Polysulfone Research Articles

Fabrication of a family of porous azo polymers with multifunctional adsorption and separation performances

In this paper, a class of porous organic polymers (POPs) of p-hydroxy azobenzene with a mesoporous structure was designed and synthesized by a –NN– coupling reaction of tetraamino-metal phthalocyanine (MTAPc, where M = Co, Ni or Cu) with hydroquinone (namely Azo-MHQ, where M = Co, Ni or Cu). The Azo-MHQ materials possessed good thermal stabilities, excellent dispersibilities in water, polar and non-polar organic solvents, as well as excellent chemical stabilities. Among them, Azo-CuHQ showed an outstanding iodine trapping ability in an iodine solution and vapor with saturated adsorption capacities of 1347.47 mg g−1 and 118 wt%. In addition, Azo-CuHQ also showed a high adsorption capacity for methylene blue (MB) with the adsorption amount of 191.21 mg g−1. Furthermore, by loading Azo-CuHQ onto polyethersulfone (PES) membrane, the water permeability of the obtained membranes reached 147.03 L m−2 h−1 bar−1, and the retention rate of Ag in a very low concentration solution of 20 ppm was 56.8 %. Additionally, a thorough analysis of the Azo-CuHQ adsorption and separation mechanism was conducted. A novel approach to the design and synthesis of a class of materials with multifunctional adsorption and separation capabilities is presented in this research.

Fluorescent Aromatic Polyether Sulfones: Processable, Scalable, Efficient, and Stable Polymer Emitters and Their Single-Layer Polymer Light-Emitting Diodes.

In this study, fully aromatic polyether sulfones were developed, bearing blue, yellow, and orange-red π-conjugated semiconducting units. Carbazole-, anthracene-, and benzothiadiazole-based fluorophores are copolymerized with a diphenylsulfone moiety. A diphenylpyridine comonomer was additionally utilized, acting as both a solubilizing unit and a weak blue fluorescent group. Using this rationale, fluorescent polyarylethers with high molecular weights, up to 70 kDa, were developed, showing film formation ability and high thermal stability, while preserving excellent solubility in common organic, nonvolatile, and nonchlorinated solvents. Fine-tuning of the emission color was achieved through subtle changes of the comonomers' type and ratio. Single-chromophore-bearing copolymers emitted in the blue or the yellow region of the visible spectrum, while the dual-chromophore-bearing terpolymers emitted throughout the visible spectrum, resulting in white light emission. Solutions of 20 wt% in polar aprotic solvents at ambient conditions allowed the deposition of fluorescent copolyethers and printing from non-chlorinated solvents. All polyethers were evaluated for their structural and optoelectronic properties, and selected copolymers were successfully used in the emitting layer (EML) of organic light-emitting diode (OLED) devices, using either rigid or flexible substrates. Remarkable color stability was displayed in all cases for up to 15 V of bias voltage. The Commission Internationale de L'Eclairage (CIE) of the fabricated devices is located in the blue (0.16, 0.16), yellow (0.44, 0.50), or white region of the visible spectrum (0.33, 0.38) with minimal changes according to the ratio of the comonomers. The versatile methodology toward semiconducting polyethersulfones for polymer light-emitting diodes (PLEDs) developed herein led to the scaled-up production of luminescent polymers of up to 25 g of high-molecular-weight single batches, demonstrating the effectiveness of this approach as a straightforward tool to facilitate the synthesis of flexible and printable EMLs for large-area PLED coverage.

Developing a Passive Dosing Method for Acute Aquatic Toxicity Tests of Cationic Surfactant Benzalkoniums (BACs).

Benzalkonium chlorides (BACs) have been of environmental concern due to their widespread use and potential harm. However, challenges arise in defining and controlling the exposure concentration (Cw) in aquatic toxicity tests involving BACs with a long alkyl chain (i.e., #C > 14). To address this, a novel passive dosing method was introduced in the 48 h-acute ecotoxicity test on Daphnia magna and compared to the conventional solvent-spiking method in terms of Cw stability and toxicity results. Among 13 sorbent materials tested for their sorption capacity, poly(ether sulfone) (PES) membrane was an optimal passive dosing reservoir, with equilibrium desorption of BACs to water achieved within 24 h. The Cw of BACs remained constant in both applied dosing methods during the test period. However, the Cw in solvent-spiking tests was lower than the nominal concentration for long-chain BACs, particularly at low exposure concentrations. Notably, the solvent-spiking tests indicated that the toxicity of BACs increased with alkyl chain length from C6 to 14, followed by a decline in toxicity from C14 to 18. In contrast, the passive dosing method displayed similar or slightly increasing toxicity levels of BACs from C14 to C18, indicating higher toxicity of C16 and C18-BACs than that inferred by the solvent spiking test. These findings emphasize the potential of applying this innovative passive dosing approach in aquatic toxicity tests to generate reliable and accurate toxicity data and support a comprehensive risk assessment of cationic surfactants.

Mixed-matrix membrane designed with water channels and sieving effect for effective removal of heavy metals

The challenge of eliminating heavy metal ions from water has been addressed using Polysulfone (PSf) membranes, which have demonstrated significant potential in treating contaminated solutions. This research aimed to improve the permeability and separation performance of PSf membranes by incorporating Al2SiO6 into their structure. The introduction of Al2SiO6 into the membrane matrix was achieved through the nonsolvent-induced phase separation (NIPS). The resulting mixed-matrix membrane (MMM) exhibited improved efficiency in water filtration. The inclusion of Al2SiO6 led to desirable changes in membrane properties such as hydrophilicity, contact angle and porosity, thereby enhancing the performance of heavy metal ion removal capability. Under a pressure of 2 bar, the mixed matrix membranes achieved rejections exceeding 95 % for lead and 70 % for arsenic. Furthermore, the occurrence of Al2SiO6 enhanced the anti-fouling assets of the PSf membrane by increasing its hydrophilic nature and facilitating the development of a hydration layer, which tends to prevent the interactions between the membrane surface and foulant. These properties make these membranes suitable candidates for separating toxic ions from water.

Enhancement of Co(II) removal via coupling of electrosorption and electrodeposition using asymmetric electrode from wastewater

The growing demand for nuclear energy and the promotion of nuclear technology applications will generate large quantities of cobalt-containing wastewater. The efficient removal of cobalt from radioactive wastewater is of great significance for the resource regeneration and environmental protection. However, conventional removal methods are constrained by the poor removal efficiency and slow removal kinetics. Herein, the sulfonated polyether ether ketone coated activated carbon fibers (anode)/activated carbon fibers (cathode) asymmetric electrodes was proposed to boost the Co(II) electrosorption performance. The experimental results showed that compared to traditional symmetric electrodes, the theoretical maximum electrosorption capacity (116.19 mg·g−1) had an exceptional enhancement of 69 %. The voltage and initial pH of the solution had an undeniable impact on the efficiency of cobalt electrosorption. Furthermore, more than 75 % of Co(II) was rapidly immobilized within 3 h. The kinetic fitting indicated that the electrosorption process was more appropriately described by pseudo-second-order kinetic model. The Co(II) removal efficiency was up to 80 % under the conditions of coexistence with Na+, Mn2+, Ni2+, Zn2+, Sr2+, and Cs+. More importantly, it combines two synthetic mechanisms of electrosorption and electrodeposition to realize the purification of cobalt-containing wastewater. Overall, considering the fast and highly-efficient cobalt removal performance and innate economy, the asymmetric electrosorption for cobalt removal provides new insights into the treatment of cobalt-containing wastewater.

High performance and robust durability proton conductive composite membranes containing CeO2-TiC incorporated sulfonated poly(arylene ether) for hydrogen fuel cells

Degradation of proton exchange membrane (PEM) due to free radicals often decreases the overall performance of proton exchange membrane fuel cells (PEMFC). The incorporation of antioxidative additives into the polymer matrix has been widely exploited to mitigate oxidative degradation but is still challenging. Herein, butylsulfonated poly(arylene ether)(SAFPAE) was synthesized by polycondensation followed by nucleophilic substitution and highly crystalline CeO2-TiC filler was prepared by simple hydrothermal process. SAFPAE alleviates the problematic characteristics of proton-exchange membranes (PEMs) whereas CeO2 scavenges free radicals and TiC improves tensile strength. Variable weight ratios of CeO2-TiC were blended into the SAFPAE matrix to study its physicochemical, and electrochemical properties. The random distribution of CeO2-TiC in the SAFPAE matrix enhanced thermal and mechanical strength and increased water absorption, ion exchange capacity, as well as proton conductivity. Specifically, SAFPAE/CeO2-TiC (1.0 wt%) exhibited a current output of 0.18 A cm−2 and a power output of 0.087 Wcm−2 at 20 % RH and 60°C. It also experienced a degradation of 0.145 mV h−1 over 1100 hours of operation. Under operating conditions of RH 20 % and 60°C, PEMFCs with SAFPAE/CeO2-TiC (1.0 wt%) membrane exhibited significantly improved performance and enhanced durability compared to PEMFCs with pure SAFPAE and without sacrificing their cell performance.

Investigating the effect of ZIF-8@PEI filler and its comparison with ZIF-8 in mixed matrix membranes for CO2/CH4 separation with the help of DFT study

In this study, Zeolitic Imidazolate Framework-8 (ZIF-8) and modified ZIF-8 (ZIF-8@PEI)with polyethyleneimine (PEI) were used as dispersed particles inside the polysulfone (PSF) matrix to separate CO2 and CH4. The distributions of dispersed particles in mixed matrix membranes (MMMs) were analysed with the help of Fourier transfer infrared radiation, Thermal gravimetric analysis, Scanning electronic microscope and X-ray diffraction. The mixed matrix membranes investigated the permeability and selectivity of pure gas (CO2) and mixed gas (CO2/CH4). It was highest at 5 wt% ZIF-8@PEI blended into the PSF matrix. In case of pure gas studies, we investigated the CO2 permeability (18.10 Barrer) and CO2/CH4 selectivity (23.91) as compared to ZIF-8/PSF MMM (10.36 Barrer, 5.81); and in case of mixed gas studies, the CO2 permeability (17.11 Barrer) and CO2/CH4selectivity (21.28) as compared to ZIF-8/PSF MMM (7.86 Barrer, 4.21).Using DFT studies, the interaction energies of the ZIF-8@PEI material with CO2 and CH4 gas molecules werefound to be -74.39 kJ/mol and -23.25 kJ/mol, respectively. It was more toward the ZIF-8@PEI-CO2geometry complex.From the observation, the experimentalgas permeation results and DFT studiesinvestigated that ZIF-8@PEI filler can be a good candidate for applying CO2 capture.

Incorporation of polydopamine functionalized as double‐sided adhesive to connect phosphotungstic acid in Friedel‐Crafts cross‐linked SPEEK sulfonated poly(ether eether ketone) as proton exchange membranes

AbstractUsing highly sulfonated poly(ether ether ketone) (SPEEK) as the base material, the structure and properties of poly(ether ether ketone) (PEEK) membranes are optimized by precisely controlling the doping of phosphotungstic acid (HPW), dopamine (DA), and various amounts of carbon nanomaterials. Compared with conventional PEEK membranes, this optimized membrane exhibits higher proton conductivity, lower water absorption swelling rate, and excellent thermal stability. Highly SPEEK is soluble in water, thus fails to be used in fuel cell applications. Herein, we conduct Friedel‐Crafts method to obtain cross‐linked highly sulfonated membrane with controlled water uptake and swelling while still maintaining high proton conductivity. The polymer is then doped with phosphotungstic acid (HPW) to acquire enhanced performance. To control HPW leakage, polydopamine (PDA) acting as double‐sided adhesive is incorporated within the membrane. By distributing 1 wt.% PDA, the HPW leakage is reduced almost three times. The composite C‐SPEEK/HPWx/PDAy membranes have exhibited excellent overall performance. Specifically, the best proton conductivity result of C‐SPEEK/HPW50 has reached 0.271 S/cm. Moreover, it has presented superb performance in H2/O2 single cell test recorded as power density of 886.13 mW/cm2 while current density is 1614.20 mA/cm2 at 60°C.

Application of Modified Polyether Sulfone Microspheres in Hyperbilirubinemia

To design and prepare a high efficiency bilirubin adsorbent with good mechanical properties and biocompatibility. In this study, quaternary ammonium pyridine was designed and synthesized, and then modified polyether sulfone microspheres, or PES/p(4-VP-co-N-VP)@6 microspheres, were prepared by phase conversion and electrostatic spraying. The morphology of the polymer components and the microspheres were studied by means of nuclear magnetic resonance (NMR) spectroscopy and scanning electron microscopy. The basic properties of the microspheres and their bilirubin adsorption efficiency were tested, and the adsorption mechanism was further explored. Blood cell counts and the clotting time of the microspheres were also measured. The diameter of the modified polyether sulfone microspheres prepared in the study was approximately 700-800 μm. Compared with the original PES microspheres, the surface and internal structure of PES/p(4-VP-co-N-VP)@6 microspheres did not change significantly, and they also had a loose porous structure, with some micropores scattered around in addition to irregular large pores. Compared with the control group, the bilirubin removal effect of the modified microspheres was (94.91±0.73)% after static adsorption in bilirubin PBS buffer solution for 180 min, with the difference being statistically significant (P<0.0001). According to the findings for the clotting time, the activated partial thromboplastin time (APTT) of the blank plasma group, the control PES group, and the modified PES microsphere group were (27.57±1.25) s, (28.47±0.45) s, and (30.4±0.872) s, respectively, and the difference between the experimental group and the other two groups was statistically significant (P<0.01, P<0.05). There was no significant change in red blood cell and white blood cell counts. The microspheres prepared in the study have high efficiency in bilirubin adsorption, excellent mechanical properties and thermal stability, and good blood biocompatibility, and are expected to be used in the clinical treatment of patients with liver failure.

Cleaning of Ultrafiltration Membranes: Long-Term Treatment of Car Wash Wastewater as a Case Study.

Car wash wastewaters (CWWs) contain various pollutants with different contents. Hence, selecting an appropriate process for their treatment is a great challenge. Undoubtedly, the ultrafiltration (UF) process is one of the most interesting and reliable choices. Therefore, the main aim of the current study was to investigate the performance of the UF membranes used for the long-term treatment of real CWWs. For this purpose, two polyethersulfone (PES) membranes with molecular weight cut-off (MWCO) values equal to 10 and 100 kDa were applied. As expected, a significant decrease in the permeate flux during the UF run was observed. However, it was immediately demonstrated that the systematic cleaning of membranes (every day) with Insect agent (pH = 11.5) prevented a further decline in the process's performance. In addition, this study focused on the relative flux during the process run with breaks lasting a few days when the UF installation was filled with distilled water. The results of this research indicated that aqueous media favor microorganism adherence to the surface which leads to the formation of biofilms inside processing installations. As a consequence, many attempts have been made to restore the initial membrane performance. It has been found that the application of several chemical agents is required. More precisely, the use of an Insect solution, P3 Ultrasil 11 agent, and phosphoric acid increases the relative flux to a value of 0.8. Finally, it has been indicated that the membranes used in this work are resistant to the long-term exposure to bacteria and chemical agents. However, during the separation of CWWs for the membrane with an MWCO of 10 kDa, a lesser fouling influence and higher effectiveness of cleaning were obtained. Finally, the present study demonstrates a novel analysis and innovative implications towards applying the UF process for the CWW treatment.

Graphene oxide decorated copper nanoparticles embedded polysulfone nanocomposite membrane: Anti-bacterial, organo-bio fouling evaluation in pharmaceutical wastewater treatment via MBR

This study investigates the impact of incorporating graphene oxide (GO) nanosheets and copper nanoparticles decorated reduced graphene oxide (Cu/rGO) on the performance of polysulfone (PSf) membranes in a membrane bioreactor (MBR) system. The characterization of the synthesized nanomaterials confirmed superior antibacterial activity of Cu/rGO compared to GO. Compared to the neat PSf membrane, the prepared nanocomposite membranes exhibited enhanced antibacterial, hydrophilic properties, pure water flux and porosity. Furthermore, the morphological analysis suggested that the GO and Cu/rGO nanohybrids exhibited outstanding interface compatibility and less release (<7%) during 20 days of immersion. During the treatment of the pharmaceutical wastewater in bench scale MBR system, total fouling ratio (TFR) was decreased from 80.24 % for neat PSf membrane to 74.37 % and 67.85 % for PSf-GO and PSf-Cu/rGO membranes, respectively. Notably, the flux recovery ratio (FRR) of the optimized PSf-Cu/rGO and PSf-GO nanocomposite membranes significantly increased 1.44 and 1.25 folds compared to the neat PSf membrane, respectively. The analysis of extracellular polymeric substances indicated an outstanding reduction in protein and carbohydrate concentrations in the cake layer in the presence of nanohybrids, confirming the membranes’ ability to mitigate organic and bio-fouling. These findings suggest GO and Cu/rGO nanohybrids enhance PSf membranes performance in MBR applications.

PSF@PAO40 microcapsules enhanced epoxy resin coating toward anti-wear/corrosion performance

Microcapsules-enhanced coating emerges as the times require since the traditional organic coating hardly realizes the long-term protection of metal materials. Herein, PSF@PAO40 microcapsules (PPs) were prepared via Poly α-olefin 40 (PAO40) encapsulated within Polysulfone (PSF) shell using solvent evaporation method. Then self-lubricating composite coatings were fabricated by introducing PPs into epoxy resin (EP). The coating structure was characterized using X-ray microtomography (CT), and its relationship with anti-wear/corrosion performance was explored. Compared to pure EP coating, the composite coatings with 10 wt% PPs demonstrated an 87.9 % reduction in friction coefficient and 84.5 % reduction in wear rate. Additionally, the lowest frequency impedance (|Z|0.01 Hz) increased by 1 order of magnitude. Superior anti-wear/corrosion performance of the composite coatings is primarily attributed to the three-dimensional network distribution structure of PPs, which facilitate continuous lubrication and provide a physical barrier against corrosive media.

Simultaneous enhanced antibiotic pollutants removal and sustained permeability of the membrane involving CoFe2O4/MoS2 catalyst initiated with simple H2O2 backwashing

Membranes for wastewater treatment should ideally exhibit sustainable high permeate production, enhanced pollutant removal, and intrinsic physical rejection. In this study, CoFe2O4/MoS2 serves as a non-homogeneous phase catalyst; it is combined with polyether sulfone membranes via liquid-induced phase separation to simultaneously sustain membrane permeability and enhance antibiotic pollutant degradation. The prepared catalytic membranes have higher pure water flux (329.34 L m−2 h−1) than pristine polyethersulfone membranes (219.03 L m−2 h−1), as well as higher mean pore size, porosity, and hydrophilicity. Under a moderate transmembrane pressure (0.05 MPa), tetracycline (TC) in synthetic and real wastewater was degraded by the optimal catalytic membrane by 72.7 % and 91.2 %, respectively. Owing to the generation of the reactive oxygen species (ROS) during the Fenton-like reaction process, the catalytic membrane could exclude the natural organics during the H2O2 backwash step and selectively promote fouling degradation in the membrane channel. The irreversible fouling ratio of the catalyzed membrane was significantly reduced, and the flux recovery rate increased by up to 91.6 %. A potential catalytic mechanism and TC degradation pathways were proposed. This study offers valuable insights for designing catalytic membranes with enhanced filtration performance.

Mechanical Enhancement and Water Treatment Efficiency of Nanocomposite PES Membranes: A Study on Akçay Dam Water Filtration Application.

Polymeric membranes are widely used in water treatment because of their ease of fabrication and low cost. The flux and purification performance of membranes can be significantly improved by incorporating appropriate amounts of nanomaterials into the polymeric membrane matrices. In this study, neat poly(ether sulfone) (PES), PES/nano copper oxide (CuO), and PES/nano zinc oxide (ZnO) membranes are fabricated via phase inversion. The pure water flux of the neat PES membrane, which is 355.14 L/m2·h, is increased significantly with the addition of nano-CuO and nano-ZnO, and the pure water fluxes of the nanocomposite membranes vary in the range of 392.65-429.74 L/m2·h. Moreover, nano CuO and nano ZnO-doped PES nanocomposite membranes exhibit higher conductivity, color, total organic carbon, boron, iron, selenium, barium, and total chromium removal efficiencies than neat PES membranes. The membrane surfaces examined by Scanning Electron Microscopy (SEM) after water filtration revealed that those containing 0.5% wt. nano CuO and nano ZnO are more resistant to fouling than the membrane surfaces containing 1% wt. nano CuO and nano ZnO. Based on the results of this study, 0.5% wt. nano ZnO-doped PES membrane is found to be the most suitable membrane for use in water treatment due to its high pure water flux (427.14 L/m2·h), high pollutant removal efficiency, and high fouling resistance. When the mechanical properties of the membranes are examined, the addition of CuO and ZnO nanoparticles increases the membrane stiffness and modulus of elasticity. The addition of 0.5% and 1% for CuO leads to an increase in the modulus of elasticity by 57.95% and 324.43%, respectively, while the addition of 0.5% and 1% for ZnO leads to an increase in the modulus of elasticity by 480.68% and 1802.43%, respectively. At the same time, the tensile strength of the membranes also increases with the addition of nanomaterials.

The effect of activated carbon nanoparticles (ACNPs) on characterization and mechanical properties of polyethersulfone (PES) ultrafiltration membranes

The effect of activated carbon nanoparticles (ACNPs) on characterization and mechanical properties of polyethersulfone (PES) ultrafiltration membranes

Preparation of thin-film nanocomposite membrane with the addition of cysteine-modified MoS2 to enhance nanofiltration performance

Novel thin-film nanocomposite nanofiltration ((TFN)-NF) membrane was successfully fabricated by adding MoS2 functionalized with cysteine in a polysulfone (PSf) layer and the active layer to enhance separation performance in water and alcohol. A novel TFN-NF membrane was prepared through interfacial polymerization (IP), which reacts with an aqueous DETA solution containing MoS2-cys and a TMC organic solution onto the PSF/MoS2-cys support layer. A PSf support layer was incorporated with MoS2-cys, which enhanced the membrane permeability due to increasing porosity and hydrophilicity. Furthermore, MoS2 is essential in forming thin films and Turing structures of the NF membrane, resulting in enhanced permeability for water and alcohol. The prepared TFN-NF membrane has shown a notable permeability of 7.9 LMH/bar and a rejection rate of 99% for MgSO4. It also demonstrated excellent fouling resistance after three chemical cleaning cycles and long-term running. The TFN-NF membrane with MoS2 showed improved permeability for water and alcohol solvents, such as methanol and ethanol, of 5.5, 1.2, and 0.48 LMH/bar, respectively. This work would present a valuable strategy for preparing a TFN-NF membrane to retrieve alcohol solvents.

A new nanocomposite membrane based on sulfonated polysulfone boron nitride for proton exchange membrane fuel cells: Its fabrication and characterization

Sulfonated polysulfone (SPSf) polymer is an alternative raw material in producing commercially used proton exchange membranes. On the other hand, hexagonal boron nitride (hBN) is one of the additives of interest for nanocomposite PEMs. In this study, nanocomposite membranes is fabricated and characterized with SPSf and hBN nanoparticles. The degree of sulfonation of the sulfonated polysulfone is determined by titration, and sulfonic acid bonds are investigated by Proton Nuclear Magnetic Resonance (1H NMR) analysis. SPSf is dissolved with dichloromethane, and hBN nanoparticles are added. After homogenizing the prepared solution with magnetic and ultrasonic stirrers, membranes are formed using Dr. Blade. 1H NMR, Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), X-Ray Diffractometer (XRD), and Thermogravimetric Analysis (TGA) analysis are examined the morphological, thermal, and organic compound structures of the membranes. Water uptake capacity, swelling ratio, proton conductivity, oxidative resistance, and mechanical properties of the membranes are determined. The highest water uptake capacity is obtained as 40.08 % in the membrane named SPSf-3 %hBN. Using hBN additive improved swelling ratio and thermal and mechanical strength properties. The proton conductivity values of polysulfone (PSf), SPSf, SPSf-1 %hBN, SPSf-2 %hBN, and SPSf-3 %hBN membranes are determined as 2.89, 6.84, 3.57, 10.8 and 5.12 mS cm−1, respectively. As a result of the analysis, it is observed that the nanocomposite membrane structure has both amorphous and crystalline homogeneous structure.

High permeability Performance TFC Nanofiltration Membrane with Two dimensional Nanochannels Support Layer Fabricated by Dissolving of Nanosheets

A synthesized thin film composite (TFC) nanofiltration membrane was prepared by incorporating Mg(OH)2 nanosheets at different ratios (from 0 to 0.5 wt%) into polysulfone (PSf) support layer. The polypiperazinamide (PPA) layer was prepared on the polysulfone support layer by means of interfacial polymerization. Then TFC membrane was then etched with H2SO4 and a PPA selective layer was established using trimesoyl chloride (TMC) and piperazine (PIP). The characterization results show that the modifications of the PSf substrate with Mg(OH)2 alter the physicochemical properties of the poly(piperazine amide) selective layer. Through the introduction of Mg(OH)2, the hydrophilicity of the TFC membrane was increased (WCA: 20.5°), promoting more linear polypiperinamide. The addition of 0.4 wt% Mg(OH)₂ to the PSf substrate, followed by sulfuric acid etching, resulted in a 196 % increase in membrane flux and with Na₂SO₄ retention at 97.72 %. The change in matrix composition favoured the generation of a lighter and rougher selective layer. The two-dimensional nanochannels in the support layer provided additional channels for water molecule transport. The membrane with two-dimensional nanochannels exhibited excellent resistance to contamination, with a flux recovery of 92.8 % for bovine serum albumin (BSA).

PH controllably induced PPTA/PEMs composite nanofiltration membranes for long-term acid-resistant separation

In this study, we deposited polyelectrolyte multilayers (PEMs) on Poly (p-phenylene terephthamide) (PPTA) ultrafiltration (UF) substrates with strong polyelectrolytes (PEs): polystyrene sulfonic acid (PSS) and poly (diallyldimethylammonium chloride) (PDADMAC). The growth pattern of PEMs was shifted from linear to exponential by changing substrate potential, which was attributed to synergism and antagonism of dispersion of PEs on hydrophilic substrates and electrostatic interaction between PEs and substrates. Eventually, PEMs of layer-dominated and pore-dominated regimes were successfully obtained. We focused on the transition from the pore-dominated to the layer-dominated regime of PEMs. The PEMs nanofiltration (NF) membranes in this situation showed a better separation performance due to the together work of the interface and in-pore energy barriers. The retention rate of Na2SO4 and MgSO4 was 98 % and 91 %. The eosin Y retention rate was 99.9 % and only declined 2 % after 100 h. The hindered deposition of pore-dominated regimes led to denser and thinner layers, which achieved long-term acid resistance. It maintained a stable salt retention after 185 h cross-filtration of 0.1 M H2SO4 feed solution. The performance of PEMs NF membrane was improved from a new perspective, and excellent acid-resistant nanofiltration membranes were obtained, which are expected to be used to treat industrial acidic wastewater.

Novel membrane bioreactor with iron-tannin-framework based membrane for effluent quality improvement and fouling control

A 10 L membrane bioreactor (MBR) was constructed with novel iron-tannin-framework ultrafiltration membrane (ITUM) for membrane fouling mitigation and effluent quality improvement. Compared to commercial ultrafiltration membrane (CUM) in the same MBR, ITUM exhibited hydrophilicity with a contact angle of 64.18° (71.36° for CUM), resulting the permeance of ITUM (50.2 L m-2h−2 bar−1) 1.8 times higher than CUM. During 70-day operation, ITUM was consistently run at lower transmembrane pressure. After operation, the polyethersulfone (PES) peak intensity of ITUM reduced less than 1 % (85 % for CUM), which indicated a thinner sludge layer on ITUM. Meanwhile, the average effluent chemical oxygen demand concentration for ITUM and CUM achieved 16.69 and 17.60 mg L-1 in stable phase, respectively. For NH4+-N, it could reach 0 and 0.04 mg L-1. 16 s RNA results showed that Saccharibacteria accounted for 1.48 % and 1.20 % on ITUM and CUM, respectively. According to first-principles density functional theory simulations, simulated adsorption energies was −1.330 eV for gram-positive bacteria (such as Saccharibacteria). It was −0.867 eV for Fe(Ⅲ) to gram-negative bacteria. It suggests that ITUM could easily attract microorganisms with the ability of polysaccharide degradation, while reducing this type of pollutants deposition on membrane. Therefore, the ITUM received a more superior effluent quality and membrane fouling resistance.