Membrane Material Research Articles

Interfacial Interaction between Functionalization of Polysulfone Membrane Materials and Protein Adsorption.

This study that modified polysulfone membranes with different end-group chemical functionalities were prepared using chemical synthesis methods and experimentally characterized. The molecular dynamics (MD) method were used to discuss the adsorption mechanism of proteins on functionalized modified polysulfone membrane materials from a molecular perspective, revealing the interactions between different functionalized membrane surfaces and protein adsorption. Theoretical analysis combined with basic experiments and MD simulations were used to explore the orientation and spatial conformational changes of protein adsorption at the molecular level. The results show that BSA exhibits different variability and adsorption characteristics on membranes with different functional group modifications. On hydrophobic membrane surfaces, BSA shows the least stable configuration stability, making it prone to nonspecific structural changes. In addition, surface charge effects lead to electrostatic repulsion for BSA and reduce the protein adsorption sites. These MD simulation results are consistent with experimental findings, providing new design ideas and support for modifying blood-compatible membrane materials.

Solvent-resistant isoporous membranes with tailored pore characteristics and on-demand sieving by site-selective hyper-crosslinking

Isoporous block copolymer membranes with high porosity and narrow pore size distribution have been viewed as ideal membrane platforms for precise separation of similarly sized particles or solutes. However, tailored made fabrication of solvent-resistant isoporous membranes with switchable pores and rigid pores for customizable sieving have been rarely reported. Herein, we show that site-selective hyper-crosslinking is effective and robust to prepare such membranes from polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP). The selective crosslinking in PS domains endows the membrane with excellent solvent resistance and structural stability. Since not participated in the crosslinking reaction, the P4VP brushes located in pore walls endow the crosslinked membranes with adaptive pore size, switchable permeance and tunable rejections that vary with Hansen solubility parameter of solvents. Moreover, by a facile while complete etching the P4VP from pores, the switchable performance is removed and resultant membranes show rigid pore characteristics and constant rejections. Crosslinked membranes with either switchable pores or rigid-likes pores exhibit superior long-term stability (30 days) in harsh solvents. This work presents a top-down method to construct highly stable isoporous membranes with both switchable and rigid pore characteristics from the same block copolymer, which will shed the light on precisely tailoring the pore size and pore rigidity for crosslinked isoporous membranes that will not only enable the tailored sieving but also the modelling of solvent flowing behaviours in nanopores.

Pilot-scale performance of gravity-driven ultra-high flux fabric membrane systems for removing small-sized microplastics in wastewater treatment plant effluents

The ubiquitous nature and environmental impacts of microplastic particles and fibers demand effective solutions to remove such micropollutants from sizable point sources, including wastewater treatment plants and road runoff facilities. While advanced methods, e.g., microfiltration and ultrafiltration, have shown high removal efficiencies of small-sized microplastics (<150 μm), the low flux encountered in these systems implies high operation costs and makes them less effective in high-capacity wastewater facilities. The issue presents new opportunities for developing cheap high-flux membrane systems, deployable in low-to high-income economies, to remove small-sized microplastic and nanoplastics in wastewater. Here, we report on developing an ultra-high flux gravity-driven fabric membrane system, assessed through a laboratory-scale filtration and large-scale performance in an actual wastewater treatment plant (WWTP). The method followed a carefully designed water sampling, pre-treatment protocol, and analytical measurements involving Fourier transform infrared (FTIR) spectroscopy and laser direct infrared (LDIR) imaging. The result shows that the ultra-high flux (permeance = 550,000 L/m2h⋅bar) fabric membrane system can effectively remove small-sized microplastics (10–300 μm) in the secondary effluent of an actual WWTP at high efficiency greater than 96 %. The pilot system demonstrated a continuous treatment capacity of 300,000 L/day through a 1 m2 surface area disc, with steady removal rates of microplastics. These findings demonstrate the practical, cheap, and sustainable removal of small-sized microplastics in wastewater treatment plants, and their potential value for other large-scale point sources, e.g., stormwater treatment facilities.

Fabrication of PVDF membranes via γ-ray irradiation and investigation into their membrane formation mechanisms and water treatment properties

Polyvinylidene fluoride (PVDF) membrane is a cheap and commonly used separation material, but its inherent hydrophobicity results in significant membrane contamination, which limits its engineering application and further development. The hydrophilic PVDF-g/co-NVP membrane was prepared through low-dose γ-ray irradiation and using N-vinyl-2-pyrrolidinone (NVP) as a modifier in this study. The effects of γ-ray dose and incorporating NVP additive on the microstructure, hydrophilicity, anti-fouling capability, and mechanical capacity of membranes were discussed. Molecular dynamics (MD) simulation method was used to comprehensively investigate the impact of the NVP on the physicochemical characteristics of membrane structure. Under a specific NVP load, the water contact angle of the membrane decreases from 87.92° to 52.66°. The pure water permeance reaches 362.1 L/m2 h, and the porosity increases to 55.21 %±1.29 %, which indicates that γ-ray irradiation with NVP addition can effectively adjust the pore structure and hydrophilicity of the membrane. During anti-fouling test against bovine serum albumin (BSA), the modified membrane exhibits remarkable anti-fouling characteristics, including reduced BSA accumulation, enhanced flux recovery, lower irreversible contamination level, and extended cleaning cycle compared with the original pure PVDF membrane because of its higher hydrophilicity and positive zeta-potential value. This study elucidates the mechanism underlying γ-ray graft modification of PVDF membranes, thereby providing valuable insights into the development of efficient functional membrane materials.

Covalently modified MoS2 for the fabrication of interlayered thin film composite membranes with excellent structural stability against swelling and drying in organic solvent nanofiltration

Thin film nanocomposite (TFNi) membranes interlayered with 2D nanomaterials are promising for organic solvent nanofiltration (OSN) applications. However, swelling and drying problems can arise due to the instability of the 2D nanomaterial interlayer in different solvents and humidity conditions. To address this issue, covalently modified molybdenum disulfide (MoS2) nanosheets (MoS2–COOH and MoS2–CONH2) were used as interlayers in the fabrication of TFNi membranes. The covalent groups acted as spacers to stabilize the interlayer spacing of the MoS2 interlayer and regulate its structural stability in diverse solvents and drying conditions. The TFNi membranes interlayered with MoS2–COOH and MoS2–CONH2 nanosheets demonstrated excellent structural stability and maintained their high permeance even after exposure to various solvents and drying conditions. The TFNi-MoS2-CONH2 membrane exhibited the highest permeance of 8.60 ± 0.23 L m−2 h−1 bar−1 for MeOH, with a high rejection of 87.1 ± 1.3 % for Evans Blue (EB). Furthermore, the TFNi membranes exhibited sustained separation performance throughout the 72 h test, demonstrating their structural stability. This study highlights the potential of TFNi membranes interlayered with covalently modified MoS2 nanosheets for OSN applications, providing high permeance and structural stability in diverse solvents and drying conditions.

Reaching Quantum Accuracy in Predicting Adsorption Properties for Ethane/Ethene in Zeolitic Imidazolate Framework-8 at Low Pressure Regime.

Nanoporous materials in the form of metal-organic frameworks such as zeolitic imidazolate framework-8 (ZIF-8) are promising membrane materials for the separation of hydrocarbon mixtures. To compute the adsorption isotherms in such adsorbents, grand canonical Monte Carlo simulations have proven to be very useful. The quality of these isotherms depends on the accuracy of adsorbate-adsorbent interactions, which are mostly described using force fields owing to their low computational cost. However, force field predictions of adsorption uptake often show discrepancies from experiments at low pressures, providing the need for methods that are more accurate. Hence, in this work, we propose and validate two novel methodologies for the ZIF-8/ethane and ethene systems; a benchmarking methodology to evaluate the performance of any given force field in describing adsorption in the low-pressure regime and a refinement procedure to rescale the parameters of a force field to better describe the host-guest interactions and provide for simulation isotherms with close agreement to experimental isotherms. Both methodologies were developed based on a reference Henry coefficient, computed with the PBE-MBD functional using the importance sampling technique. The force field rankings predicted by the benchmarking methodology involve the comparison of force field derived Henry coefficients with the reference Henry coefficients and ranking the force fields based on the disparities between these Henry coefficients. The ranking from this methodology matches the rankings made based on uptake disparities by comparing force field derived simulation isotherms to experimental isotherms in the low-pressure regime. The force field rescaling methodology was proven to refine even the worst performing force field in UFF/TraPPE. The uptake disparities of UFF/TraPPE improved from 197% and 194% to 11% and 21% for ethane and ethene, respectively. The proposed methodology is applicable to predict adsorption across nanoporous materials and allows for rescaled force fields to reach quantum accuracy without the need for experimental input.

Incorporating covalent organic framework nanosheets via solvent-exchange strategy boosted hybrid membrane dehydration performance

The uniform dispersion of fillers within the polymer matrix is crucial for the fabrication of hybrid membranes. In this study, we proposed a facile solvent-exchange strategy for developing a hybrid membrane based on a covalent organic framework (COF, TpPa-1), specifically designed to enhance filler distribution in in the membrane towards pervaporation dehydration of butanol/water mixtures. The TpPa-1 nanosheets prepared via a glycerol-mediated method and their hybrid membranes were characterized using SEM, TGA, XPS, BET, FT-IR, and XRD techniques. Molecular dynamics (MD) results revealed that the solvent-exchange strategy significantly enhanced COF nanosheets (CONs) dispersion by removing glycerol. Pervaporation dehydration performance demonstrated significant improvements in total flux and separation factor when TpPa-1 nanosheets and sodium alginate (SA) were integrated, compared to a pure SA membrane. The optimized COF-SA hybrid membrane achieved a total flux of 1753 g/m2·h and a dehydration separation factor of 4687 at 40 °C for 90 wt% butanol/water mixtures. This study not only highlights a viable approach for membrane solvent dehydration but also provides a design strategy for creating hybrid membranes with uniform filler dispersion.

Breaking barriers in passive sampling: The potential of PTFE membranes in the monitoring of hydrophilic micropollutants

Passive samplers are key tools to sample hydrophilic micropollutants in water. Two main approaches address the influence of hydrodynamics: (1) determining site-specific sampling rate (RS) by characterizing kw, the mass transfer coefficient of the water-boundary layer (WBL), and (2) reducing WBL impact using a diffusive material to control the uptake. The first requires calibration data and the second has only been achieved using fragile diffusive material. This study assesses the transfer of hydrophilic contaminants through polytetrafluoroethylene (PTFE; 30 µm thick), a new membrane material with lower sorption than commonly used polyethersulfone (PES). Combined for the first time in a Chemcatcher-like configuration, we calibrated the modified samplers for 44 micropollutants to provide RS – kw relationships for in-situ RS determination (approach 1). Micropollutants accumulated over 2000 times more on the sorbent than on PTFE. PTFE-based RS (0.027 to 0.300 L day-1) were 2.5 higher than previously reported with PES. Membrane property measurements (porosity, tortuosity) indicated that accumulation is primarily controlled by the membrane. Extrapolation indicated that using thicker PTFE membranes (≥ 100 µm) would shift uptake control entirely to the membrane in river conditions (approach 2). This finding could enable RS prediction based on contaminants properties, thus representing a significant advancement in passive sampling.

2-Methylpyrazine: A Greener Solvent for Nonsolvent Induced Phase Separation (NIPS) Membrane Fabrication

2-Methylpyrazine: A Greener Solvent for Nonsolvent Induced Phase Separation (NIPS) Membrane Fabrication

Fabrication of hollow fiber composite membranes via opposite transmission reaction method for dye/salt separation

The separation layer prepared by the conventional coating-crosslinking method is typically thick and prone to forming defective macropores, significantly affecting the water permeability and dye/salt separation performance of membranes. This work presented a novel method to prepare hollow fiber composite membranes for dye/salt separation based on the opposite transmission reaction of crosslinker. In this method, the macromolecule in situ reacted with a small‐molecule crosslinker at the openings of membrane pore channels, forming a separation layer with discontinuous sheet-like and granular structure. Compared to the conventional forward coating-crosslinking method, the separation layer prepared by the opposite transmission reaction method exhibited an ultra-thin thickness of 29.1 nm. Consequently, the composite membrane exhibited a high water permeability of 72.7 L·m−2·h−1·bar−1, which was 2.3 times higher than that of conventional methods. Moreover, the prepared composite membrane presented a more uniformed pore structure, completely retaining the VBB (100%) with a low Na2SO4 rejection of 4.3%, demonstrating excellent dye/salt separation performance. Additionally, the prepared composite membrane exhibited superior anti-fouling properties compared to that prepared by the conventional method. Therefore, the opposite transmission reaction method proposed in this study held promising applications in the preparation of hollow fiber composite membranes for efficient dye/salt separation.

Modeling and Optimization of the Air-Supported Membrane Coal Shed Structure in Ports

The air-supported membrane coal shed is widely used in bulk cargo terminals. It not only effectively protects goods from adverse weather conditions but also helps reduce coal dust and harmful gas emissions, promoting the green and sustainable development of ports. However, in practical engineering, the design parameters of the coal shed are often based on experience, making it difficult to accurately assess the quality of the structural design. The flexibility of the membrane material also makes the structure susceptible to deformation or tearing. This paper mainly focuses on modeling and solving the optimization design issues of air-supported membrane coal shed structures. According to the evaluation criteria for the form of air-supported membrane coal sheds, a multi-objective structural optimization model is established to minimize the maximum stress on the membrane surface, ensure uniform stress distribution, maximize structural stiffness, and minimize costs. The study utilizes a combined optimization approach using ANSYS 19.0 and MATLAB 2016a, incorporating an improved NSGA-II algorithm program developed in MATLAB into ANSYS for structural form analysis and load calculation. The research results indicate that the optimal solution reduces the maximum stress on the loaded membrane surface by 5.36%, shortens the maximum displacement by 30.3%, and saves on economic costs by 9.85%. Compared to traditional empirical design methods, the joint use of MATLAB and ANSYS for optimization design can provide more superior solutions, helping ports to achieve environmental protection and economic efficiency goals.

Double-drying 3D lamellar-structured aerogel membrane for efficient oil-water separation and long-lasting antibacterial activity

Conventional oil-water separation membranes are difficult to establish a trade-off between membrane flux and separation efficiency, and often result in serious secondary contamination due to their fouling issue and non-degradability. Herein, a double drying strategy was introduced through a combination of oven-drying and freeze-drying to create a super-wettable and eco-friendly oil-water separating aerogel membrane (TMAdf). Due to the regular nacre-like structures developed in the drying process and the pores formed by freeze-drying, TMAdf aerogel membrane finally develops regularly arranged porous structures. In addition, the aerogel membrane possesses excellent underwater superoleophobicity with a contact angle above 168° and antifouling properties. TMAdf aerogel membrane can effectively separate different kinds of oil-water mixtures and highly emulsified oil-water dispersions under gravity alone, achieving exceptionally high flux (3693 L·m−2·h−1) and efficiency (99 %), while being recyclable. The aerogel membrane also displays stability and universality, making it effective in removing oil droplets from water in corrosive environments such as acids, salts and alkalis. Furthermore, TMAdf aerogel membrane shows long-lasting antibacterial properties (photothermal sterilization up to 6 times) and biodegradability (completely degraded after 50 days in soil). This study presents new ideas and insights for the fabrication of multifunctional membranes for oil-water separation.

Synthesis, Characterization, and Fabrication of Nickel Metal-Organic Framework-Incorporated Polymer Electrolyte Membranes for Fuel-Cell Applications.

Proton-conducting sulfonated polymer metal-organic framework (MOF)-based composite membranes were synthesized by anchoring the nickel MOF (Ni-MOF) to the aromatic sulfonated polymer backbone. In this work, we sulfonated two different polymers, poly(1,4-phenylene ether ether sulfone) (PEES) and poly ether ether ketone (PEEK), with a controllable sulfonation degree, and the synthesized Ni-MOF was incorporated into the sulfonated polymers to prepare a polymer electrolyte membrane. The effect of an MOF as a pendant moiety on the polymer backbone had a significant effect on properties such as water uptake, thermal, mechanical, and oxidative stabilities, swelling ratio, ion-exchange capacity (IEC), morphology, proton conductivity, and fuel-cell performance. The presence of an MOF structure enhanced the water retention capacity of the composite membranes. Adding Ni-MOF to the composite membrane improved the fuel-cell performance by increasing the OCV and power density. Among the synthesized electrolytes, the 3 wt % Ni-MOF-incorporated sPEEK membrane displayed a power density of 319 mW/cm2 with a cell voltage of 0.79 V, which was higher than the pure sulfonated polymer. Thus, the developed composite membranes are suitable for fuel-cell applications.

Local delivery of methotrexate/glycyrrhizin-loaded hyaluronic acid nanofiber for the management of oral cancer

The challenges in treating oral cancer include the limited effectiveness and systemic side effects of conventional chemotherapy and radiation therapy. Hyaluronic acid (HA) based Glycyrrhizin (GL) and Methotrexate (MT) loaded localized delivery systems, specifically nanofiber (NF) based platforms, were developed to address these challenges. The electrospinning method was used for the successful fabrication of a homogenous NF membrane and characterized for morphology, drug entrapment efficiency, tensile strength, and ex-vivo mucoadhesive study. Also, it was evaluated for in-vitro drug release profile, ex-vivo drug permeability, in-vitro anti-inflammatory, apoptosis assay by MTT and flow, and against specific cell lines in order to determine their potential for therapeutic use. Superior tensile breaking force (50 g), mucoadhesive strength of 153 gm/cm2, drug permeability, and releasing properties of designed NF, making them perfect requirements for oral cavity delivery. The anticancer potential of MT in the MTT assay and flow cytometry analysis was significantly increased in oral epidermal carcinoma cell (KB cell) for drug-loaded NF with 63.97 ± 1.99 % apoptosis, at 24 h. With these incorporated, GL with MT in NF had an anti-inflammatory potential, also demonstrated in-vitro and in-vivo. In the Ehrlich Ascites Carcinoma (EAC) induced mice model, the optimal formulation’s shows better potential for tumor regression when comparing the developed NF formulation to the drugs. Experimental results show that by lowering mucositis-related inflammation and enhancing the effectiveness of oral cancer treatment, a developed nanofiber-based local drug delivery system offers a feasible strategy for managing oral cancer.

Phosphatidylserine and/or Sialic Acid Modified Liposomes Increase Uptake by Tumor-associated Macrophages and Enhance the Anti-tumor Effect.

DOX liposomes have better therapeutic effects and lower toxic side effects. The targeting ability of liposomes is one of the key factors affecting the therapeutic effect of DOX liposomes. This study developed two types of targeted liposomes. Sialic acid (SA)-modified liposomes were designed to target the highly expressed Siglec-1 receptor on tumor-associated macrophages surface. Phosphatidylserine (PS)-modified liposomes were designed to promote phagocytosis by monocyte-derived macrophages through PS apoptotic signaling. In order to assess and compare the therapeutic potential of different targeted pathways in the context of anti-tumor treatment, we compared four phosphatidylserine membrane materials (DOPS, DSPS, DPPS and DMPS) and found that liposomes prepared using DOPS as material could significantly improve the uptake ability of RAW264.7 cells for DOX liposomes. On this basis, normal DOX liposomes (CL-DOX) and SA-modified DOX liposomes (SAL-DOX), PS-modified DOX liposomes (PS-CL-DOX), SA and PS co-modified DOX liposomes (PS-SAL-DOX) were prepared. The anti-tumor cells function of each liposome on S180 and RAW264.7 in vitro was investigated, and it was found that SA on the surface of liposomes can increase the inhibitory effect. In vivo efficacy results exhibited that SAL-DOX and PS-CL-DOX were superior to other groups in terms of ability to inhibit tumor growth and tumor inhibition index, among which SAL-DOX had the best anti-tumor effect. Moreover, SAL-DOX group mice had high expression of IFN-γ as well as IL-12 factors, which could significantly inhibit mice tumor growth, improve the immune microenvironment of the tumor site, and have excellent targeted delivery potential.

A novel, green, and environmentally friendly PBS/nano-CaCO3 hybrid membrane

Biodegradable membrane materials can be degraded into small molecules under natural conditions, which can effectively alleviate the environmental pollution caused by the waste of traditional organic membrane materials. In this work, biodegradable poly (butylene succinate) (PBS)/nano-CaCO3 hybrid membranes has been prepared via non-solvent induced phase separation method by blending environmentally friendly nano-CaCO3 particles with PBS. The incorporation of nano-CaCO3 particles into the membrane leads to a notable enhancement in mechanical strength, from 1.03±0.05 MPa to 1.42±0.13 MPa, resulting in a substantial increase of approximately 37 %. Additionally, the introduction of these particles also contributes to a reduction in contact angle, from 63° to 56°. Consequently, the issue of inadequate mechanical strength and limited hydrophilicity of PBS membrane is effectively addressed. Moreover, the pure water permeance of membrane increases from 8.5 L·m−2·h−1·bar−1 to 89.3 L·m−2·h−1·bar−1, and the permeability is greatly improved. The permeance recovery rate of the membrane increases from 78 % to 95 %, and the anti-fouling performance is improved. In addition, PBS can be degraded after the service of PBS/nano-CaCO3 hybrid membrane, and CaCO3 particles are environmentally friendly. Therefore, the PBS/nano-CaCO3 hybrid membrane hybrid membrane prepared in this study is a green and environmentally friendly membrane material.

High ethane content enables efficient CO2 capture from natural gas by cryogenic distillation

Cryogenic CO2 capture technique is superior to other CO2 capture methods in terms of potential environmental protection, because it uses no chemical solvent or membrane materials that need regular replacement. However, the freezing problem of CO2 makes it difficult to achieve CO2 capture through simple gas–liquid separation, and the existing cryogenic CO2 capture techniques often require a specially designed separation equipment. In addition, cryogenic CO2 capture is generally considered a method with high energy consumption due to the need for refrigeration. This study proposes a cryogenic distillation-based CO2 capture method for natural gas with high ethane content, such as shale gas and oilfield associated gas. This method utilizes the azeotropic characteristics of CO2 and ethane to avoid CO2 freeze-out and the energy consumption for CO2 capture is minimized through process integration with natural gas liquefaction and ethane recovery. The proposed system uses the propane precooled mixed refrigerant process to provide the required refrigeration, and it is simulated in Aspen HYSYS and optimized by a combined method of a genetic algorithm and sequential optimization. The results show that the proposed process can remove up to 17 mol% of CO2 to less than 50 ppm. With extractive distillation, 99.50 % of the ethane in the feed gas is recovered with a purity of 99.50 mol%. The optimal results corresponding to the maximum allowable CO2 content to avoid its freeze-out (with a solubility margin of 500 ppm) show that when ethane content is 2–20 mol%, the specific power consumption of the system is about 0.43 kWh/Nm3(NG) with an exergy efficiency higher than 50 %. The proposed process achieves energy-saving and efficient CO2 capture method for natural gas with high ethane content.

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.

Synthesis of clay/Fe/ZSM-5 composite membrane for chromium (vi) removal from aqueous media and its electrochemical performance

The present study explores the potential use of a Clay/Fe/ZSM-5 zeolite membrane as an effective platform for Chromium (VI) filtration. The raw clay sourced from Wadi Haqil Ras Al-Khaimah-UAE was utilized for fabricating the clay support sintered at 1000°C. Clay powder with a granulometry range of 125 µm ≤ Φ ≤ 250 µm, was obtained through crushing and sieving with ASTM sieves and used to prepare the clay support. The Fe/ZSM-5 zeolite was synthesized via the hydrothermal method, using tetrapropylammonium bromide (TPABr) as an organic structure-directing template. The characterization of both the clay support sintered at 1000°C and Fe/ZSM-5 zeolite membrane was conducted through various techniques, including XRD, FTIR, FE-SEM coupled with EDS, and XPS analysis. Notably, the support exhibited a relatively high deionized water flux, stabilizing at 140 L.m−2.h−1 after 120 min of operation, indicating excellent permeability. FE-SEM observations confirmed that Fe/ZSM-5 consisted primarily of granular particles with an orthorhombic crystal lattice, aligning with its crystallinity demonstrated by XRD analysis. The filtration tests for Cr(VI) solutions, conducted using a flow loop designed for cross-flow filtration, demonstrated retention rates of 23 % and 40 % for the clay support and Fe/ZSM-5 zeolite membrane, respectively, after a working time of 120 min. These results suggest the potential of Fe/ZSM-5 zeolite as an effective alternative adsorbent for removing Cr(VI) from wastewater, showcasing outstanding performance in this application. The Clay support and Fe/ZSM-5 zeolite membrane materials were used as electrodes for cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in [Fe(CN)6]3-/4-/0.1 M KCl solution, and Fe/ZSM-5 zeolite membrane material exhibited high electrochemical charge transfer compared to the clay support material.

Sustainable membrane technology for water purification—Manufacturing, recycling and environmental impacts

Water pollution has become a serious threat to our ecosystem. Water contamination due to human, commercial, and industrial activities has negatively affected the whole world. Owing to the global demanding challenges of water pollution treatments and achieving sustainability, membrane technology has gained increasing research attention. Although numerous membrane materials have focused, the sustainable water purification membranes are most effective for environmental needs. In this regard sustainable, green, and recyclable polymeric and nanocomposite membranes have been developed. Materials fulfilling sustainable environmental demands usually include wide-ranging polyesters, polyamides, polysulfones, and recyclable/biodegradable petroleum polymers plus non-toxic solvents. Consequently, water purification membranes for nanofiltration, microfiltration, reverse osmosis, ultrafiltration, and related filtration processes have been designed. Sustainable polymer membranes for water purification have been manufactured using facile techniques. The resulting membranes have been tested for desalination, dye removal, ion separation, and antibacterial processes for wastewater. Environmental sustainability studies have also pointed towards desired life cycle assessment results for these water purification membranes. Recycling of water treatment membranes have been performed by three major processes mechanical recycling, chemical recycling, or thermal recycling. Moreover, use of sustainable membranes has caused positive environmental impacts for safe waste water treatment. Importantly, worth of sustainable water purification membranes has been analyzed for the environmentally friendly water purification applications. There is vast scope of developing and investigating water purification membranes using countless sustainable polymers, materials, and nanomaterials. Hence, value of sustainable membranes has been analyzed to meet the global demands and challenges to attain future clean water and ecosystem.