Bovine Serum Albumin Rejection Research Articles

Poly(vinylidene fluoride) ultrafiltration membranes tailored with zirconium‐based MOF‐801 for water treatment applications

AbstractHighly hydrophilic and antifouling poly(vinylidene fluoride) (PVDF) ultrafiltration membranes are developed with excellent permeation using a zirconium‐based metal–organic framework (MOF‐801). MOF‐801 is synthesized by a solvothermal method using zirconium(IV) oxychloride octahydrate (ZrOCl2⋅8H2O) and fumaric acid. The chemical functionality of MOF‐801 is studied by Fourier transform infrared (FTIR) spectroscopy and X‐ray diffraction (XRD) whereas surface morphology and elemental composition are probed by scanning electron microscopy (SEM)/energy‐dispersive X‐ray analysis (EDX). The PVDF/MOF‐801 membranes are characterized in terms of FTIR, XRD, FESEM/EDX and atomic force microscopy. The performance of the hybrid PVDF/MOF‐801 membranes in terms of pure water flux and antifouling ability is found to be improved compared with bare PVDF membranes. The wettability of the membranes is measured by water contact angle and found to be 76.7° for bare PVDF membrane, which decreases upon the addition of MOF‐801 to 55.1° due to the increase in surface hydrophilicity. A notable increase in roughness of 226.29 nm and a porosity of 67.91% is observed for the addition of 2 wt% MOF‐801 in PVDF membrane matrix. The flux recovery ratio of the hybrid membrane is increased from 66.4% to 89.6% and from 68.3% to 85.2% for bovine serum albumin (BSA) and humic acid (HA) separation, respectively. In addition, the reversible and irreversible fouling performance during the rejection of BSA (93%) and HA (88%) indicates the enhanced antifouling property of the PVDF/MOF‐801 membranes. A zone of inhibition test evidences the outstanding antibiofouling activity of the PVDF/MOF‐801 membranes against E. coli and S. aureus. Overall results demonstrated the suitability of hybrid PVDF/MOF‐801 membranes for water and wastewater treatment. © 2023 Society of Industrial Chemistry.

Sustainable additive manufacturing of polysulfone membranes for liquid separations

Membranes serve as important components for modern manufacturing and purification processes but are conventionally associated with excessive solvent usage. Here, for the first time, a procedure for fabricating large area polysulfone membranes is demonstrated via the combination of direct ink writing (DIW) with non-solvent induced phase inversion (NIPS). The superior control and precision of this process allows for complete utilization of the polymer dope solution during membrane fabrication, thus enabling a significant reduction in material usage. Compared to doctor blade fabrication, a 63% reduction in dope solution volume was achieved using the DIW technique for fabricating similarly sized membranes. Cross flow filtration analysis revealed that, independent of the manufacturing method (DIW vs. doctor blade), the membranes exhibited near identical separation properties. The separation properties were assessed in terms of bovine serum albumin (BSA) rejection and permeances (pressure normalized flux) of pure water and BSA solution. This new manufacturing strategy allows for the reduction of material and solvent usage while providing a large toolkit of tunable parameters which can aid in advancing membrane technology.

Surface decoration of polyethylene terephthalate (PET) waste bottle-derived ultrafiltration membrane for enhanced lead ion removal and antifouling properties

PET waste bottle can be potentially used to create eco-friendly ultrafiltration (UF) membranes for water and wastewater treatment. The surface modification and functionalization of PET UF membrane offer opportunities to further heighten the performance of the membrane. In this study, phase inversion technique was used to fabricate PET UF membranes and PET/graphene oxide (GO) nanocomposite membranes through a facile GO suspension coating approach. The GO nanosheets were deposited on the PET UF membrane as a wavy and wrinkly layer. Using lead (Pb) ions and bovine serum albumin (BSA) feed solutions, the filtration performances of the neat PET and GO-PET membranes were evaluated. It was observed that, the Pb ions and BSA removal efficiencies were greatly enhanced by the surface decorated GO. Compared to neat PET, the 0.5GO-PET membrane exhibited improved flux performance by 188% and 61% for the removal of Pb ions and BSA, respectively. A high Pb ion removal of 100% and a BSA rejection of 97% were achieved by 0.5GO-PET membrane. The lower fouling tendency of 0.5GO-PET membrane during long-term filtration was attributed to the increased surface hydrophilicity and smoothness upon the deposition of GO layer. This study demonstrates a sustainable solution for efficient water treatment and heavy metal removal.

Preparation and Characterization of Polyethersulfone/Activated Carbon Composite Membranes for Water Filtration.

Ultrafiltration membrane technology holds promise for wastewater treatment, but its widespread application is hindered by fouling and flux reduction issues. One effective strategy for enhancing ultrafiltration membranes involves incorporating activated carbon powder. In this study, composite polyethersulfone (PES) ultrafiltration membranes were fabricated to include activated carbon powder concentrations between 0 and 1.5 wt.%, with carbon size fixed at 200 mesh. The ultrafiltration membranes were evaluated in terms of membrane morphology, hydrophilicity, pure water flux, equilibrium water content, porosity, average pore size, protein separation, and E-coli bacteria removal. It was found that the addition of activated carbon to PES membranes resulted in improvements in some key properties. By incorporating activated carbon powder, the hydrophilicity of PES membranes was enhanced, lowering the contact angle from 60° to 47.3° for composite membranes (1.0 wt.% of activated carbon) compared to the pristine PES membrane. Water flux tests showed that the 1.0 wt.% composite membrane yielded the highest flux, with an improvement of nearly double the initial value at 2 bar, without compromising bovine serum albumin rejection or bacterial removal capabilities. This study also found that the inclusion of activated carbon had a minor impact on the membrane's porosity and equilibrium water content. Overall, these insights will be beneficial in determining the optimal concentration of activated carbon powder for PES ultrafiltration membranes.

Investigation of the treatment and antibacterial properties of pollutant-containing water using black phosphorus blended polyethersulfone membranes (BP@PES)

The most important problem of membrane processes is clogging and therefore the reduction of their useful life. In order to eliminate such problems, the production of composite membranes is an option in membrane treatment systems. In this study, the usability of black phosphorus (BP) in membrane treatment systems, and its effect on antibacterial and treatment performance were studied. BP blended PES membranes (BP@PES) produced by loading BP into the polyethersulfone (PES) membranes were used for the treatment of bovine serum albumin (BSA) and Escherichia coli (E. coli). For this purpose, BP was added at three different amounts (0.5 %, 1.0 %, and 2.0 %) into PES membranes. Membranes with different BP amounts produced were named as 0.5%BP@PES, 1.0%BP@PES, and 2.0%BP@PES. After the production of these composite membranes, they were used in the dead-end filtration system and compared with the PES membrane without BP (bare PES). The removal effectiveness of bare PES was found to be 53.40 % in the BSA rejection results, and it was discovered to be 60.90 %, 97.15 %, and 100 % for 0.5%BP@PES, 1.0%BP@PES, and 2.0%BP@PES, respectively. The antioxidant activity of BP was 70.86% at 100 mg/L. Newly prepared BP caused single-strand DNA nuclease abilities at 50, 100, and 200 mg/L. BP showed the effective antimicrobial activity. The most antimicrobial activity was determined as a minimum inhibitory concentration (MIC) value of 8 mg/L against E. hirae and 100 % E. coli viability inhibition activity was achieved at 50 and 100 mg/L after 90 min exposure. BP also inhibited the biofilm formation of P. aeruginosa at 87.19 % and S. aureus at 90.28 % at 50 mg/L. Thus, both the effect of BP on membrane performance and its antibacterial properties were investigated. Pure water fluxes, BSA and E.coli rejection performances, and antibacterial properties of all membranes used in the membrane filtration system were investigated in detail. It is recommended to further investigate BP-containing membranes with different production techniques.

Novel polycarbonate/Fe3O4 nanocomposite membranes: Fabrication and performance evaluation in water treatment

AbstractIn this work, a novel polycarbonate (PC) nanocomposite membrane was prepared by incorporation of iron oxide (Fe3O4) nanoparticles using the nonsolvent induced phase separation method. The prepared membranes was applied in a submerged membrane system for bovine serum albumin (BSA) filtration through two cycles of 60 min. The properties and performance of fabricated membranes was characterized using water content, porosity, water contact angle, mechanical and thermal properties, membrane morphology including FESEM and AFM, antifouling performance, and BSA rejection. Results showed that by incorporation of Fe3O4 up to 0.5 wt.% in membrane, the hydrophilicity and porosity was increased and then decreased again by more nanoparticles concentration. DSC analysis indicated that Tg of membrane increased from 135.2 to 140.1°C when 0.5 wt.% of Fe3O4 was used. Also, the results of FESEM images revealed that addition of Fe3O4 nanoparticles significantly increased the number and pore size of membrane surface. According to AFM analysis, the membrane containing 0.5 wt.% showed smoother surface as compared to other membranes. Additionally, the PC/Fe3O4–0.5 membrane had better antifouling properties in term of high flux recovery ratio of 82.3% and 85% in the first and second cycles, respectively, while the neat PC membrane showed lower FRR of 70.4% and 74%.

Polysulfone ultrafiltration membranes fabricated from green solvents: Significance of coagulation bath composition

Even though membranes can lead to more environmentally sustainable separation processes, membrane casting typically involves toxic organic solvents. Recently, there has been increasing interest in substituting these toxic solvents for green solvents. In this study, polysulfone ultrafiltration membranes were fabricated by nonsolvent induced phase separation using two green, bio-derived solvents: Cyrene and gamma-valerolactone (GVL). The effect of coagulation bath composition was investigated, with water, ethanol, and water/ethanol mixtures tested as nonsolvents in the bath. Membranes were characterized and their performance was tested by dead-end filtration. For both Cyrene and GVL, using pure water in the coagulation bath resulted in membranes with residual solvent trapped inside. During dead-end filtration, these membranes were either impermeable (in the case of GVL) or had very low bovine serum albumin (BSA) rejection (in the case of Cyrene). Concentrations of ∼ 50–75 v% ethanol in the coagulation bath led to improved solvent removal and better pore formation, as indicated by scanning electron microscopy. These membranes also had higher flux and rejection. For example, membranes cast using Cyrene with a 65:35 volumetric ratio of ethanol:water in the coagulation bath achieved 70.1 L/m2/h water flux at 2.41 bar and 96.7 % BSA rejection. Additionally, the effect of humidity on membranes cast using GVL was investigated. Membranes cast under moderate humidity had novel surface morphologies with porous dimples ∼ 1 µm wide. Overall, these results show that Cyrene and GVL are promising solvents for preparing polysulfone ultrafiltration membranes. The work highlights the importance of relating membrane properties to casting conditions.

Effect of silver nanoparticles on the morphological, antibacterial activity and performance of graphene oxide-embedded polyvinylidene fluoride membrane

In this work, a different ratio of silver nanoparticles (Ag NPs) was used as a nanofiller on graphene oxide (GO)-embedded polyvinylidene fluoride (PVDF) membranes fabrication through a non-solvent induced phase separation method. The morphology of fabricated membranes was investigated using FTIR, XRD, and SEM-EDX techniques. The fabricated membranes were tested for Bovine Serum Albumin (BSA) rejection and Molecular Weight Cut Off (MWCO) with various initial concentrations of 100 – 400 ppm and 6 – 145 kDa, respectively using a crossflow method, as well as antibacterial activity against four strains bacteria via total plate counting and Kirby-Bauer method. The incorporation of hydrophilic GO and Ag NPs obviously alters membrane morphology, enhances membrane’s porosity and hydrophilicity. Moreover, it improves membrane crystallinity (> 70%) as indicated by the higher XRD peaks intensity. Based on the crossflow measurements, the membrane fabricated with GO and Ag ratio of 1: 3 (PVDF/GO/AgNPs – 3) demonstrated the highest BSA flux of 83.81 L/m2 h, which was third-fold higher than that of PVDF membrane as well as high BSA rejection (> 94%) and MWCO of ∼3 kDa. According to the observation, PVDF/GO/AgNPs – 3 also possessed a high bacteria killing ratio of > 94% and a large inhibition zone of ≥ 1.5 mm toward all bacteria strains. These results inferred that PVDF/GO/Ag membrane has great potential as antibiofouling membranes.

Multifunctional Ti3C2Tx MXene/Silver Nanowire Membranes with Excellent Catalytic, Antifouling, and Antibacterial Properties for Nitrophenol-Containing Water Purification.

The uncontrolled release of nitrophenol and dye pollutants into water systems is an increasingly serious worldwide concern, and thus efficient wastewater treatment technologies are urgently needed. Herein we report a novel two-dimensional (2D) transition metal carbides and/or nitrides (Ti3C2Tx MXene) membrane modified with silver nanowires (AgNWs) by vacuum assisted filtration technology for the ultrafast nitrophenol catalysis and water purification applications. Regular and controllable membrane transport channels were constructed by stacking Ti3C2Tx MXene nanosheets. Furthermore, the intercalation of AgNWs into the Ti3C2Tx MXene interlayer greatly enlarged the interlayer spacing, resulting in more gaps for fast and selective molecular transport. The optimized Ti3C2Tx MXene@AgNWs (M@A) membrane exhibited a water flux up to ∼191.9 L/(m2 h) while maintaining a high bovine serum albumin (BSA) rejection of ∼95.4%. We emphatically used M@A membranes as efficient catalysts for the reduction of 4-nitrophenol (4-NP), and the results indicated that M@A-12% membrane exhibited the greatest catalytic reduction ability, and recycling utilization. M@A-12% membrane also had an antibacterial rate of more than 99% against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). This work provides a possibility to expand the application of 2D multifunctional M@A membranes in wastewater treatment and pollutant catalytic degradation.

Preparation and performance evaluation of Polycarbonate/Polysulfone blend membranes for removal of Bovine serum albumin from water

ABSTRACT Blend membranes of polycarbonate and polysulfone were studied for removal of bovine serum albumin (BSA) from water. The membranes were prepared by blending (1–10) wt.% of polysulfone with polycarbonate and then non-solvent induced phase separation (NIPS) of blend solutions. Structural analysis, thermal and tensile properties, water uptake, porosity, water contact angle, and morphological studies were conducted. Water treatment performance of membranes were tested in a crossflow system in terms of pure water flux, rejection, and fouling. BSA rejection value was improved from 85.65% to 92.88% for polycarbonate membrane in the presence of 10 wt.% polysulfone.

Nanocelluloses fine-tuned polyvinylidene fluoride (PVDF) membrane for enhanced separation and antifouling

To mitigate membrane fouling and address the trade-off between permeability and selectivity, we fabricated nanocellulose (NC) fine-tuned polyvinylidene fluoride (PVDF) porous membranes (NC-PVDFs) using phase inversion method through blending NCs with varied aspect ratios, surface charges and grafted functional groups. NC-PVDF presented rougher surface (increased by at least 18.3 %), higher porosity and crystallinity compared to PVDF membrane. Moreover, cellulose nanocrystals incorporated PVDF (CNC-PVDF) elevated membrane surface charge and hydrophilicity (from 74.3° to 71.7°), while 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidized cellulose nanofibers modified PVDF (TCNF-PVDF) enhanced the porosity (from 25.0 % to 40.3 %) and tensile strength (63.6 % higher than PVDF). For separation performance, NC improved flux, rejection and fouling resistance due to facilitation of phase transition thermokinetics as pore-forming agent and increased hydrophilicity at both interface and pore wall. For water flux, NC-PVDFs (139–228 L·m−2·h−1) resulted in increased permeability compared to bare PVDF. CNC-PVDF membrane exhibited the highest water flux because of improved porosity, roughness and hydrophilicity. For bovine serum albumin (BSA) rejection, the removal rates of all NC-PVDFs were all above 90 %. Notably, TCNF-PVDF exhibited the most remarkable elevation of BSA rejection (95.1 %) owing to size exclusion and charge repulsion in comparison with PVDF.

Synthesis of PES membranes modified with polyurethane-paraffin wax nanocapsules and performance of bovine serum albumin and humic acid rejection.

Membrane fouling is a serious handicap of membrane-based separation, as it reduces permeation flux and hence increases operational and maintenance expenses. Polyurethane-paraffin wax (PU/PW) nanocapsules were integrated into the polyethersulfone membrane to manufacture a composite membrane with higher antifouling and permeability performance against humic acid (HA) and bovine serum albumin (BSA) foulants. All manufactured membranes were characterized by scanning electron microscopy (SEM), scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), and contact angle. The contact angle of the pristine polyethersulfone (PES) membrane was measured 73.40 ± 1.32. With the embedding of nanocapsules, the contact angle decreased to 64.55 ± 1.23 for PES/PU/PW 2.0 wt%, and the pure water flux of all composite membranes increased when compared to pristine PES. The pristine PES membrane also has shown the lowest steady-state fluxes at 45.84 and 46.59 L/m2h for BSA and HA, respectively. With the increase of PU/PW nanocapsule ratio from 0.5 to 1.0 wt%, steady-state fluxes increased from 51.96 to 71.61 and from 67.87 to 98.73 L/m2h, respectively, for BSA and HA. The results depicted that BSA and HA rejection efficiencies of PU/PW nanocapsules blended PES membranes increased when compared to pristine PES membranes.

Characterization of a chlorine resistant and hydrophilic TiO2/calcium alginate hydrogel filtration membrane used for protein purification maintaining protein structure

The development of membranes for protein purification has stringent requirement of disinfection resistance, low protein adsorption and anti-fouling, without changing protein structure. In this study, hydrophilic titanium dioxide (TiO2)/calcium alginate (TiO2/CaAlg) hydrogel membranes were prepared by a simple ionic cross-linking method. The effects of the porogenic agent polyethylene glycol (PEG) concentration, the molecular weight of PEG, and the concentration of TiO2 on the filtration properties were systematically investigated. The TiO2/CaAlg membrane exhibited excellent bovine serum albumin (BSA) rejection and anti-fouling properties. The mechanical properties and surface energy of the TiO2/CaAlg membrane were significantly improved. The chemical bonding mechanism of TiO2 and NaAlg was investigated by molecular dynamic simulation. The TiO2/CaAlg membrane had good chlorine resistance and could be disinfected or cleaned with sodium hypochlorite. The TiO2/CaAlg hydrogel membrane loaded with polyhydroxybutyrate (PHB) nanofibers maintained high flux (136.7 L/m2h) and high BSA rejection (98.0 %) at 0.1 MPa. The results of circular dichroism and synchronous fluorescence indicated that the secondary structure of BSA was maintained after membrane separation. This study provides one method for the preparation of green and environmentally friendly membrane for protein purification.

Efficient removal of dyes by light‐responsive graphene oxide‐blended polyethersulfone nanofiltration membranes

AbstractOne of the popular, low‐cost, efficient, and environmentally friendly methods for separating pollutants and water purification are membrane‐based processes. In this study, nanofiltration membranes were modified using the photo‐responsive graphene oxide‐spiropyran (GO‐SP) nanosheets as novel additive. Graphene oxide was employed to improve permeability, antifouling, and mechanical properties of the membranes. Spiropyran was added due to the increase in the self‐cleaning properties of the PES membranes. First, spiropyran (SP) as a photochromic compound was chemically immobilized onto the graphene oxide (GO) surface. Different examinations such as ultraviolet–visible (UV–Vis) spectroscopy, energy‐dispersive X‐ray spectroscopy (EDS), field emission scanning electron microscopy (FE‐SEM), and atomic force microscopy (AFM) were used to check the effective grafting of spiropyran. Then, nanofiltration membranes containing polyethersulfone (PES) and GO‐SP additive with different weight percentages (0.15, 0.25, 0.5, and 0.75 wt.%) were prepared. Membranes comprising 0.5 wt.% GO‐SP exhibited the best surface properties, and at concentrations above 0.5 wt.%, aggregation of GO‐SP additive occurred on the surface of the membrane. The Young modulus increased from 45.11 MPa for pure PES membrane to 82.63 MPa for PES/GO‐SP‐0.75. The flux of pure water, rejection of bovine serum albumin (BSA) protein, and separation of anionic dyes including Congo Red (CR) and Coomassie Brilliant Blue (CBB) were measured to show the filtration performance of the fabricated membranes. It was observed that the addition of 0.5 wt.% GO‐SP increased the flux of pure water of the PES‐based membrane from 2.97 to 14.6 L/m2 h. All prepared membranes rejected more than 94% of CBB and CR dyes. The addition of GO‐SP also developed the performance of the membranes against fouling. In addition, the effects of UV light on membrane fouling, dye rejection, and contact angle were investigated. According to the results, irradiation of GO‐SP with UV light decreased the contact angle and increased the flux of pure water. In the presence of UV light, the membrane containing 0.5 wt.% GO‐SP exhibited 58.74% reversible fouling, 8.30% irreversible fouling, and 93% flux recovery ratio, indicating its better performance than the pure membrane.

Effect of Copper Oxide Nanoparticles on the Performance of Polyvinyl Chloride Membranes

AbstractPolyvinyl chloride (PVC)/copper oxide (CuO) nanocomposite membranes were fabricated at different CuO nanoparticles loading levels using the phase inversion method. The fabricated membranes were tested through two filtration cycles in a submerged membrane system to remove bovine serum albumin (BSA) from water. Results showed that the hydrophilicity and porosity of the nanocomposite membranes were enhanced with an increase of CuO nanoparticles loading. The field emission electron microscopy images from the membrane surface demonstrated that the number and size of pores increased with addition of CuO nanoparticles. The atomic force microscopy test displayed that all nanocomposite membranes showed lower surface roughness in comparison to neat PVC membranes. The obtained results from membrane performance indicated that the irreversible fouling ratio for neat PVC membranes in the first and second cycles of filtration decreased for PVC/CuO‐1.5 membranes. Compared with the neat PVC membrane, the membrane containing CuO exhibited better capabilities such as the enhanced permeation flux, higher BSA rejection rate, and better antifouling properties.

Enhancing anti‐biofouling property by incorporating graphene oxide‐silver nanocomposite into polycaprolactone membrane for ultrafiltration application

AbstractBACKGROUNDThe control of biofouling is crucial in the membrane separation process. In the present study, graphene oxide‐silver (GO‐Ag) nanocomposite was fabricated and incorporated into polycaprolactone (PCL) membrane for the first time to increase its antibacterial properties and reduce its biofouling. Characterization of GO‐Ag nanocomposite was done by X‐ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier‐transform infrared (FTIR) spectroscopy. The PCL/GO‐Ag membranes were also characterized by XRD, attenuated total reflectance Fourier‐transform infrared (ATR‐FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), porosity determination, water contact angle measurement, and tensile test. Furthermore, pure water flux (PWF) and bovine serum albumin (BSA) rejection of the membranes were evaluated. Finally, the antibacterial activity of membranes was investigated by diffusion inhibition zone test and plate count of colony‐forming units.RESULTSThe results demonstrated that Ag nanoparticles were formed on the GO surfaces. In addition, membranes incorporated with the GO‐Ag nanocomposite were more hydrophilic, more porous, and more permeable to pure water while showing a lower protein rejection in the filtration of a BSA solution. Adding the GO‐Ag nanocomposite to the PCL membrane increased the inhibition effect against bacteria. The colony counting method confirmed that PCL/GO‐Ag membranes had higher antibacterial properties than the pure PCL membrane, and the PCL/1.8% GO‐Ag membrane represented the maximum antibacterial efficiency of 90% and 98% against P. aeruginosa and S. aureus, respectively.CONCLUSIONOverall, by the incorporation of GO‐Ag nanocomposite into the PCL membrane, PWF and antibacterial property were augmented, while protein rejection dropped. © 2023 Society of Chemical Industry.

Fouling minimization with nanofluidic membranes; How electric field may help

Researchers have given water purification substantial consideration in recent years as the availability of fresh water supplies has become a worldwide problem. Water treatment is the typical use for membranes. Enhancing membrane performance is thus a much sought after area of study. In this study, we examine a nanochannel that is embedded in a nanofluidic membrane, located between two reservoirs containing KCl electrolyte solution with equal concentrations. The neutral component present in the source reservoir is bovine serum albumin (BSA). A negatively charged polyelectrolyte layer coats the inside of the nanochannel, making the mass transfer more manageable and efficient. By applying an electric field and inducing electroosmotic flow, the electrolyte passes through the nanochannel without a change in concentration, while BSA is concentrated in the feed reservoir. Fouling performance was evaluated by measuring the flux of fluid passing through the nanochannel, the concentration difference CK+-CCl-, the electroosmotic velocity of the flow, and the time average volume flux. The BSA rejection was also monitored as a goal function. The difference between the electrolyte and the soft layer's physical–chemical properties was varied, and the parameters of electrolyte concentration, surface charge density of the soft layer, and type and frequency of the applied electric field, were all altered to determine their impact on membrane fouling. To do this, the Poisson-Nernst-Planck, continuity, and Navier-Stokes equations were numerically solved using the finite element method in an unsteady state. The findings demonstrate that fouling in the nanochannel can be reduced by increasing the charge density of the soft layer and lowering the electrolyte concentration. Using an AC field at intermediate frequencies is far more successful than a DC field in reducing fouling. Nevertheless, the AC field does not outperform the DC field in fouling reduction at either low or high frequencies tested.

Explication of polydopamine modified g-C3N4 as effective additive in PVDF nanocomposite membrane fabrication for enhanced ultrafiltration and self-cleaning performance

Nanocomposite membranes (NCMs) incorporated with nanomaterials have recently received increasing attention, but the preparation of high-performance membranes is still challenging due to the hydrophilicity and self-aggregation of the nanoparticles. In this study, graphite carbon nitride containing nitrogen defects was modified using dopamine (PDA@DCN) for effective alleviation of the agglomeration of nanoparticles resulting in a uniform casting solution. A non-solvent-induced phase separation method was adapted to prepare PVDF NCMs by using PDA@DCN as an effective additive. Superior permeability and selectivity were exhibited by the PDA0.25 @DCN/PVDF2 membrane (where a DA concentration of 0.25 g/100 mL was used in PDA@DCN preparation and 2% PVP was added during the membrane preparation) with the pure water flux of 390 L/(m2·h) and Bovine serum albumin (BSA) rejection of 95.9%. The extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory revealed that the improvement of the flux recovery rate of PDA0.25 @DCN/PVDF2 was due to the decreased attractive interaction for fouling. Ternary phase diagram and viscosity experiments confirmed that the addition of PDA0.25 @DCN accelerated phase inversion rate (as evident from thermodynamics and kinetics) and increased the porosity with smaller average surface pore size, which is expected to have good permeability and selectivity as an ultrafiltration membrane. Moreover, an excellent self-cleaning performance was demonstrated by PDA0.25 @DCN/PVDF2, with a flux recovery rate of 84.5%, simply under visible light irradiation, which indicates its potential for environment-friendly practical application.

Highly-selective hybrid ultrafiltration membranes with AlPO4-5 zeotype fillers: Effect of filler loading, morphology, and metal substitution on performance and fouling resistance

In recent years, membrane technologies have emerged as a promising solution for water treatment, particularly ultrafiltration. However, fouling remains a significant challenge in membrane applications, leading to a decline in membrane performance over time. To address this issue, the development of antifouling membranes has garnered considerable attention. By tuning their hydrophilicity, roughness, and surface charge, such membranes aim to mitigate fouling effects and extend their operational lifespan. In this work, aluminophosphate zeotype AlPO4-5 and cobalt-substituted AlPO4-5 (CoAPO-5) fillers were hydrothermally grown, their physicochemical, structural, and morphological characteristics were evaluated, and both types of fillers were incorporated into polyethersulfone (PES) membranes via phase inversion to fabricate antifouling hybrid ultrafiltration membranes. Fabrication of PES/xCoAPO-5 (y) hybrid membranes (x: Co/Al2O3 mole%, y: H2O/Al2O3 molar ratio in the synthesis mixture of the zeolite synthesis) was realized by varying the loading of the zeolite in the casting solution. Water permeance and bovine serum albumin (BSA) rejection of the developed hybrid membranes were significantly enhanced depending on the metal content, filler morphology, and loading within the membrane matrix. The maximum water permeance (688.8 L m−2 h−1 bar−1) was obtained for the membrane loaded with 6 wt% AlPO4-5 (400), which was 66 % higher than the pristine one, while a superior BSA rejection rate of 99.4 % was obtained from the membrane loaded with 6 wt% of 5CoAPO-5 (400).

Investigation of Photocatalytic PVDF Membranes Containing Inorganic Nanoparticles for Model Dairy Wastewater Treatment.

Membrane separation processes are promising methods for wastewater treatment. Membrane fouling limits their wider use; however, this may be mitigated using photocatalytic composite materials for membrane preparation. This study aimed to investigate photocatalytic polyvinylidene fluoride (PVDF)-based nanocomposite membranes for treating model dairy wastewater containing bovine serum albumin (BSA). Membranes were fabricated via physical coating (with TiO2, and/or carbon nanotubes, and/or BiVO4) and blending (with TiO2). Another objective of this study was to compare membranes of identical compositions fabricated using different techniques, and to examine how various TiO2 concentrations affect the antifouling and cleaning performances of the blended membranes. Filtration experiments were performed using a dead-end cell. Filtration resistances, BSA rejection, and photocatalytic cleanability (characterized by flux recovery ratio (FRR)) were measured. The surface characteristics (SEM, EDX), roughness (measured by atomic force microscopy, AFM), wettability (contact angle measurements), and zeta potential of the membranes were also examined. Coated PVDF membranes showed higher hydrophilicity than the pristine PVDF membrane, as evidenced by a decreased contact angle, but the higher hydrophilicity did not result in higher fluxes, unlike the case of blended membranes. The increased surface roughness resulted in increased reversible fouling, but decreased BSA retention. Furthermore, the TiO2-coated membranes had a better flux recovery ratio (FRR, 97%) than the TiO2-blended membranes (35%). However, the TiO2-coated membrane had larger total filtration resistances and a lower water flux than the commercial pristine PVDF membrane and TiO2-blended membrane, which may be due to pore blockage or an additional coating layer formed by the nanoparticles. The BSA rejection of the TiO2-coated membrane was lower than that of the commercial pristine PVDF membrane. In contrast, the TiO2-blended membranes showed lower resistance than the pristine PVDF membrane, and exhibited better antifouling performance, superior flux, and comparable BSA rejection. Increasing the TiO2 content of the TiO2-blended membranes (from 1 to 2.5%) resulted in increased antifouling and comparable BSA rejection (more than 95%). However, the effect of TiO2 concentration on flux recovery was negligible.