CS Membrane Research Articles

Improved Proton Conductivity of Chitosan-Based Composite Proton Exchange Membrane Reinforced by Modified GO Inorganic Nanofillers.

Non-fluorinated chitosan-based proton exchange membranes (PEMs) have been attracting considerable interest due to their environmental friendliness and relatively low cost. However, low proton conductivity and poor physicochemical properties have limited their application in fuel cells. In this work, a reinforced nanofiller (sulfonated CS/GO, S-CS/GO) is accomplished, for the first time, via a facile amidation and sulfonation reaction. Novel chitosan-based composite PEMs are successfully constructed by the incorporation of the nanofiller into the chitosan matrix. Additionally, the effects of the type and amount of the nanofillers on physicochemical and electrochemical properties are further investigated. It is demonstrated that the chitosan-based composite PEMs incorporating an appropriate amount of the nanofillers (9 wt.%) exhibit good membrane-forming ability, physicochemical properties, improved proton conductivity, and low methanol permeability even under a high temperature and low humidity environment. When the incorporated amounts of S-CS/GO are 9 wt.%, the proton conductivity of the composite PEMs was up to 0.032 S/cm but methanol permeability was decreased to 1.42 × 10-7 cm2/s. Compared to a pristine CS membrane, the tensile strength of the composite membrane is improved by 98% and the methanol permeability is reduced by 51%.

Fabrication of Antibacterial and Antioxidant ZnO-Impregnated Amine-Functionalized Chitosan Bio-Nanocomposite Membrane for Advanced Biomedical Applications.

Developing a variety of safe and effective functioning wound dressings is a never-ending objective. Due to their exceptional antibacterial activity, biocompatibility, biodegradability, and healing-promoting properties, functionalized chitosan nanocomposites have attracted considerable attention in wound dressing applications. Herein, a novel bio-nanocomposite membrane with a variety of bio-characteristics was created through the incorporation of zinc oxide nanoparticles (ZnONPs) into amine-functionalized chitosan membrane (Am-CS). The developed ZnO@Am-CS bio-nanocomposite membrane was characterized by various analysis tools. Compared to pristine Am-CS, the developed ZnO@Am-CS membrane revealed higher water uptake and adequate mechanical properties. Moreover, increasing the ZnONP content from 0.025 to 0.1% had a positive impact on antibacterial activity against Gram-positive and Gram-negative bacteria. A maximum inhibition of 89.4% was recorded against Escherichia coli, with a maximum inhibition zone of 38 ± 0.17 mm, and was achieved by the ZnO (0.1%)@Am-CS membrane compared to 72.5% and 28 ± 0.23 mm achieved by the native Am-CS membrane. Furthermore, the bio-nanocomposite membrane demonstrated acceptable antioxidant activity, with a maximum radical scavenging value of 46%. In addition, the bio-nanocomposite membrane showed better biocompatibility and reliable biodegradability, while the cytotoxicity assessment emphasized its safety towards normal cells, with the cell viability reaching 95.7%, suggesting its potential use for advanced wound dressing applications.

Preparation of Chitosan/β-Cyclodextrin Composite Membrane and Its Adsorption Mechanism for Proteins.

A significant portion of the protein in food waste will contaminate the water. The chitosan/modified β-cyclodextrin (CS/β-CDP) composite membranes were prepared for the adsorption of bovine serum albumin (BSA) in this work to solve the problem of poor adsorption protein performance and easy disintegration by a pure chitosan membrane. A thorough investigation was conducted into the effects of the preparation conditions (the mass ratio of CS and β-CDP, preparation temperature, and glutaraldehyde addition) and adsorption conditions (temperature and pH) on the created CS/β-CDP composite membrane. The physical and chemical properties of pure CS membrane and CS/β-CDP composite membrane were investigated. The results showed that CS/β-CDP composite membrane has better tensile strength, elongation at break, Young's modulus, contact angle properties, and lower swelling degree. The physicochemical and morphological attributes of composite membranes before and after the adsorption of BSA were characterized by SEM, FT-IR, and XRD. The results showed that the CS/β-CDP composite membrane adsorbed BSA by both physical and chemical mechanisms, and the adsorption isotherm, kinetics, and thermodynamic experiments further confirmed its adsorption mechanism. As a result, the CS/β-CDP composite membrane of absorbing BSA was successfully fabricated, demonstrating the potential application prospect in environmental protection.

Highly efficient chitosan-based bio-polymeric membranes embedded with green solvent encapsulated MIL-53(Fe) for methanol/MTBE separation by pervaporation

An emerging family of solvents known as deep eutectic solvents has been heralded as a sustainable alternative to traditional solvents. Due to the low compatibility with polymeric materials, the direct use of a deep eutectic solvent (DES) as a solvent is still in the challenging phase. Therefore, we have developed a novel strategy to add DES into the polymer matrix. We have encapsulated MIL-53(Fe) using the choline chloride and ethylene glycol DES mixture and incorporated it into the chitosan polymer matrix. This study prepares chitosan-based biodegradable and sustainable membranes by adding different nanofillers such as DES, MIL-53(Fe), and DES@MIL-53(Fe) for methanol/MTBE azeotropic mixture separation. The prepared nanofillers and bio-degradable membranes are characterized using various analytical techniques such as FESEM, HRTEM, AFM, FTIR, XRD, TGA, XPS, mechanical strength, and wettability. The best separation results are found for the DES@MIL-53(Fe)/CS membranes because the membrane exhibit the characteristic of both components together. The highest total flux and methanol selectivity are observed for the F4 membrane, which is 2329 g m−2 h−1 and 207.06. Based on the surface characteristics and performance study, the DES@MIL-53(Fe)/CS membrane can have better potential in wastewater treatment and other membrane-based separation processes.

Fabrication technique of composite chitosan/alginate membrane module for greywater treatment

A novel chitosan/alginate composite membrane is proposed for the application of greywater treatment. In particular, the effect of stirring speed of mixing chitosan and alginate solution was investigated in this study. The study revealed that 150CSAL and 210CSAL membranes swell significantly compared to CS membrane due to the porous structure of composite membrane. The FTIR spectra revealed that the mixing speed has no influence in terms of molecular interaction between CS and AL due to fixed CS and AL concentrations used in this study. On the other hand, the complexation of AL with CS made outstanding improvement to the dense structure of CS where 180CSAL membrane has UP water flux as high as 90 L/m2h at 2 bar. All membranes have the capability to remove the pollutants present in GW and the COD removal was further improved up to 7% using CSAL membranes. In addition, increasing mixing speed improved the pathogen removal efficiency compared to CS membrane. The treated GW met the non-potable GW reuse standard for turbidity<5 NTU and TSS<20 mg/L. To summarize, the proposed fabrication technique on CSAL membrane showed improved characteristics to CS membrane and has significant performance on GW treatment.

High strength antibacterial membranes consisted of nanofibrous chitosan immobilized silver nanoparticles

AbstractChitosan (CS) has biocompatibility and biodegradability, but the bulk CS hydrogel/membranes with its poor strength and limited antibacterial property could not satisfy the practical application. Here green dissolving/regeneration and in situ reduction strategy was combined to construct high strength antibacterial CS membranes. First nanofibrous CS hydrogels were constructed through dissolving CS in LiOH/KOH/urea aqueous system via freezing–thawing process followed regeneration. Then, Ag NPs were immobilized along CS nanofibers through in situ reductions of Ag + by the NH2 group of CS. The obtained NCM‐Ag composite dry membranes are easy for storing and can quick switch to nanofibrous hydrogels as absorbing water. Size of Ag NPs can be controlled to very small until 2 nm by concentration and limited space network. Fourier transform infrared spectroscopy and X‐ray photoelectron spectrometer indicated the forceful grasp ability of CS nanofibers to Ag NPs for a stable binding, mechanical property was enhanced over 100Mpa as the nanofibrous structure and chain linked by Ag coordination. The NCM‐Ag membranes had excellent antibacterial activities against both Staphylococcus aureus and Escherichia coli. Moreover, such nanofibrous CS membrane exhibited good adhesive ability to tissues. Combining all these properties, NCM‐Ag membranes would be potential as antibacterial adhesion barrier to accelerate wound healing.

Synthesis of Chitosan/Maleate-Alumoxane nanocomposite membranes for adsorption of anionic dye

Chitosan/Mal-A nanocomposite membranes were synthesized and used for adsorption of Reactive Yellow 84 (RY 84) from aqueous solution. The membranes were prepared by solution-casting method with 2 wt% Chitosan (Cs) and various ratios of Mal-A (0.3–0.9 wt%). FTIR and SEM analyses were used to characterize the Cs-based membrane. The results showed that a dense-thin-face layer associated with an open-structure layer was formed in the composite membrane containing 0.5 wt% Mal-A. Membrane performance was investigated as dye removal and permeate flux. The significant effects of the operating variables including pH, initial concentration of dye, and Cs/Mal-A dose, were evaluated on RY removal efficiency using response surface methodology (RSM). The results obtained from the experimental data were presented with the quadratic regression model. The adsorption kinetics and equilibrium isotherm were well described by the pseudo-second order and the Langmuir model, respectively. Adding Mal-A nanoparticles to the Cs matrix (0.5wt%) improved liquid permeability by 21% compared with the Cs membrane, while dye removal efficiency for both membranes remained approximately 100% at acidic pH and under a trans-membrane pressure of 3 bar. The protonation of the amine groups in CS/Mal-A results in a positive charge on the membrane surface which causes a complete removal of the anionic dye. The permeability improvement of ∼57.2% for the composite membrane was achieved at a pressure difference of 5 bar, which corresponded to an efficiency reduction of 10%.

Engineering a High-Selectivity PVDF Hollow-Fiber Membrane for Cesium Removal

Abstract In this study, a copper ferrocyanide/silica/polyvinylidene fluoride (CuFC/SiO2/PVDF) hollow-fiber composite membrane was successfully synthesized through a facile and effective crosslinking strategy. The PVDF hollow-fiber membrane with embedded SiO2 was used to fix the dispersion of CuFC nanoparticles for cesium (Cs) removal. The surface morphology and chemical composition of the composite membrane were analyzed using scanning electron microscopy and X-ray photoelectron spectroscopy (XPS). The composite membrane showed a high Cs rejection rate and membrane flux at the three layers of CuFC and 0.5% SiO2, and its Cs rejection rate was not affected by variation in the pH (pH = 4–10). The modified membrane could be effectively regenerated many times using ammonium nitrate (NH4NO3). The Cs selectivity performance was verified by an efficient Cs rejection rate (76.25% and 88.67% in 8 h) in a solution of 100 μg·L−1 of Cs with 1 mmol·L−1 of competing cations (K+ and Na+). The CuFC/SiO2/PVDF hollow-fiber composite membrane showed a particularly superior removal performance (greater than 90%) in natural surface water and simulated water with a low Cs concentration. Therefore, the CuFC/SiO2/PVDF hollow-fiber composite membrane can be used directly in engineering applications for the remediation of radioactive Cs-contaminated water.

Synergy between Isomorphous Acid and Basic Metal-Organic Frameworks for Anhydrous Proton Conduction of Low-Cost Hybrid Membranes at High Temperatures.

Metal-organic frameworks (MOFs) embedded in polymer have showed efficiency in improving proton conduction of hybrid membranes under hydrated conditions. However, anhydrous proton conduction of such hybrid membranes over 100 °C remains great challenge. Here, proton conductive hybrid membranes combined acid group (-SO3H)- and basic group (-NH2)-modified isomorphous MOFs, namely UiO-66(SO3H) (abbreviated as A, the initial of acid) and UiO-66(NH2) (abbreviated as B, the initial of basic) and a low-cost polymer (chitosan, CS) were prepared. The proton conductivity of the optimum dual MOF-cofilled hybrid membranes (CS/A + B) reached 3.78 × 10-3 S/cm at 120 °C and under anhydrous conditions, under which each component, that is MOF A, MOF B and CS, and single MOF-filled hybrid membranes (CS/A and CS/B) nearly lost proton conduction without exception, producing unprecedented results of one plus one more greater than two. The synergistic effects among UiO-66(SO3H), UiO-66(NH2), and CS on improving conductivity are also observed under hydrated conditions, the highest proton conductivity of CS/A + B reached 5.2 × 10-2 S/cm, which is 1.86, compared to that of the pure CS membrane at 100 °C and 98% relative humidity. The anhydrous proton conductivity of CS/A + B over 100 °C is one of the highest for MOF-based hybrid membranes. MOFs and hybrid membranes were extensively characterized and the proton conductive mechanism was revealed. The achievements open a new avenue for MOF-based anhydrous proton-conducting membranes and would advance the exploration of future application of these MOFs in fuel cells.

Reinforced chitosan membranes by microspheres for guided bone regeneration.

In order to improve the osteogenic activity and mechanical strength of the guided bone regeneration (GBR) membrane for repairing bone defect, nano-hydroxyapatite/chitosan (nHA/CS) composite microspheres were prepared through in situ biomimetic method, then composite microspheres were incorporated into CS membrane. The morphologies and mechanical properties of the composite membranes were investigated through scanning electronic microscopy (SEM) and universal mechanical testing machine. The results show that the in situ biomimetic nHA/CS microspheres were embedded in CS membrane and were integrated tightly with CS matrix. The mechanical properties of GBR membranes containing in situ nHA/CS microspheres is significantly higher than that of membranes containing pure CS microspheres and blending nHA/CS microspheres. Its elongation rate at break reaches 5.61 ± 0.95%. The elastic modulus and strength of the GBR membranes can reach 766.27 ± 20.68 and 43.32 ± 0.95 MPa, respectively. Further, The work-of-fracture of the membranes with in situ microspheres approaches 2.71 ± 0.25 J/m2, which is about 3 times of the pure CS membrane. The cell culture results display that the GBR membranes containing in situ biomimetic nHA/CS microspheres exhibit good cytocompatibility.

Fabrication of nano-hydroxyapatite/chitosan membrane with asymmetric structure and its applications in guided bone regeneration.

The development of guided bone regeneration (GBR) technique brings a promising alternative for bone defects and fracture healing. In this study, an asymmetric nano-hydroxyapatite/chitosan (n-HA/CS) composite GBR membrane was fabricated by means of solution-blending and solvent-evaporating in vacuum. The membranes were characterized using SEM, XPS and contact angle. It was found that the composite membrane displayed an asymmetric structure, in which the upper surface was CS and the under surface was a complex of n-HA and CS, and some interactions between n-HA and CS were also confirmed to exist. The contact angle testing showed that the under surface was more hydrophilic than the upper surface. The in vivo experiments demonstrated that the asymmetric composite membrane had the ability to make osteoblasts mineralize and promote loose bone calcified, and then accelerate the bone regeneration. Compared with CS membrane, the asymmetric composite membrane displays a better bone regeneration ability and is suitable for GBR membrane.

CO2 separation performance by chitosan/tetraethylenepentamine/poly(ether sulfone) composite membrane

ABSTRACTCO2 separation from CO2/N2 (20:80) gas mixture has been demonstrated by tetraethylenepentamine blended with chitosan (CS‐TEPA) membrane. Optimization of CS and TEPA weight ratio were carried out based on characterization details involving thermogravimetric analysis, Fourier transform infrared spectroscopy, X‐ray diffraction, atomic force microscope, and field emission scanning electron microscope. Effects of water flow rate, pressure, and temperature were concurrently studied on CS‐TEPA membranes through gas permeation. Almost twofold increase in CO2 permeance (24.7 GPU) was detected in CS blend with 30% (w/w) of TEPA (CS70) as compared to pure CS membrane (12.5 GPU). CS70 yielded CO2/N2 selectivity of 80 whereas CS demonstrated a maximum of 54 at 90 °C. The membrane also exhibited improved stability at temperatures less than 120 °C which was evident from TGA isotherm trace. The proposed composite membrane can be a promising candidate for flue gas separation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45206.

Composite membranes of chitosan and titania‐coated carbon nanotubes as promising materials for new proton‐exchange membranes

ABSTRACTTitania‐coated carbon nanotubes (TCNTs) were obtained by a simple sol–gel method. Then chitosan/TCNT (CS/TCNT) composite membranes were prepared by stirring chitosan/acetic acid and a TCNT/ethanol suspension. The morphology, thermal and oxidative stabilities, water uptake and proton conductivity, and mechanical properties of CS/TCNT composite membranes were investigated. The CNTs coated with an insulated and hydrophilic titania layer eliminated the risk of electronic short‐circuiting. Moreover, the titania layer enhanced the interaction between TCNTs and chitosan to ensure the homogenous dispersion of TCNTs in the chitosan matrix. The water uptake of CS/TCNT composite membranes was reduced owing to the decrease of the effective number of the NH2 functional groups of chitosan. However, the CS/TCNT composite membranes exhibited better performance than a pure CS membrane in thermal and oxidative stability, proton conductivity, and mechanical properties. These results suggest that CS/TCNT composite membranes are promising materials for new proton‐exchange membranes. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43365.

Evaluation of physicochemical and biological properties of chitosan/poly (vinyl alcohol) polymer blend membranes and their correlation for Vero cell growth

The blend membranes with varying weight ratios of chitosan/poly (vinyl alcohol) (CS/PVA) (1:0, 1:1, 1:2.5, 1.5:1, 1.5: 2.5) were prepared using solvent casting method and were evaluated for their potential application in single-use membrane bioreactors (MBRs). The physicochemical properties of the prepared membranes were investigated for chemical interactions (FTIR), surface morphology (SEM), water uptake, protein sorption (qe), ammonia sorption and growth kinetics of Vero cells. CS/PVA blend membrane having weight ratio of 1.5:1 had shown enhanced membrane flexibility, reduced water uptake, less protein sorption and no ammonium sorption compared to CS membrane. This blend membrane also showed comparatively enhanced higher specific growth rate (0.82/day) of Vero cells. Improved physicochemical properties and growth kinetics obtrude CS/PVA (1.5:1) as a potential surface for adhesion and proliferation with possible application in single use membrane bioreactors. Additionally, new insight explaining correlation between water holding (%) of CS/PVA (1.5:1) blend membrane and doubling time (td) of Vero cells is proposed.

Chitosan/silica coated carbon nanotubes composite proton exchange membranes for fuel cell applications

Silica-coated carbon nanotubes (SCNTs), which were obtained by a simple sol–gel method, were utilized in preparation of chitosan/SCNTs (CS/SCNTs) composite membranes. The thermal and oxidative stability, morphology, mechanical properties, water uptake and proton conductivity of CS/SCNTs composite membranes were investigated. The insulated and hydrophilic silica layer coated on CNTs eliminates the risk of electronic short-circuiting and enhances the interaction between SCNTs and chitosan to ensure the homogenous dispersion of SCNTs, although the water uptake of CS/SCNTs membranes is reduced owing to the decrease of the effective number of the amino functional groups of chitosan. The CS/SCNTs composite membranes are superior to the pure CS membrane in thermal and oxidative stability, mechanical properties and proton conductivity. The results of this study suggest that CS/SCNTs composite membranes exhibit promising potential for practical application in proton exchange membranes.

Evaluating the potential of chitosan/poly(vinyl alcohol) membranes as alternative carrier material for proliferation of Vero cells

AbstractChitosan/poly(vinyl alcohol) (CS/PVA) blend membranes were prepared using the casting method and their physiochemical properties were analyzed using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). FTIR and XRD demonstrated possible hydrogen bonds between CS and PVA. The addition of PVA to CS resulted in surface roughness as analyzed by SEM. The CS/PVA blend membrane exhibited high tensile properties (81.62%) and reduced water-holding capacity (53.8%) compared to a pure CS membrane (control). Cell viability and proliferation were assessed via an MTT assay with Vero cell culture. Associated with improved physicochemical properties, the CS/PVA blend membrane promotes cell proliferation of Vero cells with high specific growth rate (0.582 day-1). The results demonstrate that the blending of CS and PVA could significantly alter the surface rugosity, water-holding capacity and improve the mechanical and biological properties of the membrane. Interestingly, this concept can be extended for different anchorage-dependent cell lines, as an alternative carrier material.

Enhanced proton conduction of chitosan membrane enabled by halloysite nanotubes bearing sulfonate polyelectrolyte brushes

Currently, enhancing the proton conductivity is one challenge for chitosan (CS, an industrial waste around the world) membrane to work as proton exchange membrane for direct methanol fuel cell. In this study, halloysite nanotubes bearing sulfonate polyelectrolyte brushes (SHNTs) are synthesized via distillation–precipitation polymerization and then incorporated into CS matrix to fabricate nanohybrid membranes. The membranes are characterized using field emission scanning electron microscope, fourier transform infrared, thermogravimetric analysis, differential scanning calorimetry, and mechanical tester. It is found that SHNTs generate strong electrostatic attractions to CS chains, which inhibit the chain mobility and thus enhance the thermal and mechanical stabilities of nanohybrid membranes. The results of water uptake, area swelling, proton conductivity, and activation energy reveal that the high aspect nanotube and long polyelectrolyte brush allow SHNTs to construct continuous and wide pathways, along which sulfonic acid–amide acid–base pairs are formed and work as low-barrier proton-hoping sites, imparting an enhanced proton transfer via Grotthuss mechanism. In such a way, the proton conductivity of CS membrane is obviously enhanced, and 15% SHNTs can afford a 60% enhancement in conductivity to the nanohybrid membrane, particularly. Moreover, the methanol permeability and selectivity of the as-prepared membranes are investigated in detail.

In vitro and in vivo evaluation of chitosan/β‐glycerol phosphate composite membrane for guided bone regeneration

Chitosan and β-glycerol phosphate (CS/β-GP) composite, with a thermosensitive sol-gel transition behavior, has been tested as one of the viable materials for barrier membrane fabrication. These studies have provided us with a new concept for a guided bone regeneration (GBR) membrane design. The composition, porous structure of the membrane, and the neutral mild preparation procedures make the CS/β-GP membrane a potentially active guide for bone regeneration. In this study, the CS/β-GP composite membrane, with different concentrations of β-GP, was studied to assess their potential utility in GBR application. The initial attachment of the ST2 stromal cell line to the CS/β-GP composite membrane was better than their attachment to the pure CS membrane. The proliferation and osteoblastic differentiation of the cells were much higher on the CS/β-GP composite membrane as compared to the pure CS membrane (p < 0.05). A mild inflammatory response was observed around the implanted CS/β-GP composite membrane without any foreign body reaction that continued up to 4 weeks of postsurgery. This primary study indicated that the in vitro and in vivo bioactivities of the CS/β-GP composite membrane fulfilled the requirements for GBR technique.

Chitosan/polyvinylpyrrolidone‐silica hybrid membranes for pervaporation separation of methanol/ethylene glycol azeotrope

AbstractChitosan (CS)/polyvinylpyrrolidone (PVP)‐silica hybrid membranes are prepared to separate the methanol/ethylene glycol (EG) azeotrope. These hybrid membranes are formed in semi‐interpenetrating network structure at the molecular scale via sol‐gel reactions between CS and tetraethoxysilane (TEOS). The physico‐chemical property and morphology of the as‐prepared membranes are investigated in detail. They have lower crystallinity, higher thermal stability, and denser structure than the pristine CS membrane and its blending counterpart. The as‐prepared hybrid membranes demonstrate excellent performances and a great potential in pervaporation separation of methanol/EG. Silica‐hybridization depressed the swelling degree of membranes in the azeotrope, and remarkably enhanced methanol sorption selectivity. The membrane containing 7.77 wt % PVP and 14.52 wt % TEOS has a permeation flux of 0.119 kg m−2 h−1 and separation factor of 1899. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Polysulfone–Chitosan blend ultrafiltration membranes: preparation, characterization, permeation and antifouling properties

Biocompatible and naturally occurring chitosan was used as an additive for the preparation of a polysulfone ultrafiltration membrane. Two different compositions of polysulfone in N-methylpyrrolidone (NMP) and chitosan in 1% acetic acid were blended to prepare PSf–CS ultrafiltration membranes by the diffusion induced phase separation (DIPS) method. The proper blending of polysulfone and chitosan in PSf–CS membranes was confirmed by ATR-IR analysis. The surface and cross-sectional morphology of the membranes was studied by scanning electron microscopy (SEM). The membrane hydrophilicity was determined by water uptake and contact angle measurements. The PSf–CS membrane showed an enhanced hydrophilicity compared to a PSf ultrafiltration membrane. The time dependent permeation studies revealed the improved flux of PSf–CS membranes. PSf–CS membranes were subjected to bovine serum albumin (BSA) protein rejection studies. An improved antifouling property was observed for PSf–CS blend membranes as compared to pristine PSf ultrafiltration membranes. Both the permeation and antifouling properties of PSf–CS membranes increased with an increase in chitosan composition.