Dual-layer Hollow Fiber Research Articles

Preparation of BCYF0.10–YDC/BCYF0.10–Ni dual-layer hollow fiber membrane for dry reforming of methane and hydrogen purification

A ceramic hydrogen permeable membrane reactor for dry reforming of methane (DRM) enables both the reaction and separation processes to be carried out simultaneously, producing synthesis gas and pure hydrogen while mitigating greenhouse gas emissions.

Grand Challenges in Fabrication of Nanocomposite Hollow Fiber Membranes

Membrane processes allow scalable and energy-efficient separation of gas and liquid, advance low-carbon purifications in various industrial and environmental applications and enable more resilient economy and society. In pursuit of developing more advanced membranes with continuously improved separating performances, nanofillers have been commonly incorporated into membranes to upgrade membrane properties such as mechanical robustness, antifouling ability, and permeability etc., across all types of popular membrane geometries from flat sheet and spiral wound to hollow fiber. Nanofillers inside hollow fibre membranes have received more attentions due to the unique structural advantages such as a large surface area/volume ratio and compact module designs. The resultant nanocomposite hollow fiber membranes thus combine the structural superiority with specific functions of nanomaterials such as superhydrophilicity or catalytic activity, whereas the development of dual layer hollow fiber membrane allowed further design of both the inner and outer membrane layers with innovative functions. On the other hand, greener and more environmentally friendly membranes fabrication are increasingly important to sustainable membrane technology, for example topics of using natural polymers, solvent free membrane fabrication and nano-pollutions are fervently investigated.

PPSU dual layer hollow fiber mixed matrix membranes with functionalized MWCNT for enhanced antifouling, salt and dye rejection in water treatment

AbstractLoose nanofiltration dual layer hollow fiber membranes (DLHFM) were prepared from polyphenylsulfone (PPSU) with a thin contact mixed matrix membrane (MMM) outer layer containing functionalized multiwalled carbon nanotubes (MWCNT). Two types of MWCNT were used; oxidized MWCNT (OMWCNT) and polyethyleneimine (PEI) functionalized MWCNT (PEI‐MWCNT). Z potential measurements indicate that OMWCNT and PEI‐MWCNT were negatively charged, being OMWCNT most negative. Na2SO4, MgSO4, and methylene blue (MB) rejection was enhanced due to OMWCNT and PEI‐MWCNT incorporation in DLHFM outer layer. Enhanced hydrophilicity and negatively charge mixed matrix DLHFM layer was the key factor for a better mixed matrix DLHFM performance. The best salt and MB rejection was found in those membranes prepared with (OMWCNT) followed by (PEI‐MWCNT) compared with neat PPSU membranes. An increase of 113% and 100% in Na2SO4 and MB rejection respectively was attained in DLHFM with 0.04 wt%, OMWCNT (relative to dope's weight) in comparison with the neat PPSU membrane. Antifouling test for bovine serum albumin (BSA) and MB showed better performance also for the mixed matrix DLHFM containing OMWCNT's. In antifouling tests, a 4.4% and 25% flux recovery increase for MB and BSA respectively was obtained in DLHFM with 0.04 wt% OMWCNT compared with the neat PPSU DLHFM.

Visible-light-driven photocatalytic dual-layer hollow fibre membrane ameliorates the changes of bisphenol A exposure in gastrointestinal tract.

Various treatments of choice are available to overcome contamination of bisphenol A (BPA) in the environment including membrane technologies; however, the treatment still releases contaminants that threaten the human being. Therefore, the present study is conducted to investigate the degradation of BPA by recently developed visible-light-driven photocatalytic nitrogen-doping titanium dioxide (N-doped TiO2) dual-layer hollow fibre (DLHF) membrane and its efficiency in reducing the level of BPA in contaminated water. Fabricated with suitable polymer/photocatalyst (15/7.5 wt.%) via co-extrusion spinning method, the DLHF was characterized morphologically, evaluated for BPA degradation by using submerged photocatalytic membrane reactor under visible light irradiations followed by the investigation of intermediates formed. BPA exposure effects were accessed by immunohistochemistry staining of gastrointestinal sample obtained from animal model. BPA has been successfully degraded up to 72.5% with 2 intermediate products, B1 and B2, being identified followed by total degradation of BPA. BPA exposure leads to the high-intensity IHC staining of Claudin family which indicated the disruption of small intestinal barrier (SIB) integrity. Low IHC staining intensity of Claudin family in treated BPA group demonstrated that reducing the level of BPA by N-doped TiO2 DLHF is capable of protecting the important component of SIB. Altogether, the fabricated photocatalytic DLHF membrane is expected to have an outstanding potential in removing BPA and its health effect for household water treatment to fulfil the public focus on the safety of their household water and their need to consume clean water.

Dual-layer hollow fibre haemodialysis membrane for effective uremic toxins removal with minimal blood-bacteria contamination

Bacterial endotoxin contamination in dialysate may pass through haemodialysis membrane and cause a silent chronic microinflammation to kidney patients. Dual-layer hollow fibre (DLHF) membranes with dual function, biocompatible adsorptive and antibacterial effects were developed to solve the problem of incompatible membrane and endotoxin contamination. All membranes were fabricated via the co-extrusion dry-wet phase inversion technique. In this study, silica/α-mangostin nanoparticle was incorporated into the inner layer of membrane to enhance the biocompatibility of the membrane while maintaining its adsorption capacity. Activated carbon (AC) was incorporated in the outer layer of membrane for improved antibacterial property. The DLHF membranes were characterised based on its morphology and surface hydrophilicity. The performance of the DLHF membranes was evaluated in terms of permeability, urea, and creatinine removal capabilities, bovine serum albumin (BSA) rejection and antibacterial properties. The dense and small pore size on the outer layer of AC created a smoother surface for the DLHF membrane. The BSA rejection of the DLHF membranes was enhanced by 6–8% compared to that of unmodified single layer hollow fibre membrane. Silica/α-mangostin nanoparticle in the inner layer of membrane enhanced the removal of urea and creatinine by chemisorption. Result also showed that the incorporation of AC in the outer layer of DLHF membrane successfully filtered bacteria by bacteria entrapment. DLHF membrane with the combination of silica/α-mangostin nanoparticle in the inner layer and AC in the outer layer possessed the higher bacteria inhibition into blood compartment against Escherichia coli and Staphylococcus aureus, with removal rate of 68% and 75%, respectively, and better urea and creatinine removal by 60.57% and 75.18%, respectively, compared to single-layer PSf based membrane. The development of co-adsorptive biocompatible DLHF membrane can play an important role in improvement of kidney patient life.

Bisphenol A Removal Using Visible Light Driven Cu2O/PVDF Photocatalytic Dual Layer Hollow Fiber Membrane.

Bisphenol A (BPA) is amongst the endocrine disrupting compounds (EDCs) that cause illness to humans and in this work was removed using copper (I) oxide (Cu2O) visible light photocatalyst which has a narrow bandgap of 2.2 eV. This was done by embedding Cu2O into polyvinylidene fluoride (PVDF) membranes to generate a Cu2O/PVDF dual layer hollow fiber (DLHF) membrane using a co-extrusion technique. The initial ratio of 0.25 Cu2O/PVDF was used to study variation of the outer dope extrusion flowrate for 3 mL/min, 6 mL/min and 9 mL/min. Subsequently, the best flowrate was used to vary Cu2O/PVDF for 0.25, 0.50 and 0.75 with fixed outer dope extrusion flowrate. Under visible light irradiation, 10 mg/L of BPA was used to assess the membranes performance. The results show that the outer and inner layers of the membrane have finger-like structures, whereas the intermediate section of the membrane has a sponge-like structure. With high porosity up to 63.13%, the membrane is hydrophilic and exhibited high flux up to 13,891 L/m2h. The optimum photocatalytic membrane configuration is 0.50 Cu2O/PVDF DLHF membrane with 6 mL/min outer dope flowrate, which was able to remove 75% of 10 ppm BPA under visible light irradiation without copper leaching into the water sample.

Highly efficient recovery of hydrogen from dilute H2-streams using BaCe0.7Zr0.1Y0.2O3-δ/Ni-BaCe0.7Zr0.1Y0.2O3-δ dual-layer hollow fiber membrane

BaCe0.7Zr0.1Y0.2O3-δ/Ni-BaCe0.7Zr0.1Y0.2O3-δ dual-layer hollow fiber membranes are prepared by a co-spinning/co-sintering method, which is a simple and practical technique to integrate the electrolyte (BaCe0.7Zr0.1Y0.2O3-δ) and the electrode (Ni-BaCe0.7Zr0.1Y0.2O3-δ). A galvanic hydrogen pump is assembled by using this dual-layer hollow fiber membrane for hydrogen separation from dilute H2 streams, in which the hydrogen permeation can be moderately controlled by the applied voltage. At 550℃ and 2 V voltage, a hydrogen flux of 2.15 mL·min−1·cm−2 and a hydrogen recovery rate of 81% are obtained when the feed is low concentration (13 vol%) H2 stream. The one-step manufacturing method of integrating electrolytes and electrodes can be regarded as a more efficient method for the mass production of micro-tubular galvanic hydrogen pumps.

Grand Challenges of Perovskite and Metal Oxide-based Membrane: A Form of Dual-layer Hollow Fibre

Perovskite and metal oxides-based dual-layer hollow fibre membrane (DHF) has a high appeal as separator and catalyst for methane conversion application which operated at intermediate and high temperature. The membrane mostly fabricated via the co-extrusion followed by co-sintering method, which is quite challenging, due to the complexity to handle the barrier between layers from delamination, membrane cracking and crystal structure distortion which affects the material performance in a DHF form. This recent review clarifies the challenges in the DHF fabrication process to regulate physical and chemical properties in terms of mechanical strength, tightness, elemental distribution, and crystal structure stability. The based material of the membrane focuses on NiO-YSZ in the inner layer directly interconnected with LSCF-YSZ in the outer layer. The understanding of the challenges in DHF fabrication, will further reduce crucial errors in the fabrication process and accelerate performance improvement for application such as syngas, methanol and long-chain hydrocarbons production, and solid oxide fuel cell.

A dual-layer ZnO–Al2O3 hollow fiber for directly inducing the formation of ZIF membrane

Despite many methods available to synthesize MOF membrane, the cost-effective synthesis with high reproducibility and scalability is still a challenge. We present here a homologous support-induced approach for the growth of ZIF membrane supported on the dual-layer ZnO–Al2O3 hollow fibers, which has the potential for applications at larger scales. The developed unique dual-layer hollow fibers consisting of a thin outer ZnO layer firmly attached onto an inner porous alumina substrate were realized through one-step co-extrusion/sintering technique. During the MOF membrane synthesis, ZnO can be used not only as the support, but also as the nucleation sites and growth centers for the ZIF-8 membrane formation. More importantly, ZnO can act as a transitional bridge to direct the membrane growth outward along the support and inward embedded into the support, which significantly improving the binding force between the support and MOF, thus bringing in the outstanding membrane stability. Permeation of single gas and separation of binary mixtures revealed that the prepared membranes were free of defects. The resultant ZIF-8 composite membrane exhibits good hydrogen separation performance and excellent reproducibility. This protocol can achieve an easy and large-scale synthesis. In addition to ZIF-8 membrane, ZIF-67 membrane was also successfully synthesized via this method, which may provide some general guidelines for the preparation of other MOF membranes.

Novel ceramic hollow fibre membranes contactor derived from kaolin and zirconia for ammonia removal and recovery from synthetic ammonia

The adverse effects of ammonia found in wastewater streams lead to the development of advanced water treatment technology, i.e. membrane contactor (MC). In this study, single layer hollow fibre membrane (SLZK) and dual layer hollow fibre membrane (DLZK) were prepared from zirconia and kaolin and modified into hydrophobic membrane through simple grafting process via fluoroalkylsilane (FAS) agent. The properties of membranes such as morphology, surface roughness, mechanical strength, wettability and liquid entry pressure were analysed through scanning electron microscopy (SEM), atomic force microscopy (AFM), 3-point bending strength, contact angle and LEPw setup. Finally, the performance of the membranes was also investigated towards ammonia removal via membrane contactor system. Our findings showed that hydrophobicity properties significantly improved for both SLZK and DLZK membranes after grafting modification process as indicated by the increase of contact angle value from 5° and 1° to 132.7° and ~180.0° respectively. Based on the morphological analysis, the surface of DLZK showed more porous structure as compared to the SLZK. In addition, DLZK also displayed the highest mechanical strength and contact angle reading of 125 MPa and ~180° respectively. This suggests that the DLZK showed an excellent membrane contactor performance with highest value of mass transfer coefficient (3.77 x 10-5 ms-1) and almost complete removal of ammonia removal (91%). Overall, these results implied that dual layer ceramic membrane developed from kaolin and zirconia could provide the basis for the development of alternative ceramic membrane with excellent properties for membrane contactor system.

Silver doped titania nanotubes incorporated photocatalytic dual layer antibiofouling hollow fiber membrane for palm oil wastewater treatment

Photocatalytic dual layer hollow fiber membrane (DLHFM) is advantageous over its single layer counterpart due to a better photocatalyst dispersion on the outer layer to maximize the potential of the photocatalyst in improving the overall membrane performance. In this study, a polyvinylidene fluoride (PVDF) dual-layer hollow fiber membrane with antibiofouling properties was successfully synthesized via dry-wet spinning phase inversion method, where the Ag-TNT was incorporated onto the outer layer membrane for photocatalytic degradation of AT-POME pigments in a submerged membrane photoreactor (SMPR). The results revealed that the incorporation of Ag-TNT into the PVDF matrix increased pure water flux from 16.20 L/m2 h for pristine PVDF membrane to 37.12 L/m2 h. The synergistic advantages of photocatalysis and membrane filtration was exhibited by the photocatalytic Ag-TNT membrane which showed the highest AT-POME color removal efficiency of 84.0% compared to the other membranes prepared in this work. With the presence of silver nanoparticles, the modified membrane exhibited antibacterial efficiency of 95.8% with a 1.73 mm inhibition zone around the membrane against P. aeruginosa. Based on the results obtained, the photocatalytic PVDF Ag-TNT membrane showed immense potential as an innovative technology for water reclamation in the palm oil industry.

Dual Layer Hollow Fiber Membranes with Functionalized Separation Layer for Improved Hydrophilicity

AbstractPolyethersulfonbasierte Hohlfasermembranen mit einer hydrophil funktionalisierten Trennschicht wurden hergestellt und untersucht. In die Trennschicht wurde ein amphiphiles Triblockcopolymer mit verschiedenen Konzentrationen integriert. Um eine gesteigerte Hydrophilie und damit assoziiertes verringertes Fouling zu erreichen, bestehen die Blockcopolymere aus zwei äußeren Poly(ethylenoxid)‐Blöcken. Diese flankieren den inneren Polyethersulfonblock, welcher der Verankerung des Additivs in die Membran dient. Gesteigerte Hydrophilie, gepaart mit Permeanzen von 2000 L m−2h−1bar−1 und einem Rückhalt von 100 kDa, kennzeichnete die vielversprechendste Membran dieser Studie.

Comparative DCMD performance of hydrophobic-hydrophilic dual-layer hollow fibre PVDF membranes incorporated with different concentrations of carbon-based nanoparticles

High wetting resistance and high permeate flux are crucial for membrane distillation (MD) to achieve a high performance. To achieve both of these qualities, this work focused on the fabrication of co-extruded dual-layer hollow fibre polyvinylidene fluoride nanocomposite membranes with hydrophobicity gradients. The nanocomposite membranes were incorporated with hydrophobised carbon-based nanoparticles, i.e. multi-walled carbon nanotube (MWCNT) and graphene nanoplatelet (GNP). The effect of different concentrations of nanoparticles (0, 1 and 2 wt%) on the properties and MD performance of the membranes were investigated. The outer layers of the nanocomposites membranes were more hydrophobic than the neat membrane, and the membrane containing 2 wt% of hydrophobised GNP exhibited the highest contact angle of 111.1°. All the inner layers of the membranes were found to be hydrophilic with contact angle of about 60°, thus proving that hydrophobicity gradients were achieved in the membranes. All the membranes had pore sizes and porosities around 0.1 μm and 21.8–42.9% respectively, which are suitable to be used in MD. The surface roughness and wetting resistance of all the nanocomposite membranes, especially the ones with GNP, were higher than the neat membrane and the values increased with increasing concentration of nanoparticles. These membrane characteristics had effects on the direct contact MD (DCMD) performance where all the nanocomposite membranes showed better flux than the neat membrane. The membrane incorporated with 2 wt% of hydrophobised GNP achieved the highest flux of 8.27 kg/(m2h). All the membranes achieved salt rejections of more than 99.9%.

Fabrication of zirconia-kaolin dual layer hollow fiber membrane: Physical and performance study for industrial wastewater treatment

This work aims to prepare a robust yet low-cost dual-layer hollow fibre ceramic membrane composite membrane (DLZK) fabricated by co-extrusion phase inversion/co-sintering technique to be used in wastewater treatment. The dope suspensions were extruded simultaneously where the outer layer consists of zirconia while the inner layer consists of a mixture of kaolin and zirconia to enhance membrane performance in terms of mechanical strength and wastewater treatment capability. The effects of co-sintering temperature from 1200 to 1500 °C on the membrane’s mechanical strength, porosity, pore size, water permeability, and dissolubility in high alkaline/pH condition were investigated. The membrane performance was evaluated by real wastewater treatment test using two different types of industrial wastewaters which are palm oil mill effluent and textile industry wastewater. The findings show that the proposed method of producing the DLZK membranes could provide good interfacial adhesion and well-dispersed zirconia in the outer layer and the use of kaolin as an alternative natural material for ceramic membrane fabrication. The DLZK co-sintered at 1200 °C had the mechanical strength of 65 MPa, only 3.5 % loss of the original shape in high alkaline solution, and removed almost 95 % for all parameters of COD, TOC, TN, NH3-N and TSS in the both wastewaters suitable for microfiltration purpose.

Designing scalable dual-layer composite hollow fiber nanofiltration membranes with fully cross-linked ultrathin functional layer

The treatment of industrial wastewater containing complex foulants demands high efficiency yet cost-effective separation process. The composite hollow fiber nanofiltration membranes suffer from tedious fabrication procedures, impeding the large volume fabrication and application. Herein, we reveal a very simplified designing strategy by polyelectrolyte modification of the co-extruded polyimide/polyethersulphone dual-layer hollow fibers with hierarchical structure and chemistry. The active layer's thickness of the dual-layer hollow fiber substrate is only 800 nm, the thinnest in literature. Compared to integral active single layer hollow fiber, the ultrathin active layer not only leads to over 4 times increase in mechanical flexibility and tenfold reduction in material cost but also enables fully chemical transition from imide to cross-linked polyamide, minimizing the intrinsic hydrolysis tendency of active material. The optimized membranes with a well-defined pore radius of 0.23 nm have 93–95% rejection to Mg2+ and Ca2+ and PWP of 9.1 LMH/bar. Moreover, the composite membranes exhibit backwash ability and stability in the heated feed solutions, which meets the demand for direct treatment of industrial effluents. This work paves the way for the large volume fabrication and application of hollow fiber nanofiltration membranes for treating municipal water, industrial wastewater, and other applications.

Advanced multiple-layer composite CTA/CDA hollow fiber membranes for CO2 separations

CO2 separation has become an important global agenda because of the requirements of industrial products and CO2-induced global warming. Membrane-based technologies have provided an alternative for CO2 separation. To make membrane-based separation more competitive, membranes must have a high permeance and high selectivity. Herein, we have developed a new high-performance multiple-layer hollow fiber membrane of cellulose triacetate (CTA) and cellulose diacetate (CDA) blends for CO2 separation. CTA and CDA blends were chosen because they have similar chemical structures, good separation performance, economical and green nature. Both single-layer and dual-layer hollow fibers were fabricated by various spinning strategies. The optimized dual-layer membrane spun at outer dope flow rate of 1 mL/min exhibits a CO2 permeance of 45 GPU and an ideal CO2/CH4 selectivity of 30.3 at 2 bar. Comparing with the optimized single-layer hollow fiber spun at 5 cm air gap distance and 15 m/min take-up speed, the former has a 100% higher CO2 permeance without compromising the selectivity. The as-produced hollow fibers display a plasticization pressure of about 10 bar. In addition, they have impressive mixed gas CO2/CH4 selectivity of >40 at 2 bar. Therefore, the newly developed dual-layer hollow fiber membranes may have great potential for CO2/CH4 separation.

Delamination of single layer hollow fiber membranes induced by bi-directional phase separation

Structural delamination across the hollow fiber wall is a major challenge for the fabrication of dual-layer hollow fiber membranes. Delamination may also exist in single-layer hollow fiber membranes because the dope solution undergoes phase separation at both inner and outer surfaces. Different phase inversion mechanisms and rates at the inner and outer surfaces result in hollow fibers with different morphologies across the wall and may lead to delamination between the layers. In this work, the origins of delamination for single-layer hollow fiber membranes are investigated. The effects of dope composition, bore fluid chemistry as well as spinning conditions on delamination are disclosed. Among these parameters, bore fluid composition has the most profound impact on fiber delamination. With carefully designed spinning conditions (e.g. high air gap and take-up speed), the occurrence of fiber delamination can be mitigated. A membrane with a delaminated inner layer often possesses a highly porous inner surface with an improved permeance for water filtration. This work offers feasible solutions to resolve structural delamination of hollow fiber membranes during spinning. It may also provide a new method to fabricate high-flux hollow fiber membranes by producing fiber delamination intentionally.

Crosslinked PVDF based hydrophilic-hydrophobic dual-layer hollow fiber membranes for direct contact membrane distillation desalination: from the seawater to oilfield produced water

Crosslinked polyvinylidene fluoride (PVDF) based hydrophilic-hydrophobic dual-layer hollow fiber membranes were fabricated for direct contact membrane distillation (DCMD). PVDF/ammonia/water dope solution was formulated with a spinning process delay of 9 days for the formation of a mechanically robust and hydrophobic crosslinked PVDF outer layer, and polyethylene glycol 6000 (PEG-6000) was introduced to create a thick hydrophilic PVDF/PEG-6000 inner layer. The influences of ammonia/water contents and the spinning process delay on the membrane morphology were studied. The DCMD performances were investigated using both simulated seawater and actual oilfield produced water as the feed solutions. The incorporation of ammonia/water mixture allowed a slow PVDF crystallization in the dope solution during the 9 days of spinning process delay. The obtained membrane DN2H2-9 showed contact angles of 133.6° and 47.1°on the surfaces of the crosslinked PVDF outer layer and PVDF/PEG-6000 inner layer, respectively. The membrane DN2H2-9 showed a superior permeate water flux of 97.6 kg m−2 h−1 and an energy efficiency of 92.8% to desalinate a 3.5% NaCl solution. The result from a 200 h continuous DCMD operation revealed a stable permeate water flux and more than 99.9% of salt rejection, which was attributed to a relatively high liquid entry pressure (LEP) of 1.95 bar and the simultaneously enhanced mechanical strength of the membrane. The membrane DN2H2-9 also demonstrated promising DCMD performance in the desalination of the real oilfield produced water with a high total dissolved solids (TDS), including almost 100% of permeate water recovery and more than 99.9% of salt rejection in 72 h of operation.

Hydrophilic Dual Layer Hollow Fiber Membranes for Ultrafiltration.

In this study, a triblock copolymer was used as additive to fabricate new dual layer hollow fiber membranes with a hydrophilic active inner surface in order to improve their fouling resistance. The polymeric components of the solutions for membrane fabrication were poly(ether sulfone), poly(N-vinyl pyrrolidone), and the triblock copolymer. The additive consists of three blocks: a middle hydrophobic poly(ether sulfone) block and two outer hydrophilic alkyl poly(ethylene glycol) blocks. By varying the additive concentration in the solutions, it was possible to fabricate dual layer hollow fiber membranes that are characterized by a hydrophilic inner layer, a pure water permeance of over 1800 L/(m2 bar h) and a molecular weight cut-off of 100 kDa similar to commercial membranes. Contact angle and composition determination by XPS measurements revealed the hydrophilic character of the membranes, which improved with increasing additive concentration. Rheological, dynamic light scattering, transmission, and cloud point experiments elucidated the molecular interaction, precipitation, and spinning behavior of the solutions. The low-molecular weight additive reduces the solution viscosity and thus the average relaxation time. On the contrary, slow processes appear with increasing additive concentration in the scattering data. Furthermore, phase separation occurred at a lower non-solvent concentration and the precipitation time increased with increasing additive content. These effects revealed a coupling mechanism of the triblock copolymer with poly(N-vinyl pyrrolidone) in solution. The chosen process parameters as well as the additive solutions provide an easy and inexpensive way to create an antifouling protection layer in situ with established recipes of poly(ether sulfone) hollow fiber membranes. Therefore, the membranes are promising candidates for fast integration in the membrane industry.

Co-Adsorptive Removal of Creatinine and Urea by a Three-Component Dual-Layer Hollow Fiber Membrane.

The development of wearable artificial kidney demands an efficient dialysate recovery, which relies upon the adsorption process. This study proposes a solution to solve the problem of competitive adsorption between the uremic toxins by employing two adsorptive components in a membrane separation process. Dual-layer hollow fiber (DLHF) membranes, which are composed of a polysulfone (PSf)/activated carbon (AC) inner layer and a PSf/poly(methyl methacrylate) (PMMA) outer layer, were prepared for co-adsorptive removal of creatinine and urea from aqueous solution. The DLHF membranes were characterized in terms of morphological, physicochemical, water transport, and creatinine adsorption properties. The membrane was then subjected to an ultrafiltration adsorption study for performance evaluation. The incorporation of AC in membrane, as confirmed by microscopic and surface analyses, has improved the pure water flux up to 25.2 L/(m2 h). A membrane with optimum AC loading (9 wt %) demonstrated the highest maximum creatinine adsorption capacity (86.2 mg/g) based on the Langmuir adsorption isotherm model. In the ultrafiltration adsorption experiment, the membrane removed creatinine and urea with a combined average percent removal of 29.3%. Moreover, the membrane exhibited creatinine and urea uptake recoveries of 98.8 and 81.2%, respectively. The combined action of PMMA and AC in the PSf DLHF membrane has made the adsorption of multiple uremic toxins possible during dialysate recovery.