PPSU Membrane Research Articles

Fabrication of 2D Vanadium MXene Polyphenylsulfone Ultrafiltration Membrane for Enhancing the Water Flux and for Effective Separation of Humic Acid and Dyes from Wastewater.

MXene, a new 2D transition metal carbide-based material, is gaining outstanding attention in recent days in the area of separation and purification. In this study, we have successfully synthesized vanadium-based MXene-V2CT x (where T represents functional groups such as -OH, O, and F) by etching an aluminum layer from V2AlC. For the first time, a vanadium-based MXene-V2CT x -embedded mixed matrix membrane was fabricated and utilized for removal of hazardous dye and humic acid from wastewater. With an increase in V2CT x loading, the hydrophilicity of the polyphenylsulfone (PPSU) membrane reasonably improved, and its water contact angle was reduced from 82.8 to 70.9°. V2CT x nanosheet-embedded PPSU membrane exhibited an excellent pure water permeability of 247 L m-2 h-1, which was 266% elevated than the pristine PPSU membrane. The V2CT x -PPSU membrane revealed a good antifouling nature, thermal stability, and 98.5% removal of humic acid. The optimal membrane exhibited 96.6 and 82.02% expulsion of Reactive Black 5 (RB 5) dye and Reactive Orange 16 (RO 16) dye, respectively. The flux for RO 16 and RB 5 dyes and humic acid were remarkable with a value of 202.02, 161.61, and 141.41 L m-2 h-1, respectively. This work provides a new V2CT x -incorporated PPSU ultrafiltration membrane to effectively treat humic acid and dye wastewater.

Mussel-inspired fabrication of fouling-resistant PPSU-based nanocomposite membrane using polydopamine and tannic acid-functionalized CeO2 nanoparticles towards effective oil-water emulsions separation

Surface modification of membranes using hydrophilic nanoparticles has proved promising to improve the surface wettability and antifouling properties of the membranes that are otherwise prone to the attachment of oil droplets. Nonetheless, the strong adhesion of nanoparticles onto the membrane surface and their long-term performance pose problems for their widespread application. To address these issues, a novel organic-inorganic hybrid coating was constructed onto surfaces of polyphenylsulfone (PPSU) ultrafiltration membrane via simultaneous deposition of mussel-inspired polydopamine (PDA) followed by immobilization of tannic-acid functionalized cerium oxide (CeO2) nanoparticles. These prepared membranes were characterized by FTIR, XPS, FESEM, EDX, pore size, water contact angle (WCA), underwater oil contact angle (UOCA), and separation performance. The effects of functionalization and nanoparticle concentration on membrane properties were investigated. SEM and EDX results showed that functionalized nanoparticles (up to optimum concentration: 0.05 wt%) were uniformly distributed onto the membrane surface, which exhibited increase in permeate flux (∼375 %), UOCA (∼36 %), Fouling resistance ratio (FRR ∼ 300 %) with a decrease in irreversible fouling (∼94 %) and WCA (∼80 %) and high oil rejection of > 99 % compared to pristine PPSU membrane. Long-term operation (for six cycles) indicates that the optimum membrane possessed high efficiency and durability for oil-in-water emulsion separation due to superb antifouling properties and strong binding of the functionalized nanoparticles onto the membrane surface.

Development and characterization of porous membranes based on PPSU/PES using polyethylene glycol as porogen: Application for cobalt removal by polyelectrolyte‐enhanced ultrafiltration

AbstractBACKGROUNDIn this work, a polyphenylsulfone/polyethersulfone (PPSU/PES) composite membrane was successfully prepared using the phase‐inversion method in the presence of polyethylene glycol (PEG) as a hydrophilic additive. The effect of concentration of PEG (0, 2, 4 and 6 wt%) was investigated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and contact angle analysis.RESULTSThe obtained results confirmed that the morphology and hydrophilicity of the porous membrane varied with the addition of PES as reinforcing agent and the PEG concentration as porogen. SEM results confirmed that the membranes obtained have a high permeability with a finger‐shaped structure and that the size and density of the pores increase with an increase in the incorporated PEG. The contact angle was decreased and the porosity of the PPPn blend membranes was increased from 16.06 for the neat PPSU membrane to 385.3 L h−1 m−2 bar−1 for the PPP6 membrane. A strong interaction between the components (PPSU, PES and PEG) was revealed by FTIR spectroscopy and TGA.CONCLUSIONThe filtration results showed that PPP2 is the better formulation of the dope suspension in the range of ultrafiltration membranes in terms of flux (179.3 L h−1 m−2 bar−1) and bovine serum albumin retention (94%). The application of polyelectrolyte‐enhanced ultrafiltration using polyethylenimine (PEI) for the removal of cobalt ions afforded high removal rates (92.5%). The optimal performances were obtained at pH ≥ 4, transmembrane pressure of 4 bar and 1200 ppm of PEI. © 2023 Society of Chemical Industry (SCI).

Hybrid membranes of polyphenylsulfone/functionalized MXene nanosheets for the pervaporation dehydration of acetone and isopropyl alcohol

AbstractThe resistance of pervaporation (PV) dehydration membranes to organic solvents is of great importance. Polyphenylsulfone (PPSU) is known to resist most organic media; however, its acetone dehydration performance has not been evaluated yet. In the present study, MXene hydrophilic nanosheets with hydroxyl functional groups were synthesized and then incorporated in the PPSU membrane to prepare the PPSU/MXene PV membrane for the first time. The prepared membranes were used in the dehydration of acetone/water and isopropyl alcohol (IPA)/water. By comparing the attenuated total reflectance Fourier transform infrared spectroscopy spectra of the pure membrane and the nanocomposite membrane, the incorporation of hydroxyl functional groups into PPSU via MXene loading was confirmed. MXene improved the hydrophilicity and tensile properties of the membrane. The separation factor in acetone dehydration dropped with MXene incorporation up to 1 wt% and then increased with further MXene loading; however, it stayed almost unchanged in IPA dehydration with adding 0.5, 1, and 1.5 wt% MXene to the membrane. Incorporating 1 wt% MXene, the pervaporation separation index (PSI) was improved by 5.8 times in acetone dehydration and 9.7 times in IPA dehydration. The PPSU/1 wt% MXene membrane provided a remarkably higher separation factor (261 vs. 136) and PSI (99 vs. 58 kg/m2h) in acetone dehydration than in IPA dehydration; however, total flux was slightly lower in acetone dehydration (0.38 vs. 0.43 kg/m2h). This study implies that PPSU/MXene is a promising membrane material for the PV dehydration of organics.Highlights MXene hydrophilic nanosheets were synthesized. The synthesized MXene was loaded into the polyphenylsulfone membrane. PPSU/MXene membranes were used in pervaporation dehydration. MXene improved the hydrophilicity and tensile properties of the membrane. PPSU/MXene is a promising membrane material for PV dehydration of organics.

Novel MXene-Modified Polyphenyl Sulfone Membranes for Functional Nanofiltration of Heavy Metals-Containing Wastewater

In this work, MXene as a hydrophilic 2D nanosheet has been suggested to tailor the polyphenylsulfone (PPSU) flat sheet membrane characteristics via bulk modification. The amount of MXene varied in the PPSU casting solution from 0-1.5 wt.%, while a series of characterization tools have been employed to detect the surface characteristics changes. This included atomic force microscopy (AFM), scanning electron microscopy (SEM), contact angle, pore size and porosity, and Fourier-transform infrared spectroscopy (FTIR). Results disclosed that the MXene content could significantly influence some of the membranes' surface characteristics while no effect was seen on others. The optimal MXene content was found to be 0.6 wt.%, as revealed by the experimental work. The roughness parameters of the 0.6 wt.% nanocomposite membrane were notably enhanced, while greater hydrophilicity has been imparted compared to the nascent PPSU membrane. This witnessed enhancement in the surface characteristics of the nanocomposite was indeed reflected in their performance. A triple enhancement in the pure water flux was witnessed without compromising the retention of the membranes against the Cu2+, Cd2+ and Pd2+ feed. In parallel, high, and comparable separation rates (>92%) were achieved by all membranes regardless of the MXene content. In addition, promising antifouling features were observed with the nanocomposite membranes, disclosing that these nanocomposite membranes could offer a promising potential to treat heavy metals-containing wastewater for various applications.

Enhanced Antifouling in Flat-Sheet Polyphenylsulfone Membranes Incorporating Graphene Oxide-Tungsten Oxide for Ultrafiltration Applications.

In this study tungsten oxide and graphene oxide (GO-WO2.89) were successfully combined using the ultra-sonication method and embedded with polyphenylsulfone (PPSU) to prepare novel low-fouling membranes for ultrafiltration applications. The properties of the modified membranes and performance were investigated using Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), contact angle (CA), water permeation flux, and bovine serum albumin (BSA) rejection. It was found that the modified PPSU membrane fabricated from 0.1 wt.% of GO-WO2.89 possessed the best characteristics, with a 40.82° contact angle and 92.94% porosity. The permeation flux of the best membrane was the highest. The pure water permeation flux of the best membrane showcased 636.01 L·m-2·h-1 with 82.86% BSA rejection. Moreover, the membranes (MR-2 and MR-P2) manifested a higher flux recovery ratio (FRR %) of 92.66 and 87.06%, respectively, and were less prone to BSA solution fouling. The antibacterial performance of the GO-WO2.89 composite was very positive with three different concentrations, observed via the bacteria count method. These results significantly overtake those observed by neat PPSU membranes and offer a promising potential of GO-WO2.89 on activity membrane performance.

Development of High Flux Nanocomposite Polyphenylsulfone/Oxidized Multiwalled Carbon Nanotubes Membranes for Ultrafiltration Using the Systems with Critical Solution Temperatures.

The study deals with the investigation of the effect of the modification of polyphenylsulfone (PPSU) flat sheet membranes for ultrafiltration using oxidized multiwalled carbon nanotubes (O-MWCNT) in order to enhance membrane permeability and antifouling performance. The effect of O-MWCNT loading to the PPSU-polyethylene glycol (PEG-20,000, Mn = 20,000 g·mol−1)-polyvinylpyrrolidone (PVP K-30, Mn = 40,000 g·mol−1)-N-methy-2-pyrrolidinone (NMP) colloid systems on the phase state and viscosity was studied. It was found that PPSU-PEG-20,000-PVP K-30-O-MWCNT-NMP colloid systems feature a gel point (T = 35–37 °C) and demixing temperature (T = 127–129 °C) at which two bulk phases are formed and a polymer system delaminates. According to the study of the phase state and viscosity of these colloid systems, a method for the preparation of high flux PPSU membranes is proposed which includes processing of the casting solution at the temperature higher than gel point (40 °C) and using a coagulation bath temperature lower than gel point (25 °C) or lower than demixing temperature (40 °C and 70 °C). Membrane structure, topology and hydrophilic-hydrophobic balance were investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM) and water contact angle measurements. The effect of coagulation bath temperature and O-MWCNT concentration on the membrane separation and antifouling performance in ultrafiltration of human serum albumin and humic acids solutions was studied. It was found that the modification of PPSU ultrafiltration membranes by O-MWCNTs yielded the formation of a thinner selective layer and hydrophilization of the membrane surface (water contact angle decreased from 53–56° for the reference PPSU membrane down to 33° for the nanocomposite membrane with the addition of 0.19 wt.% O-MWCNT). These changes resulted in the increase in membrane flux (from 203–605 L·m−2·h−1 at transmembrane pressure of 0.1 MPa for the reference membrane up to 512–983 L·m−2·h−1 for nanocomposite membrane with the addition of 0.19 wt.% O-MWCNT depending on coagulation bath temperature) which significantly surpasses the performance of PPSU ultrafiltration membranes reported to date while maintaining a high level of human serum albumin rejection (83–92%). It was revealed that nanocomposite membrane demonstrated better antifouling performance (the flux recovery ratio increased from 47% for the reference PPSU membrane up to 62% for the nanocomposite membrane) and higher total organic carbon removal compared to the reference PPSU membrane in humic acids solution ultrafiltration.

Removal of protein, histological dye and tetracycline from simulated bioindustrial wastewater with a dual pore size PPSU membrane

Wastewater from production of active pharmaceutical ingredients (APIs) often contains proteins, azo dyes or antibiotics, which cause severe water eutrophication and growth of drug-resistant bacteria. A series of polyphenylsulfone (PPSU) membranes was prepared to determine the relationships between pore structures and the abilities of different membranes to separate foulants, and the characteristics and performance of the ultrafiltration membranes were investigated. The structure of the skin layer and the cross-sectional texture were converted from dense and finger-like macrovoids to porous sponge shapes because of a delayed liquid–liquid (L-L) demixing time. Formation of novel PPSU membranes via noncovalent bonding interactions was evaluated, and this selectively affected the membrane surface pore structure, layer thickness, surface polarity and electronic repulsive force. All PPSU membranes demonstrated excellent rejection of organic foulants, including bovine serum albumin (BSA) (~100% rejection) and acid red 1 (AR1) (~90% rejection). Additionally, M5 provided an excellent tetracycline (TC) rejection efficiency of 89% in the 1st cycle. Due to the small size of TC, pore size effects were displayed. Moreover, the pure water flux recovery rate (FRR) increased from 85% (M1, water/ethanol: 100/0) to 99.9% (M4, water/ethanol: 30/70) after BSA filtration because the weak nonsolvent decreased the roughness of the membrane surface, and the membrane made with added EtOH yielded excellent FRR values (99.9%) after AR1 filtration. Therefore, PPSU membranes successfully achieved over 90% rejection of organic foulants and excellent FRRs, indicating that they may be suitable for purifying wastewater from API plants that generate organic foulants with a wide range of sizes.

Recent Advancements in Polyphenylsulfone Membrane Modification Methods for Separation Applications.

Polyphenylsulfone (PPSU) membranes are of fundamental importance for many applications such as water treatment, gas separation, energy, electronics, and biomedicine, due to their low cost, controlled crystallinity, chemical, thermal, and mechanical stability. Numerous research studies have shown that modifying surface properties of PPSU membranes influences their stability and functionality. Therefore, the modification of the PPSU membrane surface is a pressing issue for both research and industrial communities. In this review, various surface modification methods and processes along with their mechanisms and performance are considered starting from 2002. There are three main approaches to the modification of PPSU membranes. The first one is bulk modifications, and it includes functional groups inclusion via sulfonation, amination, and chloromethylation. The second is blending with polymer (for instance, blending nanomaterials and biopolymers). Finally, the third one deals with physical and chemical surface modifications. Obviously, each method has its own limitations and advantages that are outlined below. Generally speaking, modified PPSU membranes demonstrate improved physical and chemical properties and enhanced performance. The advancements in PPSU modification have opened the door for the advance of membrane technology and multiple prospective applications.

The effects of TiO2 nanoparticles and polydopamine on the structure, separation, and antifouling properties of PPSU membrane

ABSTRACT One of the most efficient and cost-effective technologies for removing dye pollutants from industrial effluents is membrane separation. This study aims to investigate the effect of modified nanocomposite polyphenylsulfone (PPSU) membrane for removing Direct Orange102 (DO) dye from aqueous solutions. For this purpose, the PPSU membrane was surface modified by polydopamine (PPSU/PD) to improve its hydrophilic properties and separation performance. Then, a nanocomposite membrane, PPSU/PD/TiO2, was prepared by coating the surface of PPSU/PD with different dosages of TiO2 nanoparticles. The prepared PPSU/PD and PPSU/PD/TiO2 samples were characterized by employing attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and contact angle measurements. The ATR-FTIR analysis and FESEM images indicated that polydopamine and TiO2 were successfully coated on the surface of the membranes. Also, the results showed an increment in the hydrophilicity and roughness of the membrane after the addition of TiO2 nanoparticles. The performances of the fabricated membranes were compared in the separation of DO dye, Na2SO4, and bovine serum albumin (BSA). The best flux and rejection were obtained at 2 mg/ml of dopamine and 0.03 wt% of TiO2 loading. The prepared PPSU/PD/TiO2 membrane with high water flux provided impressive salt and dye removal. The results revealed that dye rejection increased from 80.5% for the PPSU membrane to 90% for the PPSU/PD membrane with a flux of 36 Lm−2h−1. For the PPSU/PD/TiO2 membrane, dye rejection and flux improved to 96.8% and 82 Lm−2h−1, respectively. The incorporation of TiO2 nanoparticles and polydopamine on the PPSU membrane surface enhanced the flux recovery ratio (FRR%) from 60.2% to 87%. The results of this study confirmed that modification of PPSU membrane by polydopamine and TiO2 nanoparticles leads to the improvement of the antifouling behavior and separation performance of the fabricated membrane toward the DO dye removal from aqueous solutions.

Hydrophilic nano-aluminum oxide containing polyphenylsulfone hollow fiber membranes for the extraction of arsenic (As-V) from drinking water

In the present work, hollow fiber ultrafiltration membranes were fabricated by incorporating intensified dosages of nano‑aluminum oxide (nano-Al2O3; 0.6 wt%, 1.0 wt% and 1.5 wt%) into cellulose acetate (CA)/polyphenylsulfone (PPSU) and cellulose acetate phthalate (CAP)/PPSU by non-solvent induced phase separation (NIPS) process. The topological structures and the morphologies were investigated using atomic force microscope (AFM) and scanning electron microscope (SEM). The crystalline and morphological structures of the nano-Al2O3 were investigated using X-ray diffraction (XRD) and transmission electron microscope (TEM) respectively. Fourier transform infra-red spectroscope (FTIR) and x-ray photoelectron spectroscopy (XPS) analysis have been carried out to validate the dosages of nano-Al2O3, CA and CAP on PPSU membranes. The membrane's surface charge measurement of 1.5 wt% of nano-Al2O3 in CA/PPSU (ALCA-1.5) was scrutinized by zeta potential analysis. Membranes removed more arsenate oxide as the removal rate from membranes ALCA-1.5 and 1.0 wt% of nano-Al2O3 in CA/PPSU (ALCA-1) was 98.67% and 94.89% with retention permeabilities of 88.41 L/m2h bar and 53.53 L/m2h bar respectively from laboratory prepared 1 ppm of aqueous arsenic solution with pH in the range 6.8 ± 0.2 at 1 bar transmembrane pressure. In addition, membrane's antifouling analysis was performed using laboratory prepared 0.8 g/L (Bovine Serum Albumin) BSA as standard protein solution.

Preparation and Characterization of Reduced Graphene Oxide /TiO2 Blended Polyphenylene sulfone Antifouling Composite Membrane With Improved Photocatalytic Degradation Performance.

Nanosized titanium oxide (TiO2)-based photocatalysts have exhibited great potential for the degradation of organic contaminants, while their weak absorption of visible light limits the photocatalytic efficiency. Herein, a novel reduced graphene oxide/TiO2-polyphenylenesulfone (rGO/TiO2-PPSU) hybrid ultrafiltration membrane has been successfully prepared via a non-solvent induced phase-separation method, in which the synergistic coupling between the rGO and TiO2 could endowed the fabricated membranes with visible-light-driven efficient photocatalytically degradation of organic pollutants and outstanding photocatalytic and antifouling properties. Compared with the PPSU membranes prepared with Graphene oxide and TiO2, respectively, the rGO/TiO2-PPSU membrane demonstrated significant photodegradation towards phenazopyridine hydrochloride (PhP) solution under ultraviolet light (improved about 71 and 43%) and visible light (improved about 153 and 103%). The permeability and flux recovery rates of the membrane indicated that the high flux of the rGO/TiO2-PPSU membrane can be greatly restored after fouling, due to the improved self-cleaning properties under visible light static irradiation. With the properties of high performance of photocatalytic degradation and good self-cleaning ability, the rGO/TiO2-PPSU membrane would have great potential in water treatment.

Preparation of polyphenylsulfone/graphene nanocomposite membrane for the pervaporation separation of cumene from water

AbstractPolyphenylsulfone (PPSU) was applied for the first time in the hydrophobic PV process. Nanocomposite membranes of PPSU/graphene (Gr) nanosheets were prepared and used to separate isopropyl benzene (cumene) from water via pervaporation (PV). Analysis of the mechanical properties of the membranes showed that the tensile strength and Young's modulus had an increasing trend with the incorporation of Gr into PPSU. The water contact angle of the membranes had a rising trend with the addition of Gr, confirming the improved hydrophobicity of membranes. In the PV experiments, the membrane containing 3.5 wt% Gr provided the highest separation factor, which was 4.5‐fold as much as that of the neat PPSU membrane. Cumene separation from water by the PPSU/3.5 wt% Gr membrane was associated with the total flux of 132.73 gMH, the separation factor of 1566.36, and the PSI of 208,124.8 gMH.

Fabrication of Gum Arabic-Graphene (GGA) Modified Polyphenylsulfone (PPSU) Mixed Matrix Membranes: A Systematic Evaluation Study for Ultrafiltration (UF) Applications.

In the current work, a Gum, Arabic-modified Graphene (GGA), has been synthesized via a facile green method and employed for the first time as an additive for enhancement of the PPSU ultrafiltration membrane properties. A series of PPSU membranes containing very low (0–0.25) wt.% GGA were prepared, and their chemical structure and morphology were comprehensively investigated through atomic force microscopy (AFM), Fourier transforms infrared spectroscopy (FTIR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). Besides, thermogravimetric analysis (TGA) was harnessed to measure thermal characteristics, while surface hydrophilicity was determined by the contact angle. The PPSU-GGA membrane performance was assessed through volumetric flux, solute flux, and retention of sodium alginate solution as an organic polysaccharide model. Results demonstrated that GGA structure had been successfully synthesized as confirmed XRD patterns. Besides, all membranes prepared using low GGA content could impart enhanced hydrophilic nature and permeation characteristics compared to pristine PPSU membranes. Moreover, greater thermal stability, surface roughness, and a noticeable decline in the mean pore size of the membrane were obtained.

Effects of coagulation-bath conditions on polyphenylsulfone ultrafiltration membranes

Polyphenylsulfone (PPSU) ultrafiltration membrane with different structures was prepared by non-solvent-induced phase separation. The effects of coagulation bath conditions (concentration and temperature) on membrane morphology, pure water flux, pore size, porosity, and contact angle were studied and discussed based on ternary-phase diagrams. Results indicated that water had stronger coagulant power than ethanol, and that the morphology of the membrane prepared from the polyphenylsulfone/1-methyl-2-pyrrolidinone/H2O (PPSU/NMP/H2O) system had finger-like structures. Conversely, sponge-like structures were observed for the PPSU/NMP/(NMP-H2O) and PPSU/NMP/(70NMP-EtOH-H2O) systems. Ethanol also greatly influenced on membrane structures. According to the Scanning electronic microscopy (SEM) image, the composition (mass fraction) of casting solution is 16% PPSU-84% NMP and the coagulation bath consisting of 70% NMP-26% H2O-4% C2H5OH. Meanwhile, the PPSU ultrafiltration membrane with spong-like was prepared under 8 ℃ coagulation bath. The formation of sponge-like structure reduces the pure water flux of ppsu membrane from 488.39 L·m−2·h−1 to 36.04 L·m−2·h−1. It also reduces the gas permeability, porosity, and pore size of the membrane. The addition of ethanol and NMP into the coagulation bath increases the roughness of the PPSU ultrafiltration membrane and reduces the hydrophilicity of the membrane.

Removal of Antibiotics and Histological Dyes from Simulated Bio-Industrial Wastewater with a Dual Pore Size PPSU Membrane

Removal of Antibiotics and Histological Dyes from Simulated Bio-Industrial Wastewater with a Dual Pore Size PPSU Membrane

Polyphenylsulfone/multiwalled carbon nanotubes mixed ultrafiltration membranes: Fabrication, characterization and removal of heavy metals Pb2+, Hg2+, and Cd2+ from aqueous solutions

Polyphenylsulfone/multiwalled carbon nanotubes/polyvinylpyrrolidone/1-methyl-2-pyrrolidone mixed matrix ultrafiltration flat-sheet membranes were fabricated via phase inversion process to inspect the heavy metals separation efficacy from aqueous media. Fabricated membranes cross-sectional morphological changes and the topographical alterations were assessed with Scanning electron microscopy (SEM) and atomic force microscopy (AFM). Particularly, MWCNTs assisted membranes exhibited better permeability ability as well as heavy metal removal enactment than virgin membrane. The dead-end filter unit was engaged in current research to examine the permeability and heavy metal removal competence of membranes. With the continuous enhancement of MWCNTs wt% in a polymer matrix, significant enhancement was observed with pure water flux study, from 41.69 L/m2 h to >185 L/m2 h as well as with the heavy metals separation study. Added additive MWCNTs can impact the pore sizes in membranes. The heavy metal separation results achieved, the membrane with 0.3 wt% of MWCNTs (PCNT-3) exhibited >98%, >76% and >72% for Pb2+, Hg2+ and Cd2+ ions, respectively. Overall, MWCNTs introduced PPSU membranes exposed best outcomes with heavy metals contained wastewater treatment.

Fabrication and characterization of a defect-free mixed matrix membrane by facile mixing PPSU with ZIF-8 core–shell microspheres for solvent-resistant nanofiltration

Metal–organic frameworks (MOFs) nanoparticles can act as microporous fillers to fabricate high-performance mixed matrix membranes (MMMs) for solvent-resistant nanofiltration (SRNF) application. However, a high content of MOFs nanoparticles mixed in a polymeric membrane may be easily to form MOFs aggregates and MOFs/polymer interface defects, attributing to the decrease in membrane selectivity. In this study, ZIF-8 core–shell microspheres were synthesized by growing microporous ZIF-8 nanoparticles on the outer surface of macroporous resin microspheres (RMs), and then polyphenylsulfone (PPSU)/ZIF-8@RMs membranes were prepared in order to avoid the nonselective PPSU/ZIF-8 defects and then to improve SRNF performance of PPSU membranes. The effects of different type of fillers and ZIF-8@RMs content in PPSU MMMs were evaluated with respect to structural properties and SRNF performance. The obtained PPSU/ZIF-8@RMs membranes exhibited higher selectivity compared with the PPSU/ZIF-8 and PPSU/RMs membranes, due to the combination of the affinity of ZIF-8 nanoparticles, the microporous and microsphere structure of the ZIF-8 shells is benefit to reduce the defects between ZIF-8@RMs and PPSU. Compared with the pure PPSU membrane (with a rejection of 53% and a methanol flux of 35.2 kg m−2 h−1) for Methyl red (MR) removal, the optimal PPSU/ZIF-8@RMs membrane with filler content of 5.0 wt% significantly exhibited the improved rejection of 88.8% and the methanol flux slightly decreased to 33.0 kg m−2 h−1 at 1.0 MPa. Moreover, the PPSU/5.0 wt% ZIF-8@RMs membrane remained stable in 12-h SRNF process, and the MR rejection exceeding 86.2% was maintained. This method provides a good prospect for the combination of polymeric membranes and more types of MOF core–shell composite materials.

Silver nano-particle coated hydroxyapatite nano-composite membrane for the treatment of palm oil mill effluent

Nano-composite ultra-filtration membranes were developed for the treatment of Palm Oil Mill Effluent (POME). Silver nano-particle was synthesized and was used to coat hydroxyapatite nanotubes. This coated nano-filler was used as filler for the polyphenylsulfone (PPSU) membrane. The filler composition in the membrane was varied from 0 to 2.5 wt% to investigate the effect of fillers on the separation properties of the membrane. Both dead-end and cross-flow techniques were used for the separation. Characterization techniques such as contact angle analysis, particle size analyzer, XRD, SEM were used to analyze both nanoparticles as well as the nano-composite membranes. Parameters like COD, BOD, turbidity, suspended solids, pH, conductivity and TDS of the permeate were studied. Change in intrinsic membrane resistance with respect to filler composition was also studied. Based on the results the membrane having a filler composition of 2% was found to be exhibiting excellent properties compared to other membranes in terms of separation performances. The rejection percentage of PPSU membrane with a filler content of 2% was 89.74%. The composite membrane had shown promising results by removing all the organic matter present in the POME and can be further developed into a pilot plant.

Selective ion removal and antibacterial activity of silver-doped multi-walled carbon nanotube / polyphenylsulfone nanocomposite membranes

This study focuses on selective ion removal and antibacterial applications of silver-doped multiwalled carbon nanotube (MWCNT)/polyphenylsulfone (PPSU) nanocomposite membranes. The prepared Ag-doped MWCNTs are characterized according to their particle size distribution and specific surface area. Further, they are examined using transmission electron microscopy and several spectroscopic techniques; their morphology, topography, surface charge, porosity, and contact angles are reported. A performance evaluation demonstrates that the Ag-MWCNT/PPSU nanocomposite membrane exhibits unique properties and achieves optimal performance. The nanocomposite membrane exhibits significantly improved selective removal of Na2HAsO4, Na2Cr2O7, Na2SO4, NaCl, MgSO4, and MgCl2 ions from aqueous solutions compared to the pristine PPSU membrane. The antibacterial activity is evaluated using Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria, and is found to be enhanced by the presence of Ag-MWCNTs, which endow the nanocomposite membrane with excellent antibacterial activity. Hence, the developed Ag-MWCNT/PPSU nanocomposite membrane with improved ion removal performance and antibacterial activity could be suitable for use in potable water applications.