Neat Membrane Research Articles

Fabrication of nanocomposite membranes containing Ag/GO nanohybrid for phycocyanin concentration

In this research, silver/graphene oxide (Ag/GO) nanohybrid was first synthesized and used in production of polysulfone (PSF) ultrafiltration (UF) membranes via phase inversion method for concentrating phycocyanin (PC) and treating methylene blue (MB) dye effluent. Designing the experiment (DOE) using Box-Behnken method by Design Expert software helped to calculate the optimal values of the variables under study. The studied variables included PSF polymer concentration, polyvinyl pyrrolidone (PVP) pore-former concentration and Ag/GO nanohybrid content, which were investigated for their effects on pure water flux (PWF) and MB pigment rejection. According to the results of the DOE, the membrane containing 19.485 wt% PSF, 0.043 wt% PVP and 0.987 wt% Ag/GO was selected as the optimal membrane. Due to the high price of PC as drug, and the importance of removing MB pigment from the effluent of dyeing and textile industries, the membranes were first optimized with MB pigment and then the optimal membrane was used for concentrating PC. The results showed that PWF reaches from 40.05 L.m− 2.h− 1 (LMH) for the neat membrane to 156.73 LMH for the optimized membrane, which shows about 4 times improvement. Compared to the neat membrane, flux recovery ratio (FRR) of the optimized membrane increased by about 20% and its total fouling (Rt) decreased by about 10%. Also, the results showed that the optimized membrane can remove 81.6% of MB, as well as to reject 93.8% of PC.

The change in thermal-induced interchain distance boosts the gas barrier property of PEI-derived hollow fiber membranes

In order to fulfill diverse special applications (e.g. food packaging, anticorrosion coatings, flame retardant coatings, biomedical industry and lighter-than air applications), the superior gas barrier property is principal requirement. Based on previous researches, the gas barrier property of membranes could be improved to some extent by changing their component, chemical structure, physical property, fabrication parameters or incorporating impermeable fillers. The above-mentioned approaches provide the enhanced gas barrier property owing to increment in resistance for diffusion of tested gas. That implies the intrinsic factors of the membrane such as free volume fraction of membrane are determined effect on permeability to gas. Accordingly, present work investigated the impact of thermal treatment on enhancement of gas barrier property by manipulating the temperature in the range of 200 °C to 240 °C to adjust the orientation of molecular structure. Based on a series of analysis as well as pure gas measurement, the hydrogen permeability of as-treated membrane decreased by almost 2700 times than that of neat membrane, which is due to the absence of amorphousity. The exceptional gas barrier properties of resultant membrane exhibited great potential for special applications and paved the feasible way for other amorphous precursor to prepare the gas barrier membrane.

Fabrication of TiO2@ZIF-67 metal organic framework composite incorporated PVDF membranes for the removal of hazardous reactive black 5 and Congo red dyes from contaminated water

Novel application of TiO2@ZIF-67 composite incorporated poly (vinylidene fluoride) (PVDF) mixed matrix flat-sheet membranes for treating the water contaminated with hazardous reactive black 5 and congored dyes was the crux of this work. The composite was characterized by FTIR, BET, XRD, zeta potential and particle size, and TGA. The as-synthesized composite was embedded in the PVDF polymeric matrix and flat-sheet-membranes were fabricated adopting the NIPS method followed by the different characterizations like scanning electron microscopy, EDS, elemental mapping, contact angle, atomic force microscopy, surface energy, and XPS. Results of the performance studies showed an enhanced pure water permeability from 150.99 Lm-2h−1 for neat membrane to 261.39 Lm-2h−1 for TZM-2. The reactive black 5 dye was rejected in 97.4 %, 92.2 %, and 84.84 % in acidic, basic and neutral conditions respectively by TZM-2 membrane. Whereas, the PVDF membranes without the composite showed rejections of 83.19 %, 82.5 %, and 72.1 % respectively in acidic, basic, and neutral conditions. The Congo Red dye was rejected in 89.4 %, 95.68 %, and 92.4 % in acidic, neutral and basic conditions respectively by TZM-2 membranes. Whereas, the PVDF membranes without the composite showed rejections of 82.8 %, 91.9 %, and 85.4 % respectively in acidic, neutral and basic conditions.

Bilayer cellulosic FO membrane developed by polydopamine and nanochitosan through layer by layer coating process

A highly efficient bilayer cellulose acetate forward osmosis (FO) membrane was developed using polydopamine (PDA) and chitosan nanoparticles (CsNP) through layer by layer coating process and characterized using DLS, FESEM, AFM, EDX, and static contact angle. The use of CsNP and PDA led to an improvement in chemical properties, surface hydrophilicity, and structural parameter. The experimental tests for both RO and FO experiments were carried out to calculate structural parameter (it decreased from 0.59 mm for neat CA to 0.37 mm for CA-PDA/CsNP2) of membranes. Also, the salt rejection and water permeability of membranes were tested in RO mode using 40 mM NaCl, while the water flux and reverse salt flux of membranes were analyzed in FO test. The CA-PDA/CsNP2 membrane with 0.6 wt.% of CsNP in the coating solution not only showed a high water permeation flux about 21.23 LMH for 2 mM NaCl but also decreased its reverse salt flux from 7.08 to 4.52 gMH. According to the fouling test results, the normalized water flux of the neat membrane declined from 1 to about 0.65 while it was higher than 0.85 for CA-PDA/CsNP2 which represents an improvement in the antifouling property. This improvement was mainly due to an increase in the hydrophilicity of the coated membrane and the electrostatic repulsion among the foulant and surface of CA-PDA/CsNP2. The results showed that the fabricated CA-PDA/CsNP2 membrane shows a high potential application in the FO process and is more competitive than other existing FO membranes.

Application of modified PVC membranes with GO-ZnO nanoparticles in MBR: Sludge characteristics, fouling control and removal performance

BackgroundMembrane fouling is still one crucial impediment in the application of membrane bioreactors (MBR). MethodsAntifouling properties of GO and GO-ZnO embedded PVC membranes in MBR were investigated. ZnO nanoparticles were decorated onto GO nanosheets and then membranes were made by NIPS method. Significant findingsThe results revealed that the contact angle decreased from 80° for pure PVC to 67° for 0.1 wt% GO-ZnO embedded membrane. Pure water flux increased from 33 L/m2h for neat membrane to 128 L/m2h for 0.075 wt% PVC/GO-ZnO membrane. The performance of membranes was evaluated during 35 days MBR filtration system using several analyses including COD, turbidity, SMP, EPS, PSD, and EEM. Results indicated that the presence of GO-ZnO nanoparticles in the membranes has a positive effect on COD and turbidity removal due to the oxygen-containing groups attracting SMP through intermolecular force interaction. In addition, the inclusion of nanoparticles in the membranes leads to a reduction in EPS concentration. Research on PVC membranes with graphene oxide and zinc oxide nanoparticles in membrane bioreactor processes is crucial for advancing water treatment technology. These nanomaterials promise enhanced membrane performance, longevity, and efficiency in treating wastewater, leading to more sustainable and effective water treatment solutions.

Aminolysis-Based Zwitterionic Immobilization on Polyethersulfone Membranes for Enhanced Hemocompatibility: Experimental, Computational, and Ex Vivo Investigations.

Dialysis membranes are not hemocompatible with human blood, as the patients are suffering from the blood-membrane interactions' side effects. Zwitterionic structures have shown improved hemocompatibility; however, their complicated synthesis hinders their commercialization. The goal of the study is to achieve fast functionalization for carboxybetaine and sulfobetaine zwitterionic immobilization on PES membranes while comparing the stability and the targeted hemocompatibility. The chemical modification approach is based on an aminolysis reaction. Characterization, computational simulations, and clinical analysis were conducted to study the modified membranes. Atomic force microscopy (AFM) patterns showed a lower mean roughness for carboxybetaine-modified (6.3 nm) and sulfobetaine-modified (7.7 nm) membranes compared to the neat membrane (52.61 nm). The pore size of the membranes was reduced from values above 50 nm for the neat PES to values between 2 and 50 nm for zwitterionized membranes, using Brunauer-Emmett-Teller (BET) analysis. More hydrophilic surfaces led to a growth equilibrium water content (EWC) of nearly 6% for carboxybetaine and 10% for sulfobetaine-modified membranes. Differential scanning calorimetry (DSC) measurements were 12% and 16% stable water for carboxybetaine- and sulfobetaine-modified membranes, respectively. Sulfobetaine membranes showed better compatibility with blood with respect to C5a, IL-1a, and IL-6 biomarkers. Aminolysis-based zwitterionization was found to be suitable for the improvement of hemodialysis membranes. The approach introduced in this paper could be used to modify the current dialysis membranes with minimal change in the production facilities.

Fabrication optimization of polyethersulfone adsorptive mixed matrix membrane for enhanced dynamic methylene blue removal: Response surface methodology approach

AbstractIn the present study, the polyethersulfone (PES)/graphene oxide (GO)/polyethylene glycol 200 (PEG‐200) adsorptive mixed matrix membranes (AMMMs) were fabricated using a non‐solvent induced phase inversion method. According to the design of experiments using response surface methodology (RSM), PES concentration (15, 17.5, and 20%), PEG‐200 concentration as a pore former additive (0.5, 2.5, and 4.5%), and GO nanosheet loading percent (0, 0.5, and 1%) were varied during fabrication. A green solvent, dimethyl sulfoxide, was used as an alternative to conventional solvents, while it exhibited better membrane performance. Methylene blue (MB) removal was optimized in PES AMMM synthesis using RSM. Attenuated total reflectance Fourier transform infrared spectroscope confirmed the presence of GO functional groups in the optimum membrane. Scanning electron microscopy analysis revealed the optimum membrane was thicker than the neat membrane and atomic force microscopy analysis demonstrated higher surface roughness. The membranes hydrophilicity increased, with a decrease in water contact angle from 61.1 ± 0.2° (neat PES) to 54.4 ± 0.9° (optimal membrane). Pure water flux of 524.8 L m−2 h−1 and MB rejection of 97.46% were obtained for the optimum membrane. Furthermore, the optimum PES AMMM demonstrated a greater dynamic adsorption capacity in comparison to the unmodified PES membrane.Highlights The optimization of the polyethersulfone (PES) adsorptive mixed matrix membranes (AMMM) for methylene blue removal was performed utilizing the response surface methodology. The calculation of the dynamic adsorption capacity (DAC) was performed through the breakthrough curves. The integration of graphene oxide into the AMMM resulted in an enhanced DAC of the AMMM. The PES AMMM performance is based on Donnan electrostatic exclusion.

Gas‐Separating Metal‐Organic Framework Membrane Films on Large‐Area 3D‐Printed Tubular Ceramic Scaffolds

Polycrystalline metal‐organic framework (MOF) membrane films prepared on ceramic supports can separate gases with high energy efficiency. They generally exhibit very high permeance and selectivity but suffer from cost issues through the required ceramic supports. Increasing the area and reducing the ceramic component to a minimum can be a strategy to enabling neat membranes of MOFs. In a rapid prototyping approach using 3D‐printed porous scaffolds with a double‐helical channel geometry, an increased active membrane area‐to‐volume ratio is shown. Following stereolithographic printing and debinding of a ceramic slurry, an adapted sintering protocol is employed to sinter commercially available alumina slurries into porous scaffolds. The 3D‐printed scaffolds are optimized at a porosity of 40%, with satisfying mechanical stability. Furthermore, synthetic procedures yielding omnidirectional, homogeneous coatings on the outside and inside of the tubular scaffolds are developed. Membrane films of zeolitic imidazolate framework 8 and Hong Kong University of Science and Technology 1 covering a huge 50 cm2 membrane area are produced in this way by applying a counter‐diffusion methodology. Gas‐separation performance is evaluated for H2, CO2, N2, and CH4, in single‐gas measurements and on their binary‐gas mixtures.

Bi2WO6 nanoparticles anchored on membrane by grafting via in-situ polymerization for the treatment of antibiotic and pesticides wastewater

Antibiotics, natural organic matter, and pesticides are detected in the ecosystem's domestic water, surface water, and groundwater and are largely applied in pharmaceuticals and agriculture. Polymeric membranes are effectively remove the various pollutants in the water bodies, but fouling is one of the major limitations of commercial membranes. Herein, we modified the polymeric membrane surface with inorganic photocatalytic nanoparticles. In this work, the hydrothermal method is used for the synthesis of Bi2WO6 nanoparticles and as-synthesized nanoparticles grafted onto the various polymeric membranes, including polyetherimide (PEI), cellulose acetate (CA), polyvinylidene fluoride (PVDF), and polysulfone (PSF). The functional group studies confirmed the existence of nanoparticles and hydroxyl groups on the hybrid membrane. Further, finger-like voids, top-surface morphology, and roughness on the membrane surface were validated via Field Emission Scanning Electron Microscopy (FESEM) and Atomic force microscopy (AFM), respectively. The significant rejection of tetracycline, humic acid, and fulvic acid + atrazine was noted with the synthesized membranes in the following order: PVDF (81.1%, 78.8%, 80.6%) > CA (70.1%, 69.3%, 71.7%) > PSF (72.5%, 73.6%, 67.1%) > PEI (75.9%, 65.5%, 63.7%). The photodegradation efficiency of hybrid membranes against tetracycline, humic acid, and fulvic acid + atrazine was observed in the order: PEI (28.5%, 25.8%, 30.2%) < CA (46.5%, 42.4%, 40.5%) < PSF (46.9%, 37.7%, 44.7%) < PVDF (67.7%, 62.1%, 64.3%). These membranes exhibit an outstanding permeate flux recovery ratio to the neat membrane. Therefore, the grafting of Bi2WO6 nanoparticles creates a potential bonding with PVDF membranes than other polymeric membranes, thus exhibiting an outstanding rejection than hybrid and neat membranes.

Emulsified oil fouling resistant cellulose acetate-MoS2-nanocomposite membrane for oily wastewater remediation

This study evaluated the performance stability of amphiphilic cellulose acetate-MoS2-nanocomposite membranes (CMN) on oil removal and flux, oil fouling trends, as well as MoS2's catalytic peroxidase-like efficiency for oily wastewater treatment. When H2O2 was present in the feed, the membrane consistently achieved oil removal rates as high as 83.12 %, with only <10 % flux decline over an 80-minute filtration. During longer-term filtration of 4–6 h, the CMN membrane also exhibited significantly lower overall flux decline rates compared to the neat membrane with flux decline rates of 16.27 %, which was half of the cellulose membrane flux of 39.38 %. The fouling resistant performance was underpinned by the generation of reactive oxygen species (ROS) via catalytic reactions of MoS2 and H2O2. Coumarin was use as ROS scavenging agent and confirmed that the ROS amount was affected by the MoS2 and H2O2 dosages. The CMN membrane achieved the oil removal to the permissible discharge limit for low concentration wastewater. As a low-pressure membrane, it offered advantages of less energy consumption and continuously operating mode without frequent chemical cleaning and desorption. These findings support the CMN membrane's potential as a promising solution for treating industrial oily wastewater.

Simultaneously promoting CO2 permeability and selectivity of polyethylene oxide membranes via introducing CO2-philic KAUST-7

To overcome the challenging trade-off between permeability and selectivity in polymer CO2 separation membranes, CO2-philic metal-organic framework (MOF) KAUST-7 was incorporated within polyethylene oxide (PEO)-type matrices to prepare mixed matrix membranes (MMMs). A cross-scale approach of quantum chemical calculations and molecular dynamics simulations was used to explore the behavior and mechanism of CO2 adsorption on KAUST-7. The strong affinity between KAUST-7 and CO2 enabled a dramatic increase in the CO2 solubility of MMMs. The 2 wt% KAUST-7 loaded MMM exhibited CO2 permeability and CO2/N2 selectivity of 608 Barrer and 75, respectively, representing 41.7% and 54% improvement compared to the neat membrane, exceeding the 2019 upper bound. Furthermore, long-term separation tests for 100 h demonstrated the stability of these membranes.

Mixed matrix membranes based on NbOF52− anion-pillared porous MOFs for efficient CO2 separation

CO2 capture and storage technologies are crucial for environmental conservation and sustainable progress. To overcome the challenging trade-off between permeability and selectivity in polymeric CO2 separation membranes, we innovatively fabricated mixed matrix membranes (MMMs) by introducing three different NbOF52− anion-pillared porous metal–organic frameworks (MOFs), namely NbOFFIVE-2-Cu-i, NbOFFIVE-2-Ni-i, and NbOFFIVE-bpy-Ni. The CO2 capture performance of the three MOFs was investigated for the first time, and the ideal adsorption solution theory (IAST) method was used to predict the CO2 separation selectivity. Density functional theory (DFT) calculations confirmed that the interaction energy between NbOFFIVE-2-Cu-i and CO2 is the highest among the three MOFs. This is due to the optimal pore dimensions and strong Cδ+ … Fδ− electrostatic interaction between the C atoms in CO2 molecules and the F atoms in NOFFIVE-2-Cu-i. The introduction of the three MOFs into the MMMs led to an increase in CO2 solubility, resulting in enhanced CO2 permeability and selectivity. The MMM loaded with 2 wt% of NbOFFIVE-2-Cu-i exhibited exceptional CO2 permeability and CO2/N2 ideal selectivity values of 578 Barrer and 70, respectively, representing enhancements of 39 % and 29 % compared to neat membrane, and exceeding the upper bound established in 2019.

Fabrication of composite membrane with microcrystalline cellulose from lignocellulosic biomass as filler on cellulose acetate based membrane for water containing methylene blue treatment

A composite membrane based on cellulose acetate polymer with microcrystalline cellulose (MCC) based filler from lignocellulosic biomass is one of the right solutions to reduce methylene blue (MB) levels in water. MCC has been successfully isolated from water hyacinth, sengon wood, and kapok fiber with an alkalization method. The three MCCs have shown X-ray and FTIR diffraction patterns with characteristic peaks from cellulose and are stable up to 317 °C. Cellulose acetate (CA)/MCC membranes have been prepared using the phase inversion method and characterized by FTIR, tensile strength, contact angle, SEM, and porosity. The characterization results show that the addition of MCC can increase the tensile strength (3.05 N·mm-2), hydrophilicity (52°), and porosity (88 %). The CA/MCC membrane performed better than the neat membrane in separating MB. The composite membrane with MCC from kapok fiber showed optimum performance with increased flux and MB rejection up to 84 L·m−2·h−1 and 99 %, respectively.

Structure and performance of polyvinylchloride microfiltration membranes improved by green silicon oxide nanoparticles for oil-in-water emulsion separation

Oil-in-water (O/W) emulsion separation has received wide attention in the field of industrial water treatment. Mixed matrix polyvinylchloride (PVC) membranes containing 0.1–1.5 wt% silicon oxide (SiO2) as an inorganic additive obtained from two different sources were fabricated via the phase inversion method. The impact of embedding SiO2 in the PVC texture was studied by making a comparison between SiO2 nanoparticles prepared from common water reeds as a bio-source (namely bio SiO2) and commercial SiO2. The fabricated membranes were characterized via Fourier-transform infrared spectroscopy, field emission scanning electron microscope, and atomic force microscopy. Also, the water contact angle and water flux were measured. The results of the water contact angle revealed that modification of the PVC membrane by 0.5 wt% bio SiO2 reduced the contact angle from 82.3° for the neat PVC membrane to 29.7° showing that high enhancement in the membrane's hydrophilicity. The effect of oil feed concentrations (100–1000 mg/L) and temperature (25, 35, and 45 °C) on the treatment efficiency and permeate flux was investigated at trans-membrane pressures (1.5, 2.5, and 3.5 bar). The results showed that the permeation flux of the modified membranes was higher than that of the neat membrane due to enhancing the membrane's properties. Finally, the membranes were evaluated in a crossflow system with simulated O/W emulsion as a feed. The bio SiO2/PVC membranes have applicable potential in the oily wastewater treatment for their low price, good antifouling performance, and high removal efficiencies of NTU (over 98.15 %), COD (up to 99.19 %) for a membrane containing 0.5 wt% bio SiO2 used for 100 mg/L O/W emulsion.

A CFD simulation and experimental study: The impact of aerator design on the bubble flow pattern, foulant removal and scouring capability of flat sheet membrane bioreactor (FSMBR)

Membrane fouling is a main drawback of membrane bioreactor systems. Moreover, optimization of influential parameters via practical analyses is tedious and time-consuming. Therefore, the CFD-RSM approach accompanied by experimental results was employed to propose the optimal aerator design. In comparison with the linear nozzles, simulation results proposed that at equal air flow rate, the angular nozzle aerators with 30° toward the surface of the membrane could provide higher amounts of surface tension, air scouring capabilities as well as air volume fraction at a similar air flow. Simulation findings were experimentally validated using a bench-scale MBR system. Obtained results showed that the irreversible fouling ratio to the total fouling ratio for neat membrane was decreased from 62.99 % to 43.97 % for linear and angular nozzles, respectively. This improvement in the nozzle performance was more pronounced for nanocomposite membranes, in which the abovementioned ratio was decreased from 43.44 % to 24.57 %. It is confirmed that the impact of nozzle design on the nanocomposite membrane was 30.48 % higher than that of the neat membrane. Specific aeration demand (SADm) value was decreased from 0.77 to the 0.49 [Nm3/(m2h)] at an equal amount of shear stress and lower inlet velocity, when linear nozzles were replaced by the angular nozzles. The lower SADm and better foulant capability leads to the optimal operation condition and lower energy as well as operating costs.

Effect of incorporation of multi-walled carbon nanotubes on the CO2/CH4 separation performance of sulfonated poly (ether ether ketone) / polyetherimide composite membranes using design of experiments and molecular dynamics simulation methods

Blend membranes were prepared based on sulfonated poly (ether ether ketone) (SPEEK) and poly (etherimide) (PEI) using different amounts of multi-wall carbon nanotubes (MWCNTs) (up to 2 wt%). PEEK has been sulfonated directly to reach 70 % degree of sulfonation. The manufactured membranes were examined by X-ray diffraction (XRD), scanning field emission electron microscopy (FESEM), Fourier transformed infrared spectroscopy (FTIR). The effect of the composition of SPEEK / PEI on membrane selectivity was investigated under different feed pressures (2 to 8 bar) and temperatures (25 to 55 °C). The values of selectivity and gas permeability were varied between the value of the individual polymers, fluctuating systematically with SPEEK / PEI content variation in the blends. TGA and tensile tests result obtained for prepared membranes shown that the hybrid membrane had good thermal and mechanical properties. The addition of MWCNTs to the blend led to simultaneously improve the selectivity and permeability of the pair gases of CO2 and CH4. The permeability of CO2, as well as CH4/CO2 selectivity for the membrane with the same weight of SPEEK and PEI, and 1 wt% of MWCNTs (coded SP55M1) experienced an increase of about 22 % compared with the neat membrane. Molecular dynamics simulations (MDS) were performed by employing the COMPASS force field to estimate the diffusivity of CH4 and CO2 gases through selected membranes. At last, with compared to the obtained experimetal data, the optimized nanocomposite membrane, integrated with MWCNTs was efficient, which makes it promising platform to separate mixed gase flows of CO2 and CH4 and other related environmental processes.

Exploring the effect of aeration intensity on a modified PVDF-PEG membrane incorporated with nano-MgO: antifouling and AnT-POME treatment

ABSTRACT Aeration effects on membrane filtration of wastewater remain partially explored, as lesser or excessive application often aggravates the fouling. Furthermore, most polymeric membranes are hydrophobic, which facilitates the deposition of foulants and layer formation. There is a need for further investigation on the use of aeration and membrane modifications with a better antifouling property. This study focused on investigating the influence of aeration intensity on the antifouling performance of a modified co-polymerized polyvinylidene-fluoride (PVDF-PEG) fiber using a hydrophilic nano-MgO to treat anaerobically digested palm oil mill effluent (AnT-POME). The aeration intensity was varied to three levels (3,4,5Lmin-1). Both neat and modified membranes obtained their best AnT-POME permeate flux at 4Lmin-1 with a relatively stable value of 28.67 and 89.85 Lm-2 h-1 after 5 h filtration, respectively. The irreversible fouling percentage (IFP) for the neat and modified membrane at 4Lmin-1 aeration intensity, was 66.67% and 12.42%, respectively. This indicates that the neat membrane is more susceptible to fouling. To investigate the changes in the membranes, the fouled membranes were characterized using SEM, FTIR and porosity, then compared with that of the pristine samples. Cake-scaly layers were noticed on the neat membrane. Additionally, both membranes successfully reduced the COD, TDS, TSS, and TN above 60%.

Hydrophilic polydopamine/polyvinylpyrrolidone blended polyphenylsulfone hollow fiber membranes for the removal of arsenic-V from water

The demand for fresh drinking water is sky rocketing with the world's increasing population, urbanization and various industrial growth. However, toxic heavy metals and metalloids like arsenic is contaminating the drinking water. Arsenic is poisonous, carcinogenic and mutagenic for millions of population. We hereby proposing in-house fabricated novel hollow fiber membranes using polyphenylsulfone (PPSU) and pore-forming agent polyvinylpyrrolidone (PVP) along with increased concentrations of bio-inspired hydrophilic additive polydopamine (PDA) for removal of arsenic-V from the drinking water. The crystallinity of PDA was interpreted by X-ray diffraction. The morphology, topology and membrane surface chemistry of fabricated membranes were evaluated by scanning electron microscopy, atomic force microscopy, thermogravimetric analysis, fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy. The results indicated that, for the PDA-contained membranes overall performance was increased in terms of membrane hydrophilic characteristics and rejection efficacy. A 3 wt% of PDA in PPSU/PVP (PDA-3) executed enhanced arsenate (As-V) removal as high as 87.15% with flux of 31.80 L/m2h, which was higher than the neat membrane (PDA-0) as 67.70% with flux of 15.07 L/m2h for 5 mL/L arsenic-V aqueous solution at 0.2 MPa transmembrane pressure. Improved antifouling properties were observed from PDA-contained hollow fiber membranes, as evidenced by the improved flux recovery ratio and superior thermal stability. The mechanical properties (tensile strength) of pristine and PDA-contained membranes was also investigated.

Integration of Porous Nanomaterial-Infused Membrane in UF/FO Membrane Hybrid for Simulated Osmosis Membrane Bioreactor (OsMBR) Process

This study explored the use of a combination of hydrothermal and sol–gel methods to produce porous titanium dioxide (PTi) powder with a high specific surface area of 112.84 m2/g. The PTi powder was utilized as a filler in the fabrication of ultrafiltration nanocomposite membranes using polysulfone (PSf) as the polymer. The synthesized nanoparticles and membranes were analyzed using various techniques, including BET, TEM, XRD, AFM, FESEM, FTIR, and contact angle measurements. The membrane’s performance and antifouling properties were also assessed using bovine serum albumin (BSA) as a simulated wastewater feed solution. Furthermore, the ultrafiltration membranes were tested in the forward osmosis (FO) system using a 0.6-weight-percent solution of poly (sodium 4-styrene sulfonate) as the osmosis solution to evaluate the osmosis membrane bioreactor (OsMBR) process. The results revealed that the incorporation of PTi nanoparticles into the polymer matrix enhanced the hydrophilicity and surface energy of the membrane, resulting in better performance. The optimized membrane containing 1% PTi displayed a water flux of 31.5 L/m2h, compared to the neat membrane water value of 13.7 L/m2h. The membrane also demonstrated excellent antifouling properties, with a flux recovery of 96%. These results highlight the potential of the PTi-infused membrane as a simulated osmosis membrane bioreactor (OsMBR) for wastewater treatment applications.

Surface modification of PVDF membrane via layer-by-layer self-assembly of TiO2/V for enhanced photodegradation of emerging organic pollutants and the implication for wastewater remediation

Herein, we present a novel polyvinylidene fluoride/vanadium-titanium dioxide (PVDF-TiO2/V) membranes prepared using LBL self-assembly. The membranes were tested for ultrafiltration of bovine serum albumin solution and photodegradation of SMX solution. The neat PVDF membrane was endowed with photocatalytic function due to the synergistic interaction of TiO2 and V. The structure and morphology of PVDF-TiO2/V membranes were characterized using a variety of techniques, showing that TiO2/V particles had been successfully integrated on the membrane surface. By increasing the number of TiO2/V layers, contact angle tests demonstrated that the membranes hydrophilicity has been significantly improved. The FTIR result demonstrated that the TiO2/V was affixed to the surface of the PVDF membrane by interfacial interactions. The thermal property of the PVDF membrane was also improved with the assembly of TiO2/V on the membrane surface. The PVDF-TiO2/V membranes maintained a high BSA rejection of 99.4 % and FRR of 97.4 % while showing a water flux up to 390.07 kg m-2h−1, which is ∼1.5 times higher than that of neat PVDF membrane. Specifically, the membranes were capable of degrading SMX under visible-light. The photocatalytic activity for SMX increased with the number of TiO2/V layers, attaining the highest value with four self-assembled TiO2/V layers. The reaction rate of the optimum membrane was 11.57-fold compared to the neat membrane under visible-light. Furthermore, 95.9 % degradation efficiency was achieved, even after six cycles. More importantly, BPA, MO, and MB could be photodegraded using the PVDF-TiO2/V membranes. Compared to using bulk or powdered photocatalysts, the PVDF-TiO2/V membrane is more practical and promising for wastewater remediation due to its many advantages including better long-term stability, ability to endure pollutant degradation, low cost, and environmentally friendly.