and better accomplishment of cathodic reaction for this membrane. The COD removal efficiencies of 11.48 %, 10.55 %, and 6.48 % have been attained for PES, PAN, and PVDF, respectively.

A New Approach to the Development of Hollow Fiber Membrane Modules for Water Treatment: Mixed Polymer Matrices.

In this study, mixed matrix hollow fiber polymeric membranes were prepared using polyethersulfone (PES) and polyvinylidene fluoride (PVDF) as polymers in their composition. N-methyl-2-pyrrolidone (NMP) was used as a solvent and demineralized water with an electrical conductivity below 3 μS·cm-1 was used as a non-solvent. A new approach to producing enhanced polymeric hollow fiber membranes based on the preparation of a simple blend PVDF/PES solution, and on the conformation of the composite membranes through the extrusion technique followed by the phase inversion process in a non-solvent bath, was applied. The investigation focused on the preparation of polymeric membranes with different polymer ratios and further assessment of the effects of these proportions on the membrane performance and in specific physical properties. The amount of PVDF ranged from 10 to 90% with 10% steps. The presence of PVDF, although it increased the membranes' plasticity, had a negative effect on the overall mechanical properties of the composite membranes. Scanning electron microscopy (SEM) results showed good dispersion of both polymers in the polymeric matrix. Furthermore, the membrane permeability showed a slight negative correlation with contact angle, suggesting that membrane hydrophilicity played an important role in membrane permeability. Finally, it was found that membranes with low ratios of PVDF/PES may have potential for water treatment applications, due to the combined advantageous properties of PES and PVDF.

Copolyimide asymmetric hollow fiber membranes for high‐pressure natural gas purification

AbstractThe current process to purify contaminated natural gas reserves employs a highly energy‐intensive amine scrubbing technology. To satisfy the growing demand for natural gas coupled with the tight regulations on CO2 emissions, researchers worldwide are investigating the use of polymeric membranes for acid gas removal from natural gas streams, to reduce the energy consumption and carbon emission of the nowadays used technology. Placing a polymeric membrane unit at the upstream of the amine scrubbing column reduces the energy consumption during the regeneration process of saturated amines. Hence, the preparation of polymeric membranes in form of hollow fibers is a key step towards their industrial implementation for natural gas processing. The following study demonstrates the potential separation performance of 6FDA‐Durene/6FDA‐CARDO (5000:5000) in an integrally skinned defect‐free asymmetric hollow fiber geometry. The initial screening studies of the membrane shows good pure‐gas performance as it exhibits CO2/CH4 selectivity coefficients around 28 and CO2 permeance between 310 and 350 GPU. Feed pressures of up to 900 psig and stage cuts ranging from 5% to 20% were tested for a quaternary sweet mixed‐gas feed to assess the membrane performance under operating conditions that mimic those in industrial settings. Mixed‐gas permeance of all gases, and CO2/CH4 selectivity remain somewhat constant as the feed pressure increases up to 900 psig. Both mixed‐gas CO2 permeance and CO2/CH4 selectivity decline as the stage cut increases. As expected, as CO2 recovery is maximized, CO2 purity is minimized and CH4 loss increases with increasing stage cut. As a result of the trade‐off between recovery and purity, the data and analyses reported herein can provide insights into the limitations that certain operating parameters can pose on CO2 separation performance with similar polymeric hollow fiber membranes.

Strong degradation of polycarbonate and polystyrene by the CO2 capture solvent diethyl sebacate

AbstractWe report on observations of strong degradation of a polycarbonate vessel by a solvent being considered for a CO2 capture process, diethyl sebacate. This degradation led to failure of a polymeric hollow fiber membrane unit. Additional tests showed rapid degradation of polycarbonate safety glasses and polystyrene‐based petri dishes by exposure to diethyl sebacate at ambient conditions. We also report on safe operations with diethyl sebacate in extensive experiments studying the corrosion of steel in CO2‐pressurized reactors lined with PTFE and using PTFE gaskets. Used diethyl sebacate was also stored for long time periods in bottles made from low‐density polyethylene bottles without physical deterioration. These observations indicate that care must be taken in development of new contactors and processes for CO2 capture with diethyl sebacate and related solvents and in the choice of material for storage.

Preliminary study on ZIF-8 containing hollow fiber mixed matrix membranes (HFMMMs) for CO2 and CH4 gas permeation

The advantages in terms of smaller footprint, higher energy efficiency, larger surface-to-volume ratio and higher flux have opened various opportunities for hollow fiber membranes in separation processes especially in carbon dioxide (CO2) capture. Although the development of polymeric hollow fiber membrane has emerged as an important material in membrane technology, currently existing polymeric materials suffer from a limiting trade-off between selectivity and permeability. Recently, it has been reported in the literature that the addition of metal–organic frameworks into polymer matrixes have radically improved the separation performance of CO2 from methane (CH4), as well as enhanced the thermal stability and structural properties of the membrane. In this preliminary study, ZIF-8/cellulose triacetate hollow fiber mixed matrix membranes are fabricated by varying the air gap distances and subsequently, the morphology of the resultant membranes was analysed using a scanning electron microscope while the dispersion of ZIF-8 fillers in the polymer matrix was observed using an energy dispersive X-ray. The results showed that the ZIF-8 fillers were homogeneously distributed into the cellulose triacetate polymer. Then, the performance of the resultant membranes before and after post-treatment with polydimethylsiloxane in CO2 and CH4 gases permeation were evaluated. Due to the presence of multiple defects, the overall performance of the fabricated membranes was low with no significant improvements after post-treatment. Hence, further optimization study on the fabrication process is still required to improve the performance of the ZIF-8/cellulose triacetate hollow fiber mixed matrix membrane in CO2 and CH4 gas permeation.

On the quest of reliable 3D dynamic in vitro blood-brain barrier models using polymer hollow fiber membranes: Pitfalls, progress, and future perspectives.

With the increasing concern of neurodegenerative diseases, the development of new therapies and effective pharmaceuticals targeted to central nervous system (CNS) illnesses is crucial for ensuring social and economic sustainability in an ageing world. Unfortunately, many promising treatments at the initial stages of the pharmaceutical development process, that is at the in vitro screening stages, do not finally show the expected results at the clinical level due to their inability to cross the human blood-brain barrier (BBB), highlighting the inefficiency of in vitro BBB models to recapitulate the real functionality of the human BBB. In the last decades research has focused on the development of in vitro BBB models from basic 2D monolayer cultures to 3D cell co-cultures employing different system configurations. Particularly, the use of polymeric hollow fiber membranes (HFs) as scaffolds plays a key role in perfusing 3D dynamic in vitro BBB (DIV-BBB) models. Their incorporation into a perfusion bioreactor system may potentially enhance the vascularization and oxygenation of 3D cell cultures improving cell communication and the exchange of nutrients and metabolites through the microporous membranes. The quest for developing a benchmark 3D dynamic in vitro blood brain barrier model requires the critical assessment of the different aspects that limits the technology. This article will focus on identifying the advantages and main limitations of the HFs in terms of polymer materials, microscopic porous morphology, and other practical issues that play an important role to adequately mimic the physiological environment and recapitulate BBB architecture. Based on this study, we consider that future strategic advances of this technology to become fully implemented as a gold standard DIV-BBB model will require the exploration of novel polymers and/or composite materials, and the optimization of the morphology of the membranes towards thinner HFs (<50μm) with higher porosities and surface pore sizes of 1-2µm to facilitate the intercommunication via regulatory factors between the cell co-culture models of the BBB.

Modeling and Simulation of the Impact of Feed Gas Perturbation on CO2 Removal in a Polymeric Hollow Fiber Membrane.

A membrane contactor is a device that attains the transfer of gas/liquid or liquid/liquid mass without dispersion of one phase within another. Membrane contactor modules generally provide 30 times more surface area than can be achieved in traditional gas absorption towers and 500 times what can be obtained in liquid/liquid extraction columns. By contrast, membrane contactor design has limitations, as the presence of the membrane adds additional resistance to mass transfer compared with conventional solvent absorption systems. Increasing mass transfer in the gas and solvent phase boundary layers is necessary to reduce additional resistance. This study aims to increase the mass transfer in the gas phase layer without interfering with membrane structure by oscillating the velocity of the feed gas. Therefore, an unsteady state mathematical model was improved to consider feed gas oscillation. The model equation was solved using Comsol Multiphysics version 6.0. The simulation results reveal that the maximum CO2 removal rate was about 30% without oscillation, and at an oscillation frequency of 0.05 Hz, the CO2 percent removal was almost doubled.

Compaction of a Polymeric Membrane in Ultra-Low-Pressure Water Filtration.

Applications of ultra-low-pressure filtration systems are increasing as they offer enhanced sustainability due to lower energy input, almost no use of chemicals, and minimum operational expenditure. In many cases, they operate as a decentralized system using a gravity-driven membrane (GDM) filtration process. These applications are relatively new; hence, the fundamental knowledge of the process is still limited. In this study, we investigated the phenomenon of polymeric membrane compaction under an ultra-low-pressure system. The compaction phenomenon is well-recognized in the traditional pressure-driven system operating at high transmembrane pressures (ΔPs > 200 kPa), but it is less documented in ultra-low-pressure systems (ΔP < 10 kPa). A simple GDM filtration setup operated under a constant-pressure system was employed to investigate the compaction phenomena in a polymeric hollow fiber membrane for clean water filtration. Firstly, a short-term pressure stepping test was performed to investigate the occurrence of instantaneous compaction in the ΔP range of 1–10 kPa. The slow compaction was later investigated. Finally, the compaction dynamic was assessed under alternating high and low ΔP and relaxation in between the filtrations. The findings demonstrated the prominence of membrane compaction, as shown by the decreasing trend in clean water permeability at higher ΔPs (i.e., 3240 and 2401 L m−2 h−1 bar−1 at ΔPs of 1 and 10 kPa, respectively). We also found that the intrinsic permeability of the applied polymeric membrane was significantly higher than the apparent one (4351 vs. 2401 L m−2 h−1 bar−1), demonstrating >50% loss due to compaction. The compaction was mainly instantaneous, which occurred when the ΔP was changed, whereas only minor changes in permeability occurred over time when operating at a constant ΔP. The compaction was highly reversible and could be restored (i.e., decompaction) through relaxation by temporarily stopping the filtration. A small fraction of irreversible compaction could be detected by operating alternating filtrations under ΔPs of 1 and 10 kPa. The overall findings are essential to support emerging GDM filtration applications, in which membrane compaction has been ignored and confounded with membrane fouling. The role of compaction is more prominent for high-flux GDM filtration systems treating less-fouling-prone feed (i.e., rainwater, river water) and involving membrane cleaning (i.e., relaxation) in which both reversible and irreversible compaction occurred simultaneously.

Studying and Analyzing Operating Conditions of Hollow Fiber Membrane Preparation Process

Polymeric hollow fiber membrane is produced by a physical process called wet or dry/wet phase inversion; a technique includes many steps and depends on different factors (starting from selecting materials, end with post-treatment of hollow fiber membrane locally manufactured). This review highlights the most significant factors that affect and control the characterization and structure of ultrafiltration hollow fiber membranes used in different applications. Three different types of polymers (polysulfone PSF, polyethersulfone PES or polyvinyl chloride PVC) were considered to study morphology change and structure of hollow fiber membranes in this review. These hollow fiber membranes were manufactured with different process conditions and a reasonable starting point for factors remained constant to study the changing effect of specific factors.

Low-Molecular-Weight Lignin Recovery with Nanofiltration in the Kraft Pulping Process.

Kraft lignin is an underutilized resource from the pulp and paper industry with the potential of being a key raw material for renewable fuels and chemicals. The separation of high-molecular-weight lignin from black liquor by ultrafiltration has been widely investigated, while the permeate containing low-molecular-weight lignin has received little attention. Nanofiltration can concentrate the low-molecular-weight lignin. This work, therefore, evaluates nanofiltration for the separation and concentration of low-molecular-weight lignin from the ultrafiltration permeate. For this study, eight flat polymeric sheet membranes and one polymeric hollow fiber membrane, with molecular weight cut-offs ranging from 100 to 2000 Da, were tested. A parametric study was conducted at 50 °C, 2.5–35 bar, and crossflow velocity of 0.3–0.5 m/s. At a transmembrane pressure of 35 bar, the best performing membranes were NF090801, with 90% lignin retention and 37 L/m2·h, and SelRO MPF-36, with 84% lignin retention and 72 L/m2·h. The other membranes showed either very high lignin retention with a very low flux or a high flux with retention lower than 80%. Concentration studies were performed with the two selected membranes at conditions (A) 50 °C and 35 bar and (B) 70 °C and 15 bar. The NF090801 membrane had the highest flux and lignin retention during the concentration studies. Overall, it was shown that the nanofiltration process is able to produce a concentrated lignin fraction, which can be either used to produce valuable chemicals or used to make lignin oil.

Braid-reinforced PVDF hollow fiber membranes for high-efficiency separation of oily wastewater

Several efforts to produce mechanically robust polymeric hollow fiber membranes have led to the use of polyethylene terephthalate (PET) hollow braided tubes, which offer rigidity to hollow fiber membranes. However, a compensation of flux exists with increased filtration pathway occasioned by braid substrate and thick polymer coating. It is often difficult to control the fabrication parameters to achieve uniformly coated and thin separation layer. In this work, we report a modification of the erstwhile dry-jet wet spinning process for braided hollow fiber by introducing a loop-system to increase resident time in the coagulation bath for effective solvent exchange and leaching of pore former additive. A combination of air gap (5, 15 and 25 cm), polymer concentration (15%, 17% and 19%) and take-up speed (1.2, 2.4 and 3.6 m/min) were varied to produce membranes with optimum filtration performance against crude oil emulsion feed. BRP-HM8 spun with 15 wt% PVDF, 15 cm air gap and take-up speed of 2 rpm exhibited thin and uniform coating outside of braid, well-developed pore structure resulting in high flux up to 620 L/m2h, good hydrophilic/oleophobic characteristics with > 98% rejection of crude oil as well high mechanical properties against harsh feed and elevated pressure.

Graphene nanoplatelets based polyimide/Pebax dual-layer mixed matrix hollow fiber membranes for CO2/CH4 and He/N2 separations

Mixed matrix membranes are key in the preparation of stable, stretchy, durable and efficient membranes for gas separation applications. To this aim, the perfect filler nanomaterials’ dispersion is needed. At the same time the replacement of toxic solvents with green ones is also a priority in science, including the membrane technology. Herein, we present the development steps, their structural characteristics and the gas selectivity properties of graphene nanoplatelets (GNPs) based mixed matrix hollow fiber (HF) membranes. In specific, dual-layer composite polymeric hollow fiber membranes, for CO2/CH4 and He/N2 gas separations, were prepared by directly dip-coating a single selective layer on prepared porous HF supports without the use of any gutter layer. Asymmetric BTDA-TDI/MDI (P84) co-polyimide-based HFs that acted as porous supports, were fabricated via the dry-wet phase inversion process and the commercial poly(ether-block-amide) Pebax-1657 was chosen as a high CO2-selective separation layer material, dip-coated on the HF supports. The positive influence of the incorporation of GNPs as promising nanofiller in both, the polymeric matrix (support) and the selective layer, in parallel with the partial replacement of toxic NMP by GBL -a "green" solvent- in the support's spinning process, were all evaluated and confirmed. CO2/CH4 and He/N2 selectivities up to 82 and 20, respectively with CO2 and He permeances of 3 and 2.7 GPU, respectively were measured under real binary gas mixture conditions at 1.3 bar(a) transmembrane pressure at 298 K for dual-layer composite, with GNPs filler, HF (DL-HF) membranes.

Optimizing SO2 Adsorption from Flue Gas Using Microporous Polypropylene Hollow Fiber Membrane Contactor

This study optimized the operational parameters of removing SO2 from flue gas via a polymeric hollow fiber membrane contactor (HFMC) using the response surface methodology (RSM). The distilled water and polypropylene hollow fibers were applied as the adsorbent and membrane material, respectively. Three experimental parameters were chosen as independent variables: liquid flow rate, gas flow rate, and initial SO2 concentration. The SO2 removal efficiency was significantly affected by the initial SO2 concentration. The optimal ratio of liquid-to-gas flow rate was found to be 0.25 to reach maximum separation efficiency (98.81%). The optimal value of the liquid flow rate was 33 l/h, and the optimal gas flow rate was 131 l/h. The effect of CO2 presence, module length, fibers number, temperature, and the adsorbent nature were also investigated under optimal values obtained for the ratio of liquid-to-gas flow rate. Results indicated that CO2 presence in the flue gas slightly affects SO2 removal using water as an absorbent in HFCM. Furthermore, it was indicated that the SO2 removal efficiency was a function of the flue gas temperature and number of fibers: it decreased as the temperature rose from 20 to 50°C and the fiber numbers increased from 300 to 1000. This study offers a model to predict the efficiency of SO2 removal using HFMC under different conditions and provides the ground to further explore the industrial applications of this technology.

Fabrication of High Performance PVDF Hollow Fiber Membrane Using Less Toxic Solvent at Different Additive Loading and Air Gap

Existing toxic solvents in the manufacturing of polymeric membranes have been raising concerns due to the risks of exposure to health and the environment. Furthermore, the lower tensile strength of the membrane renders these membranes unable to endure greater pressure during water treatment. To sustain a healthier ecosystem, fabrication of polyvinylidene fluoride (PVDF) hollow fiber membrane using a less toxic solvent, triethyl phosphate (TEP), with a lower molecular weight polyethylene glycol (PEG 400) (0–3 wt.%) additive were experimentally demonstrated via a phase inversion-based spinning technique at various air gap (10, 20 and 30 cm). Membrane with 2 wt.% of PEG 400 exhibited the desired ultrafiltration asymmetric morphology, while 3 wt.% PEG 400 resulting microfiltration. The surface roughness, porosity, and water flux performance increased as the loading of PEG 400 increased. The mechanical properties and contact angle of the fabricated membrane were influenced by the air gap where 20 cm indicate 2.91 MPa and 84.72°, respectively, leading to a stronger tensile and hydrophilicity surface. Lower toxicity TEP as a solvent helped in increasing the tensile properties of the membrane as well as producing an eco-friendly membrane towards creating a sustainable environment. The comprehensive investigation in this study may present a novel composition for the robust structure of polymeric hollow fiber membrane that is suitable in membrane technology.