Polyethersulfone Ultrafiltration Membranes Research Articles

Polyethersulfone/Graphene Oxide Ultrafiltration Membranes from Solutions in Ionic Liquid

ABSTRACTNovel high flux polyethersulfone (PES) ultrafiltration membranes were fabricated by incorporating different amounts of graphene oxide (GO) sheets to PES as nanofillers. The membranes were prepared from solutions in 50/50 1-ethyl-3-methylimidazolium-diethylphosphate/N,N-dimethyl formamide. It was observed that the water permeance increased from 550 to 800 L m-2h-1bar-1, with incorporation of 1 wt% GO, keeping a molecular weight cut-off (MWCO) of approximately 32-34 kg mol-1. Cross-sectional scanning electron microscopy images of GO/PES membranes showed the formation of ultrathin selective layer unlike pristine membranes. Contact angle measurements confirmed the increase of hydrophilicity, by increasing the GO concentration. The rejection of humic acid and bovine serum albumin was demonstrated. The mechanical properties were improved, compared with the pristine membranes. The performance was just above the trade-off relationship between permeance and separation factor for PES membranes reported in the literature.

Fabrication of antibacterial mixed matrix nanocomposite membranes using hybrid nanostructure of silver coated multi-walled carbon nanotubes

The function of separation membranes can be significantly improved by the integration of nanoparticles that can improve not only the mechanical properties of the membrane but also reduce the propensity of the surface to foul. The research of the paper presents the development of a novel nanocomposite membrane incorporating antimicrobial nanoparticles which have the potential to lower membrane biofouling; a major problem in many industries that exploit membrane technology. Antibacterial hybrid nanostructures (HNS) comprising of multi-walled carbon nanotubes (MWCNTs) coated with silver nanoparticles (AgNPs) were successfully synthesized via a facile and rapid method using a microwave treatment. The HNS were incorporated into polyethersulfone (PES) ultrafiltration (UF) membranes via the classical phase inversion technique in order to assess their antimicrobial properties against two bacterial species; E. coli and S. aureus. Different techniques were used to characterize HNS powders and a number of loading weights of the HNS were blended with PES flakes to assess the resultant nanocomposite membranes. The nanocomposite membranes displayed an increase in their antibacterial activity against the two species with increasing the loading weight of HNS.

Pilot-scale ceramic membrane filtration of skim milk for the production of a protein base ingredient for use in infant milk formula

The protein composition of bovine skim milk was modified using pilot scale membrane filtration to produce a whey protein-dominant ingredient with a casein profile closer to human milk. Bovine skim milk was processed at low (8.9 °C) or high (50 °C) temperature using ceramic microfiltration (MF) membranes (0.1 μm mean pore diameter). The resulting permeate stream was concentrated using polyethersulfone ultrafiltration (UF) membranes (10 kDa cut-off). The protein profile of MF and UF retentate streams were determined using reversed phase-high performance liquid chromatography and polyacrylamide gel electrophoresis. Permeate from the cold MF process (8.9 °C) had a casein:whey protein ratio of ∼35:65 with no αS- or κ-casein present, compared with a casein:whey protein ratio of ∼10:90 at 50 °C. This study has demonstrated the application of cold membrane filtration (8.9 °C) at pilot scale to produce a dairy ingredient with a protein profile closer to that of human milk.

Influence of nanoparticles on filterability of fruit-juice industry wastewater using submerged membrane bioreactor

In this study, polyethersulfone (PES) ultrafiltration membrane surface was modified with nano-sized zinc oxide (nZnO) and silver (nAg) to improve the membrane filterability of the mixed liquor and used to treat fruit-juice industry wastewater in a submerged membrane bioreactor (MBR). The nAg was synthesized using three different methods. In the first method, named as nAg-M1, PES membrane was placed on the membrane module and nAg solution was passed through the membrane for 24 h at 25 ± 1 °C. In the second method, named as nAg-M2, PES membrane was placed in a glass container and it was shaken for 24 h at 150 rpm at 25 ± 1 °C. In the third method, named as nAg-M3, Ag nanoparticles were loaded onto PES membrane in L-ascorbic acid solution (0.1 mol/L) at pH 2 for 24 h at 150 rpm at 25 ± 1 °C. For the preparation of nZnO coated membrane, nZnO nanoparticles solution was passed through the membrane for 24 h at 25 ± 1 °C. Anti-fouling performance of pristine and coated membranes was examined using the submerged MBR. The results showed that nZnO and nAg-M3 membranes showed lower flux decline compared with pristine membrane. Moreover, pristine and coated PES membranes were characterized using a permeation test, contact angle goniometer, and scanning electron microscopy.

Influence of extreme concentrations of hydrophilic pore-former on reinforced polyethersulfone ultrafiltration membranes for reduction of humic acid fouling

To address the issue of membrane fouling by ubiquitous humic substances, a hydrophilic pore-former–blended polyethersulfone UF membrane was successfully synthesized via the phase inversion method. For the first time, extremely high concentrations of polyvinylpyrrolidone (PVP), up to 20 wt%, were tested as the hydrophilic pore-former in order to determine the optimum concentration for humic acid fouling. Intrinsic membrane parameters such as permeability and selectivity were evaluated using a cross-flow UF filtration setup. Interestingly, as little as 1 wt% added PVP can significantly improve membrane permeability. That tiny amount of added PVP increased membrane flux to 1107 L/m2h·bar from zero flux, with over 90% rejection of humic acid. In addition, pure water permeation increased to over 2400 L/m2h·bar without sacrificing humic acid rejection (around 90%) when 10 wt% PVP was added; pure water permeation decreased to around 1000 L/m2h·bar as added PVP was increased to 20 wt%. The order of water flux increased with the amount of added PVP up to 20 wt% during humic acid fouling while maintaining membrane selectivity. However, the membrane with 10 wt% added PVP showed the best fouling resistance in terms of flux recovery ratio (98%), total flux loss, reversible fouling ratio, and irreversible fouling ratio. Therefore, the addition of 10 wt% PVP is recommended considering cleaning efficiency and the moderately high flux during humic acid fouling for field operation in wastewater reclamation and water treatment processes.

Removal of organic and inorganic substances from industry wastewaters using modified aluminosilicate‐based polyethersulfone ultrafiltration membranes

Membrane separation processes are attracting increasing interest for the treatment of industrial wastewaters owing to its high organic and inorganic content removal efficiency and material stability. Herein, we have presented an approach to modify polyethersulfone (PES) membrane using aluminosilicate particles (ASPs) for high permeability and separation performance against tannery and distillery wastewater. PES:ASPs ultrafiltration membrane was developed by phase inversion technique at different weight ratios of 0:100, 10:90, 20:80, 30:70, and 40:60 of PES:ASPs. The functional groups and hydrophilicity were analyzed by X‐ray diffraction (XRD) and contact angle, respectively. The modified membranes displayed improved wastewater permeability and higher flux compared to the neat PES membrane. The moderate removal of biochemical oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids, chlorides, and sulfates from tannery and distillery wastewaters were attained for all ASPs‐based PES membranes. In the case of tannery effluent treatment, high BOD reduction of 92% was observed for 80:20 weight ratio of PES:ASPs membrane and 75% BOD reduction for the pure PES membrane. The sulfides removal was 2.21 mg L−1 for 90:10 weight ratio of PES:ASPs membrane when compared with the initial quantity of 42 mg L−1 distillery wastewater. The PES:ASPs membrane with 80:20 weight ratios presented the best COD and BOD removal performance. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1612–1620, 2017

Enzymatic hydrolysis of oil palm empty fruit bunch using membrane reactor

Enzymatic hydrolysis of oil palm empty fruit bunch (EFB) was performed in a membrane reactor system. The reactor was incorporated with polyethersulfone (PES) ultrafiltration membrane to increase the cellulose conversion and reduce enzyme dosage. Parameters such as enzyme and substrate loading, transmembrane pressure (TMP) and cross-flow velocity (CFV) were investigated on the filtration flux behaviour and retention characteristics during filtration process. The cellulase enzyme was completely retained as the rejection was above 98 % for all cases and complete transmission of sugar molecules was achieved when polyethersulfone membranes with molecular weight cut-off (MWCO) of 10 kDa was used. Results on hydrodynamic parameters show that the permeate flux increased with increasing TMP and CFV. However, the enzyme and reducing sugar rejection remain fairly constant. The concentration polarisation (up to 75 % of total resistances) was the main factor that contributed to the flux decline followed by cake layer and membrane pores resistances. Cellulase was tested for its reusability up to 216 h in enzymatic membrane reactor. Productivity increased remarkably from 0.003 to 0.01 g reducing sugars/FPU enzyme in batch reactor and enzymatic membrane reactor. These results demonstrate the potential of using coupled enzymatic reactor and membrane separations for the production of reducing sugars and enzyme recovery in EFB hydrolysis.

Evaluation of graphene oxide-coated ultrafiltration membranes for humic acid removal at different pH and conductivity conditions

Abstract Graphene oxides (GO) were coated on three different commercially available polyethersulfone (PES) ultrafiltration membranes (nominal molecular weight cutoffs; 5, 10, and 30 kDa) via a simple vacuum filtration process in our laboratory. The physicochemical properties of resultant membranes were analyzed by Fourier-transform infrared spectroscopy, Raman spectroscopy, field-emission scanning electron microscopy, confocal laser scanning microscopy, and water contact angle measurements. The GO-coated membranes appeared to be more hydrophilic, resulting in approximately 20% higher pure water flux than pristine PES membranes. It was also found that GO nanosheets were not easily damaged or detached from the PES membrane support by filtration or water rinsing due to strong hydrogen bonding interactions between the sulfone and carboxylic groups. Moreover, the humic acid rejection of GO-coated membranes (85.3–93.9%) was significantly higher by approximately 3.4 times depending on various pH and conductivity conditions than that of the pristine PES membranes (25.2–34.8%). Along with the increase in pH and conductivity, HA rejection was slightly increased for both pristine PES and GO-coated membranes: nevertheless, GO-coated membranes (5.3%) were less affected by high pH/conductivity conditions for the humic acid rejection than the pristine PES membranes (19.0%). In particular, it was relatively easier to remove foulant from the GO-coated membrane surface by water rinsing than from the pristine membranes, resulting in high membrane recovery and antifouling capabilities at various pH and conductivity conditions.

A new high performance polyamide as an effective additive for modification of antifouling properties and morphology of asymmetric PES blend ultrafiltration membranes

Polyethersulfone (PES) ultrafiltration membrane with enhanced simultaneous permeability and fouling–resistance property was prepared using a new synthesized aromatic polyamide (PA-6) as an additive. A series of asymmetric membranes were prepared by adding different amounts of PA-6 to the casting solution using the phase inversion induced by immersion precipitation method. Attenuated total reflection-Fourier transform infrared spectra (ATR-FTIR) and water contact angle measurement confirmed the PA-6 enrichment at the membrane surface and increased the membrane hydrophilicity and wettability. The SEM images elucidated the effect of PA-6 addition on the PES membrane morphology by increasing the pore density. The results of filtration performance, which carried out by dead-end filtration of bovine serum albumin (BSA) solution showed that the permeability and fouling resistance property was improved by optimizing the PA-6 content. When the PA-6 content was 2 wt%, the permeability reached approximately 10 times over the pure PES membrane. In comparison to the blend membrane of PES and 2 wt% of polyvinyl pyrrolidone (PVP), the blend membrane of 2 wt% of PA-6 showed significant flux recovery ability. The rejection of all the blended membranes was approximately at high point over 95%. In addition, the results were compared with those obtained using PVP as a usual additive. Although the PVP blended membranes exhibited higher permeability, they showed lower antifouling properties. Finally, a membrane with 1 wt% PVP and 1 wt% PA-6 was prepared and showed the best performance regarding improved permeability and antifouling properties.

Effect of electrokinetic property of charged polyether sulfone membrane on bovine serum albumin fouling behavior

Negatively charged carboxymethylated polyethersulfone (CMPES) and positively charged quaternized polyethersulfone (QAPES) ultrafiltration (UF) membranes were prepared by bulk chemical modification and non-solvent induced phase separation method. The effects of PES membrane interfacial electrokinetic property on the bovine serum albumin (BSA) membrane fouling behavior were studied with the aid of the membrane-modified colloidal atomic force microscopy (AFM) probe. Electrokinetic test results indicated that the streaming potential (ΔE) of QAPES membrane was not consistent with its expected IEC value, however, within the pH range of 3–10, the ζ potentials of two charged-modified PES membranes were more stable than the unmodified membrane. When pH value was 3, 4.7 or 9, the interaction behavior between charged PES membrane and BSA showed that there was significant linear correlation between the jump distance r 0 of membrane-BSA adhesion force (F/R) and the ζ potential absolute value. Charged modification significantly reduced the adhesion of PES membrane-BSA, and the adhesion data was good linear correlated with the flux decline rate in BSA filtration process, especially reflected in the CMPES membrane. The above experimental facts proved that the charged membrane interfacial electric double layer structure and its electrokinetic property had strong ties with the protein membrane fouling behavior.

The Evaluation of Milk Nutrient Content Filtrated by Polyethersulfone Ultrafiltration Membrane with Different Polymer Concentration and Time Filtration

The aim of this study was to determine the effect of polyethersulfone (PES) polymer concentration and filtration time toward the membrane performance (flux) and milk nutrient content (water content, fat and protein). Ultrafiltration membrane was made using PES polymer and polyethylene glycol (PEG) as additive. This research used Split Plot in Time design with five repetitions. The main plot was filtration time and the subplot was level of polymer concentration. The data was analyzed using analysis of variance (ANOVA) and continued by Duncan Test in 5% level if there was a significant effect. The result showed that there was no interaction effect (P>0,05) between polymer concentration and time filtration to membrane flux and milk nutrient content. The difference of polymer concentration affect membrane flux and the milk water content (P 0,05) toward fat and protein content. Water content in milk filtrated by M1 and M3 membrane increased significantly, whereas water content in milk filtrated by M2 membrane decreased significantly. Fat content in milk filtrated by M1, M2 and M3 membrane were decreased. Milk protein content filtrated by M1 and M2 membrane tend to increase, while milk protein content filtrated by M3 membrane tend to decrease. It could be concluded that M2 membrane that containing of 15% PES and 5% PEG was the best membrane for milk filtration with 5 hours time of filtration.

Preparation, characterization and comparison of antibacterial property of polyethersulfone composite membrane containing zerovalent iron or magnetite nanoparticles

Antimicrobial polyethersulfone ultrafiltration membranes containing zerovalent iron (Fe0) and magnetite (Fe3O4) nanoparticles were synthesized via phase inversion method using polyethersulfone (PES) as membrane material and nano-iron as nanoparticle materials. Zerovalent iron nanoparticles (nZVI) were prepared by the reduction of iron ions with borohydride applying an inert atmosphere by using N2 gases. The magnetite nanoparticles (nMag) were prepared via co-precipitation method by adding a base to an aqueous mixture of Fe3+ and Fe2+ salts. The synthesized nanoparticles were characterized by scanning electron microscopy, X-ray powder diffraction, and dynamic light scattering analysis. Moreover, the properties of the synthesized membranes were characterized by scanning electron microscopy energy dispersive X-ray spectroscopy and atomic force microscopy. The PES membranes containing the nZVI or nMag were examined for antimicrobial characteristics. Moreover, amount of iron run away from the PES composite membranes during the dead-end filtration were tested. The results showed that the permeation flux of the composite membranes was higher than the pristine PES membrane. The membranes containing nano-iron showed good antibacterial activity against gram-negative bacteria (Escherichia coli). The composite membranes can be successfully used for the domestic wastewater filtration to reduce membrane biofouling.

Cell membrane mimetic coating immobilized by mussel-inspired adhesion on commercial ultrafiltration membrane to enhance antifouling performance

A facile method of modifying commercial polyethersulfone ultrafiltration membrane (PESUM) was developed based on mussel adhesive mimetic polydopamine (PDA) and cell membrane antifouling phosphorylcholine (PC). The PESUM was firstly coated with a thin PDA layer to confer the membrane adhesive property. A cell membrane mimetic and mussel adhesive mimetic random copolymer (PMEND) bearing both antifouling PC zwitterions and adhesive dopamine groups at different side chains was then immobilized onto the PDA surface by dopamine adhesion from the aqueous solution. The immobilized PMEND spontaneously formed a cell outer membrane mimetic film on the PESUM/PDA surface, which was stable in air, gasoline and pH 3–10 water for more than 2-weeks. Importantly, the water flux of this PESUM/PDA/PMEND membrane could be recovered up to 100% and 93% after one and three cycles of fouling by 1.0mg/mL BSA solution ultrafiltration, respectively. More importantly, the modified membrane could remove more than 99.99% of oil from an 80,000ppm gasoline/water emulsion. Furthermore, this PDA mediated cell outer membrane mimetic modification strategy is substrate independent and can be applied to other membranes and surfaces to enhance antifouling performance.

Effective natural organic matter removal in pond water by carbon nanotube membrane with flocculation/adsorption

A carbon nanotube (CNT) ultrafiltration (UF) membrane was applied to natural organic matter (NOM) removal in pond water treatment. The source water was pretreated by flocculation and/or adsorption prior to the UF process to alleviate permeate flux decline and improve NOM removal efficiency. The performance of a commercial polyethersulfone (PES) UF membrane was compared to evaluate that of the CNT membrane. The CNT membrane outperformed the PES-UF membrane. The permeate flux, total organic carbon and humic acid (HA) removal rate of the CNT membrane was observed to be 230 LMH/bar, 60%, and 80% when 30 mg/L poly aluminium chloride (PACI) flocculation was applied. This highlights that the permeate flux was three times higher with slightly higher rejection efficiency than the PES-UF membrane. In particular, severe permeate flux decline was completely overcome by the CNT membrane with 30 mg/L PACI coagulation. For powder activated carbon (PAC) adsorption, even though there was a severe permeate flux decline in the CNT membrane, almost complete HA removal (98%) was achieved when 0.5 g/L PAC adsorption was coupled. Based on the superior performance of the CNT membrane with pretreatment, the CNT membrane is suggested to be a robust system for a high concentration of organic matter pond water treatment without membrane flux decline.

Understanding of phenolic compound retention mechanisms on PES-UF membrane

Ultrafiltration (UF) is investigated as a possible alternative to remove organic compounds from aqueous synthetic solution. This paper presents a comprehensive study towards a better understanding of phenolic compound retention mechanisms during UF processes. Thus, removal of phenol and resorcinol was studied using a polyethersulfone ultrafiltration (PES-UF) membrane. The influence of main operating conditions (feed concentration, transmembrane pressure, and pH) on the retention was evaluated. Membrane--solute interactions were found to play an important role during the process, suggesting the adsorption of the target compounds on the PES-UF membrane. The level of adsorption was consequently evaluated by measuring the quantity of each compound per surface unit of membrane. According to the kinetic study, the pseudo-first order model was found to fit better the experimental values. The adsorption equilibrium data fit the Langmuir model. In addition, the adsorption mechanism was evaluated by the intraparticle diffusion model and appeared to be a complex mechanism.

Clarification of crude extract of yerba mate (Ilex paraguariensis) by membrane processes: Analysis of fouling and loss of bioactive compounds

The clarification of a crude yerba mate extract using membrane processes was evaluated as a treatment to reduce the turbidity of the aqueous extract prior to its use in food products. The variations in the permeate flux and the concentrations of some phenolic and methylxanthine compounds were investigated during crossflow filtration with α-alumina (MF-alumina) and polyetherimide (MF-PEI) microfiltration membranes and a polyethersulfone ultrafiltration membrane (UF-PES). All membrane systems reduced the initial turbidity (207±25 NTU) to zero. The loss of bioactive compounds was lowest for the MF-PEI membrane (11.0–15.5%). The highest permeate flux (36.33±0.71) was observed for the MF-PEI at 0.02MPa. Also, in the case of the MF-PEI, the permeate flux of the clarified yerba mate extract showed an initial sharp decrease followed by a gradual decline and subsequent stabilization, resulting in the final permeate flux being approximately 65.0% lower than the initial permeate flux. Almost 66% of the total resistance to permeation was attributed to the polarized layer. The predominant fouling mechanism is due the cake layer, indicative of superficial fouling.

Effect of ionic strength on membrane fouling during ultrafiltration of plasmid DNA

Abstract Recent studies have demonstrated that the selectivity of membrane systems for DNA purification can be enhanced by proper selection of solution ionic strength, but these data were all obtained in dilute solutions where fouling is negligible. The objective of this work was to evaluate the effect of solution conditions on the fouling characteristics of both supercoiled and linear plasmid DNA isoforms with different length. Data were obtained using Biomax polyethersulfone ultrafiltration membranes with 300 and 1000 kDa nominal molecular weight cutoffs. Sieving coefficient and filtrate flux data were analyzed using a model based on the partial blockage of the membrane pores by trapped plasmids. Fouling increased dramatically at low ionic strength, with the flux decline parameter for the 3.0 kbp plasmid in a 1 mM NaCl solution being an order of magnitude greater than that in a 10 mM solution. Fouling was also most pronounced for the larger 16.8 kbp plasmid, consistent with the greater probability of plasmid trapping at the pore entrance. These results provide important insights into the development of membrane systems for plasmid DNA filtration in different solution conditions.

A new thin film composite nanofiltration membrane based on PET nanofiber support and polyamide top layer: preparation and characterization

The main objective of this study was to prepare thin film nanofibrous composite (TFNC) membranes based on self-support nanofibrous mats. To this end, polyethylene terephthalate nanofibrous supports were produced by electrospinning technique and subsequently heat treatment was performed to increase mechanical stability of the mats. Then, interfacial polymerization procedure was applied for preparation of TFNC nanofiltration membranes. For comparison, the thin film composite (TFC) nanofiltration membrane was prepared by the same conditions based on polyethersulfone ultrafiltration membrane prepared through phase inversion method. Chemical structure, morphology and mechanical properties were studied by using ATR-FTIR, SEM and tensile tests, respectively. Also, filtration performance was investigated by water flux, rejection, water contact angle and MWCO determination. Results showed that the TFNC nanofiltration membrane had higher salt rejection and four times higher water flux than the TFC nanofiltraion membrane (Na2SO4 rejection and pure water flux were (93 ± 3)%, (34 ± 2.3) L./m2h and (67 ± 4)%, (8 ± 0.9) L./m2h for TFNC and TFC, respectively). At the end, the filtration performance of PET TFNC-NF membrane was compared with other nanofibrous nanofiltration membranes.

Polyethersulfone membranes modified with D-tyrosine for biofouling mitigation: Synergistic effect of surface hydrophility and anti-microbial properties

Biofouling is a critical issue in membrane separations. Development of novel approaches for biofouling mitigation is of crucial importance for membrane-based technologies. In this research, D-tyrosine was immobilized on a polyethersulfone (PES) ultrafiltration membrane (UF) to mitigate biofouling with the synergistic effects of surface hydrophilicity and anti-microbial properties. Results showed that the grafting of D-tyrosine increased the surface hydrophilicity and imparted a smoother surface to the membrane without altering its transport properties. During bovine serum albumen (BSA) filtration tests, the unified membrane fouling index (UMFI) of D-tyrosine-polydopamine (PDA)/PES membrane was only 0.00162, probably half of the PDA/PES membrane’s UMFI without D-tyrosine. The flux recovery ratio (FRR) of the D-tyrosine-PDA/PES membrane was up to 79%, higher than the virgin PES membrane. Moreover, the D-tyrosine-PDA/PES membrane showed better anti-biofouling performance when inoculated with E. coli culture. The proposed membrane surface modification technique paves the way toward realization of biological control for mitigating biofouling by simultaneously enhancing the anti-adhesive and antimicrobial properties of the membrane.

Protein fouling in carbon nanotubes enhanced ultrafiltration membrane: Fouling mechanism as a function of pH and ionic strength

The protein fouling behavior was investigated in the filtration of the multiwall carbon nanotube (MWCNT) composite membrane and commercial polyethersulfone ultrafiltration (PES-UF) membrane. The effect of solution chemistry such as pH and ionic strength on the protein fouling mechanism was systematically examined using filtration model such as complete pore blocking, intermediate pore blocking and cake layer formation. The results showed that the initial permeate flux pattern and fouling behavior of the MWCNT composite membrane were significantly influenced by pH and ionic strength while the effect of PES-UF membrane on flux was minimal. In a lysozyme (Lys) filtration, the severe pore blocking in the MWCNT membrane was made by the combined effect of intra-foulant interaction (Lys-Lys) and electrostatic repulsion between the membrane surface and the foulant at pH 7, and increasing ionic strength where the foulant-foulant interaction and membrane-fouling interaction were weak. In a bovine serum albumin (BSA) filtration, severe pore blocking was reduced by less deposition via the electrostatic interaction between the membrane and foulant at pH 4.7 and 10.4 and increasing ionic strength, at which the interaction between the membrane and BSA became weak. For binary mixture filtration, the protein fouling mechanism was more dominantly affected by foulant-foulant interaction (Lys-BSA, Lys-Lys, and BSA-BSA) at pH 7.0 and increase in ionic strength. This research demonstrates that MWCNT membrane fouling can be alleviated by changing pH condition and ionic strength based on the foulant-foulant interaction and the electrostatic interaction between the membrane and foulant.