Physicochemical Properties Of Membranes Research Articles

Tailoring physicochemical properties of quaternized polystyrene-ethylene/butylene-styrene membrane for enhanced pervaporation desalination

Pervaporation offers unique advantages for desalination of hypersaline water using highly hydrophilic and selective membrane. Positively charged membrane is superior in repelling cations and preventing scaling through electrostatic repulsion. This study investigates the quaternization and crosslinking of block copolymer styrene-ethylene-butylene-styrene (SEBS) membrane and explores the potential of quaternized membrane for pervaporation desalination. A one-step immersion process was proposed to easily adjust the physicochemical properties of membrane using trimethylamine (TMA) and N,N,N′,N′-tetramethyl-1,6-hexanediamine (TMHDA) for ammonium grafting and crosslinking. Compared to the quaternization with TMA or TMHDA alone, the combination of TMA and TMHDA produces a synergistic effect, improving crosslinking efficiency and facilitating the grafting reaction. This results in high ion exchange capacity (IEC) values and a transformation of microphase separation structure with more interconnected hydrophilic domains. An ultrahigh water permeability coefficient of 0.6 × 106–1.2 × 106 Barrer and highly intrinsic salt rejection were obtained in treating 3.5–20 wt% NaCl solution. The thin film composite QEBS/nylon membranes showed a superior water flux of 116.5 kg·m−2·h−1 and salt rejection of >99.99 % in desalinating 5 wt% NaCl solution at 85 °C. Additionally, the membrane exhibited excellent long-term performance stability and resistance to acid and alkali environment, showing great potential for desalination of hypersaline water.

Divalent cations promote huntingtin fibril formation on endoplasmic reticulum derived and model membranes

Huntington's Disease (HD) is caused by an abnormal expansion of the polyglutamine (polyQ) domain within the first exon of the huntingtin protein (htt). This expansion promotes disease-related htt aggregation into amyloid fibrils and the formation of proteinaceous inclusion bodies within neurons. Fibril formation is a complex heterogenous process involving an array of aggregate species such as oligomers, protofibrils, and fibrils. In HD, structural abnormalities of membranes of several organelles develop. In particular, the accumulation of htt fibrils near the endoplasmic reticulum (ER) impinges upon the membrane, resulting in ER damage, altered dynamics, and leakage of Ca2+. Here, the aggregation of htt at a bilayer interface assembled from ER-derived liposomes was investigated, and fibril formation directly on these membranes was enhanced. Based on these observations, simplified model systems were used to investigate mechanisms associated with htt aggregation on ER membranes. As the ER-derived liposome fractions contained residual Ca2+, the role of divalent cations was also investigated. In the absence of lipids, divalent cations had minimal impact on htt structure and aggregation. However, the presence of Ca2+ or Mg2+ played a key role in promoting fibril formation on lipid membranes despite reduced htt insertion into and association with lipid interfaces, suggesting that the ability of divalent cations to promote fibril formation on membranes is mediated by induced changes to the lipid membrane physicochemical properties. With enhanced concentrations of intracellular calcium being a hallmark of HD, the ability of divalent cations to influence htt aggregation at lipid membranes may play a role in aggregation events that lead to organelle abnormalities associated with disease.

Insights on the G protein-coupled receptor helix 8 solution structure and orientation using a neurotensin receptor 1 peptide.

G-protein coupled receptors (GPCRs) are the largest class of membrane proteins encoded in the human genome with high pharmaceutical relevance and implications to human health. These receptors share a prevalent architecture of seven transmembrane helices followed by an intracellular, amphipathic helix 8 (H8) and a disordered C-terminal tail (Ctail). Technological advancements have led to over 1000 receptor structures in the last two decades, yet frequently H8 and the Ctail are conformationally heterogeneous or altogether absent. Here we synthesize a peptide comprising the neurotensin receptor 1 (NTS1) H8 and Ctail (H8-Ctail) to investigate its structural stability, conformational dynamics, and orientation in the presence of detergent and phospholipid micelles, which mimic the membrane. Circular dichroism (CD) and nuclear magnetic resonance (NMR) measurements confirm that zwitterionic 1,2-diheptanoyl-sn-glycero-3-phosphocholine is a potent stabilizer of H8 structure, whereas the commonly-used branched detergent lauryl maltose neopentyl glycol (LMNG) is unable to completely stabilize the helix - even at amounts four orders of magnitude greater than its critical micellar concentration. We then used NMR spectroscopy to assign the backbone chemical shifts. A series of temperature and lipid titrations were used to define the H8 boundaries as F376-R392 from chemical shift perturbations, changes in resonance intensity, and chemical-shift-derived phi/psi angles. Finally, the H8 azimuthal and tilt angles, defining the helix orientation relative of the membrane normal were measured using paramagnetic relaxation enhancement NMR. Taken together, our studies reveal the H8-Ctail region is sensitive to membrane physicochemical properties and is capable of more adaptive behavior than previously suggested by static structural techniques.

Targeted Anthocyanin Enrichment of Cranberry Juice by Electrodialysis with Filtration Membranes: Impact of Filtration Membrane Physicochemical Properties and Predictive Statistical Models.

To optimize cranberry juice enrichment, correlation between physicochemical properties of filtration membranes (FM) and anthocyanin migration was investigated during electrodialysis with filtration membranes (EDFM) using redundancy (RDA) and multivariate regression (MRGA) analyses. Six polyether sulfone (PES) and polyvinylidene fluoride (PVDF) membranes with molecular weight cut-offs between 150 and 500 kDa, commercially available at large scale, were characterized in terms of nine physicochemical characteristics and used for EDFM. The highest migration of total anthocyanin was obtained with PVDF 250 kDa, with a global migration rate of 3.5 ± 0.4 g/m2·h. RDA showed that two FM properties (mesopore porosity and hydrophilic porosity) were significantly negatively correlated to the anthocyanin's migration and explained 67.4% of their total variation in migration. Predictive MRGA models were also developed for each anthocyanin based on these significant FM properties. A combination of intermolecular interactions may lead to binding in a cooperative and synergistic mode and hinder the anthocyanin migration.

Pervaporation Membranes Based on Polyelectrolyte Complex of Sodium Alginate/Polyethyleneimine Modified with Graphene Oxide for Ethanol Dehydration.

Pervaporation is considered the most promising technology for dehydration of bioalcohols, attracting increasing attention as a renewable energy source. In this regard, the development of stable and effective membranes is required. In this study, highly efficient membranes for the enhanced pervaporation dehydration of ethanol were developed by modification of sodium alginate (SA) with a polyethylenimine (PEI) forming polyelectrolyte complex (PEC) and graphene oxide (GO). The effect of modifications with GO or/and PEI on the structure, physicochemical, and transport characteristics of dense membranes was studied. The formation of a PEC by ionic cross-linking and its interaction with GO led to changes in membrane structure, confirmed by spectroscopic and microscopic methods. The physicochemical properties of membranes were investigated by a thermogravimetric analysis, a differential scanning calorimetry, and measurements of contact angles. The theoretical consideration using computational methods showed favorable hydrogen bonding interactions between GO, PEI, and water, which caused improved membrane performance. To increase permeability, supported membranes without treatment and cross-linked were developed by the deposition of a thin dense layer from the optimal PEC/GO (2.5%) composite onto a developed porous substrate from polyacrylonitrile. The cross-linked supported membrane demonstrated more than two times increased permeation flux, higher selectivity (above 99.7 wt.% water in the permeate) and stability for separating diluted mixtures compared to the dense pristine SA membrane.

Bacterial Glycolipid Acting on Protein Transport Across Membranes.

The process of protein transport across membranes involves a variety of factors and has been extensively investigated. Traditionally, proteinaceous translocons and chaperones have been recognized as crucial factors in this process. However, recent studies have highlighted the significant roles played by lipids and a glycolipid present in biological membranes in membrane protein transport. Membrane lipids can influence transport efficiency by altering the physicochemical properties of membranes. Notably, our studies have revealed that diacylglycerol (DAG) attenuates mobility in the membrane core region, leading to a dramatic suppression of membrane protein integration. Conversely, a glycolipid in Escherichia coli inner membranes, named membrane protein integrase (MPIase), enhances integration not only through the alteration of membrane properties but also via direct interactions with membrane proteins. This review explores the mechanisms of membrane protein integration mediated by membrane lipids, specifically DAG, and MPIase. Our results, along with the employed physicochemical analysis methods such as fluorescence measurements, nuclear magnetic resonance, surface plasmon resonance, and docking simulation, are presented to elucidate these mechanisms.

Concentration-Dependent Effects of Curcumin on Membrane Permeability and Structure.

Growing evidence suggests that many bioactive molecules can nonspecifically modulate the physicochemical properties of membranes and influence the action of embedded membrane proteins. This study investigates the interactions of curcumin with protein-free model membranes consisting of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and DOPC with cholesterol (4/1 mol ratio). The focus is on the capability of curcumin to modify membrane barrier properties such as water permeability assayed through the droplet interface bilayer (DIB) model membrane. For pure DOPC, our findings show a concentration-dependent biphasic effect: a reduction in water permeability is observed at low concentrations (up to 2 mol %), whereas at high concentrations of curcumin, water permeability increases. In the presence of cholesterol, we observed an overall reduction in water permeability. A combination of complementary experimental methods, including phase transition parameters studied by differential scanning calorimetry (DSC) and structural properties measured by attenuated total reflectance (ATR)-FTIR, provides a deeper understanding of concentration-dependent interactions of curcumin with DOPC bilayers in the absence and presence of cholesterol. Our experimental findings align with a molecular mechanism of curcumin's interaction with model membranes, wherein its effect is contingent on its concentration. At low concentrations, curcumin binds to the lipid-water interface through hydrogen bonding with the phosphate headgroup, thereby obstructing the transport of water molecules. Conversely, at high concentrations, curcumin permeates the acyl chain region, inducing packing disorders and demonstrating evidence of phase separation. Enhanced knowledge of the impact of curcumin on membranes, which, in turn, can affect protein function, is likely to be beneficial for the successful translation of curcumin into effective medicine.

Porous Zn-TCPP interlayer with active reaction sites modulates membrane physicochemical properties to improve nanofiltration performance

For nanofiltration (NF) membranes, constructing the interlayer between the substrate and polyamide (PA) layer could balance the trade-off effect between the selectivity and permeability. However, the influencing mechanism of the interlayer to the PA layer is mostly indirect, and how to regulate the physicochemical properties of the PA layer to improve the membrane property remains to be investigated. In this study, porous Zn-TCPP nanosheets with active reaction sites were used to construct interlayer and directly participated in interfacial polymerization (IP) reaction through the edge COOH of nanosheets reacting with piperazine (PIP) to further regulate PA layer physicochemical properties. Controlling the amount of nanosheets involved in the reaction, NF membranes with striated Turing structures, higher negatively charged surface and larger effective filtration area were obtained. The NF membrane permeability with Zn-TCPP interlayer was significantly improved by 123 % while the Cl−/SO42− selectivity was greatly enhanced to 72.69, meanwhile it showed excellent performance stability. This study presents a new perspective that the interlayer can modulate the NF membrane physicochemical properties to improve its performance by directly participating in the IP reaction.

Simple and low-cost anion exchange membrane based on PVA and PDC for acid recovery by diffusion dialysis

Anion exchange membranes were prepared by a simple method on the basis of polyvinyl alcohol (PVA) and 1,4-Piperazinedicarboxaldehyde (PDC). A network structure was formed in the membranes by cross-linking between PVA and PDC. The mechanical stability and acid stability the prepared membranes was tested. The TS value was tested as 17.5–37.8 MPa, Eb was 120.4–54.7% and the mass retention in the acid environment was 98.4–97.2%. Meanwhile, the physicochemical properties of membranes, such as thermogravimetric analysis (TGA), water absorption (WR), ion exchange capacity (IEC) and linear expansion rate (LER). WR was 106.9–136.7%, IEC was 1.03–1.55 mmol/g, and LER was 37.93–33.33%. In practical application, diffusion dialysis (DD) performance of membranes were tested. In DD test, the acid dialysis coefficient (UH+) was 17.5–27.9 × 10−3 m/h, and the separation factor (S) was 31.25–23.38. The UH+ and S were all higher than commercial membrane DF-120 (UH+ is 9 × 10−3 m/h and S is 18.00). Results were shown that the comprehensive properties of membranes were good. Therefore, the prepared membranes had broad application prospects for acid recovery by diffusion dialysis.

Evaluation of Lipids for the Study of Photosynthetic Membranes.

The biological role of lipids goes far beyond the formation of a structural membrane bilayer platform for membrane proteins and controlling fluxes across the membranes. For example, in photosynthetic thylakoid membranes, lipids occupy well-defined binding niches within protein complexes and determine the structural organization of membrane proteins and their function by controlling generic physicochemical membrane properties. In this chapter, two-dimensional thin-layer chromatography (2D TLC) and gas chromatography (GC) techniques are presented for quantitative analysis of lipid classes and fatty acids in thylakoid membranes. In addition, lipid extraction methods from isolated thylakoid membranes and leaves are described together with a procedure for the derivatization of fatty acids to fatty acid methyl esters (FAME) that is required for GC analysis.

Transformation of brackish water Reverse Osmosis membranes to nanofiltration & ultrafiltration membranes by NaOCl treatment: Kinetic and characterization studies

Thin Film Composite (TFC) Reverse Osmosis (RO) membranes used in desalination, reach their End-of-Life (EoL) due to fouling and chemical degradation and pose disposal problem. Their lifetime can be increased by converting them into Ultrafiltration (UF) or Nanofiltration (NF) membranes. The present work demonstrates a systematic methodology in terms of ‘ppm-h/ppm∙h exposure’ to chemically convert brackish water RO membranes into NF and subsequently into UF membranes using sodium hypochlorite (NaOCl). Post-performance studies of pure water flux, monovalent and bivalent salt rejection are carried at each treatment level. RO membrane has transformed into NF at 3000–3 ppm-h, 2000–6 ppm-h, 3000–6 ppm-h and in to UF membrane beyond 10000–3 ppm-h. Gradual changes in physicochemical properties of membrane during conversion are ascertained from Scanning Electron Microscope (SEM), Atomic Force Microscopy (AFM), Attenuated Total Reflection – Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-Ray Photoelectron Spectroscopy (XPS), contact angle, zeta potential etc. The rate of chlorination of polyamide is derived using XPS elemental data from initial stages of NaOCl exposure, and rate of hydrolysis from the membrane resistance, and pH. The overall rate equation is combination of both. The membrane thickness calculated from the kinetics match with experimental data. This study gives account of depolymerization of polyamide upon NaOCl exposure (ppm-h) which can be useful in chemical recycling/treatment of EoL membranes on a plant scale.

STRUCTURAL AND FUNCTIONAL ASPECTS OF THE INTERACTIONS BETWEEN MEDICAL POLYMERS AND THE LIPOSOMS AND BACTERIAL CELLS

Polymers are widely applied as drug delivery systems and implant coatings. The review is devoted to the mechanisms of interaction of biomedical polymers with model cell membranes (liposomes) and real biological objects - bacterial cell surfaces. A comparative analysis of the composition, structure and surface charge of different types of biological membranes has been outlined. We consider the main methods and approaches for studying the effect of polymers on the structure and physico-chemical properties of membranes to uncover adsorption, defects in the bilayer, violations of the integrity of the bilayer, changes in cell morphology, etc. The correlation between the observed effects on model and real objects is analyzed. One of the important tasks of the review is to discover the key polymer’s characteristic (structure, size, charge, etc.) for the design of new high-molecular compounds with specified biological properties.

Graphene oxide composited with different size of organic molecules for hydrogen isotopic water separation in membrane distillation

Developing an efficient light water/tritiated water (H2O/HTO) separation process to meet environmental regulations is important in the nuclear energy field. The membrane distillation processes for the separation of H2O/D2O (deuteriated water), which is usually served as the laboratory model process for H2O/HTO separation, showed good separation performance with graphene oxide (GO)-based membranes. Here, the approach to enhance the H2O/D2O separation performance was explored through regulating interlayer spacing and physicochemical properties of membranes, for which two types of GO membranes were prepared and applied in air-gap membrane distillation: (i) small molecules of urea (UR) or ethanediamine (EDA) were cross-linked with GO platelets to obtain GO-framework (GOF) membranes designated as GO-UR or GO-EDA with varied interlayer spacing. The GO-EDA membrane with a permeation flux of 0.95 L·m−2·h−1 gave higher separation performance than the pristine GO membrane; (ii) macromolecules of hydrophilic polyvinyl alcohol (PVA) or hydrophobic polymethyl methacrylate (PMMA) were intercalated into GO laminates to adjust interlayer spacing and physicochemical properties of membranes. The resultant GO-PVA membrane exhibited a higher permeation flux of 0.94 L·m−2·h−1 and similar separation factor compared with the pristine GO membrane. Moreover, long-term process stability of H2O/D2O separation in membrane distillation was demonstrated using GO-EDA membrane for a 28-h process. Therefore, the results demonstrated that regulating interlayer spacing and physicochemical properties of membranes can provide a facile route to improve performance of GO-based membrane distillation processes for the separation of H2O/D2O, which may be applied to H2O/HTO separation process needed for the treatment of tritiated water in the nuclear energy field.

Insight into polydopamine coating on microfiltration membrane with controlled surface pore size for enhanced membrane rejection

Membrane modification with polydopamine (PDA) is a common practice to enhance membrane selectivity and improve membrane compatibility with nanoparticles or thin films. Depending on the membrane surface properties, dopamine can deposit or penetrate into microporous membranes, leading to alteration in the membrane's physicochemical properties and consequently its performance. In this study, microfiltration (MF) polyethersulfone membranes with varying surface pore sizes were fabricated by manipulating the precasting time (solvent evaporation time of 3s, 15s, 30s and 60s) prior to non-solvent induced phase separation (NIPS) process. Notably, the coating of PDA slightly reduced the membrane's surface pore size and membrane's porosity. M60 membrane which possessed the smallest mean surface pores (∼300 nm), exhibited PDA clusters predominantly formed on top of the membrane surface. With an increase in surface pore size, dopamine can penetrate the porous structure of the MF membrane, leading to the polymerization of dopamine into PDA aggregates on both the membrane surface and inner pores. The M30 membrane had the largest surface pore size (∼500 nm), showing the formation of large PDA globules in the finger-like pores. The membrane (M30P) experienced significant narrowing of the inner pores, resulting in reduced water permeability. Overall, all PDA-coated membranes exhibited improved sucrose rejection (85–95%) compared to the uncoated ones (64–83%). These finding provides insight into the polymerization mechanism of dopamine on porous membranes prior to the incorporation of nanomaterials or thin film coating.

Mechanism of membrane formation from mixing cellulose acetate and carbon quantum dots together in different solvents

BackgroundThe separation performance of a membrane mainly depends on its morphology. Casting solutions formed by different solvents have different membrane formation mechanisms, resulting in the formation of membrane with different morphology and pores. MethodsCA with/without CQDs was dissolved in various solvents, using water as non-solvent to prepare CA membrane through non-solvent induced phase separation (NIPS). The dynamic behavior of membrane formation was investigated using the dope viscosity, optical microscope observation of non-solvent penetration into the casting film, and light transmittance. However, the thermodynamic behavior was demonstrated by the phase diagram and FTIR-microscopy. Significant findingsCQDs addition and suitable solvents can tailor the physicochemical properties of membrane through its formation. When CQDs were added to different solvents dissolved CA dope, the surface porosity and pore size of the membranes increased while skin layer thickness decreased. In addition to viscosity, the kinetic behavior of membrane formation was also affected by the affinity between solvent and non-solvent. FTIR-microscopy revealed that the time required for phase separation of the 2P system was longer than that of the DMSO system. This is due to the higher viscosity of the 2P system.

Membrane reactors for hydrogen generation: From single stage to integrated systems

The excessive production of carbon dioxide, the greenhouse effect, and the resulting global warming due to the use of fossil fuels have prompted governments, industry, and researchers toward renewable and clean energy sources. Hydrogen has emerged as a novel carbon neutral energy carrier with the highest specific energy content. Production, storage, distribution, and utilization of hydrogen are rapidly increasing. In this context, the use of hydrogen in power plants, fuel cells and internal combustion engines is constantly being developed. However, widespread use of hydrogen requires its sustainable production at low cost and under high purity conditions, which is the subject of further research. Hydrogen separation using membrane reactors is not a new concept; however, it has gained special attention in the last decades and represents a relevant and promising option to potentially overcome the above mentioned problems. This review examines advances in industry and research in hydrogen utilization, hydrogen production using membrane reactors, the nature and physicochemical properties of membranes, and the various configurations of membrane reactors. The effects of membrane reactors on the interplay of temperature, pressure, reactant conversion, hydrogen production, and thermodynamic equilibrium are explained, and the results are compared with those of conventional reactors. Finally, fuel cells, solar collectors, and their integrability into membrane reactors are discussed.

Engineering fast water-selective pathways in graphene oxide membranes by porous vermiculite for efficient alcohol dehydration

Graphene oxide (GO) lamellar membranes with well-aligned architecture hold promising potential for molecular separations. However, the tortuous transport pathways and weak interlamellar interactions between stacked GO nanosheets cause low flux and poor stability, which are major drawbacks for their practical applications. Herein, we report a strategy to engineer fast and robust water-selective pathways within GO-based lamellar membranes by porous vermiculite (PVMT), a naturally layered magnesium aluminosilicate. PVMT nanosheets conferred abundant in-plane pores, which decreased the tortuosity and shortened the mass transport distance inside lamellar membranes. Meanwhile, PVMT nanosheets enhanced the hydrophilicity and fixed the interlayer distance, contributing to robust water-selective transport. The physicochemical properties of membranes, such as thickness and hydrophilicity, were manipulated by the loading amount of PVMT nanosheets. The resulting lamellar membranes exhibited excellent n-butanol dehydration performance with a permeation flux of 9554 g m−2 h−1 and a separation factor of 2678, which increased by up to 91% and 328% compared to pristine GO/PTFE membranes. Moreover, membranes remain stable for 192 h operation. Our study may stimulate further research on precise construction of mass-transfer pathways within lamellar membranes.

Highly adhesive CoFe2O4 nanoengineered PES membranes for salts and Naproxen removal and antimicrobial activities

CoFe2O4 nanoengineered membranes were developed, fully characterized, and evaluated for their effectiveness in removing salts and Naproxen from aqueous solution. Unlike previous studies, interfacial interactions were quantified and used to explain the observed membrane characteristics in terms of water transport, solute rejection, and membrane physico-chemical properties. The addition of CoFe2O4 improved mechanical and rejection properties of PES membranes; inorganic salts and Naproxen were rejected by 80%. The solutes were rejected mainly by electrostatic exclusion rather than size exclusion. The observed salt rejection was best explained by the Donnan model as the main rejection mechanism and highlighted the role of valences on solute rejection. The solute rejection was due to size exclusion and electrostatic effects. The observed salt rejection through electrostatic interactions was best explained by the Donnan model as one of rejection mechanisms and highlighted the role of valences in solute rejection. Cross-sectional imaging revealed that the addition of 1 wt% CoFe2O4 led to formation of membranes with dense thick active layers with decreased pore sizes. Although this improved solute rejection, the modification negatively impacted hydraulic resistance where an increase in the pressure drop across the membrane was noted. The rejection of Naproxen was further improved by decrease in membrane-solute affinity interactions as the membranes became more hydrophilic upon nanoparticle addition. Further, nanoengineered membranes’ antimicrobial activities revealed inactivation of S. aureus bacteria under both light and dark conditions. CoFe2O4 nanoengineered membranes are suitable for desalination, bacterial disinfection, and wastewater reclamation. The membranes are expected to have a longer lifespan due to the improvement in adhesive properties and tensile strengths upon modification with nanoparticles.

Study of the physicochemical and transport performance of neat Matrimid 5218 membrane with nanoparticles: A molecular dynamics simulation

Our study employed Molecular dynamics (MD) simulations using BIOVIA Materials Studio 2021 software programs to analyze neat and mixed matrix membranes (MMMs) for their solubility behaviour, thermodynamics, mechanical properties, and separation properties. The d-space, followed by the Matrimid 5218 (MAT) membranes’ amorphous state, was enhanced by adding particles to their structure. Furthermore, Calix[4]arene (CA) particles lead to improved membrane physicochemical properties, such as fractional free volume (FFV), glass transition temperature (Tg), Young's Modulus (E), shear modulus (G), and bulk modulus (B), which are indicators of improved thermal resistance and transport capacity. Besides, the N2, CH4, and CO2 gases’ transport properties and performance of membrane structures were analyzed in terms of their diffusivity, solubility, permeability, and selective behaviours. Based on MC simulations, increasing pressure results in a significant increase in gas adsorption, and CO2 is more readily absorbed than N2 or CH4, thanks to the robust interaction between the CO2 molecule and membrane structures. There were significant improvements in the CO2 permeability of MMMs filled with 0.75% CA particles compared to the neat MAT. Moreover, the MMMs were found to have improved selectivity in CO2/N2 and CO2/CH4 in comparison with neat membranes. Lastly, the measuring results of transport properties indicated that the MAT-CA (0.75%) membrane is proper for industrial applications, including the treatment of natural gas.

Carboxylated Graphene Oxide (c-GO) Embedded ThermoPlastic Polyurethane (TPU) Mixed Matrix Membrane with Improved Physicochemical Characteristics.

Water is an important component of our life. However, the unavailability of fresh water and its contamination are emerging problems. The textile industries are the major suppliers of contamination of water, producing high concentrations of heavy metals and hazardous dyes posing serious health hazards. Several technologies for water purification are available in the market. Among them, the membrane technology is a highly advantageous and facile strategy to remediate wastewater. Herein, the distinguished combination of pore-forming agents, solvent, and nanoparticles has been used to achieve improved functioning of the polymeric composite membranes. To do so, graphene oxide (GO) was fabricated via Hummer's technique and GO functionalization using chloroacetic acid (c-GO) was performed. Thermoplastic polyurathane (TPU) membranes having different concentrations c-GO were made using the phase inversion technique. Scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) was used to examine surface morphology, chemical functionalities on membranes surfaces, and crystallinity of membranes, respectively. The temperature-dependent behavior of c-GO composite membranes has been analyzed using DSC technique. The water contact angle measurements were performed for the estimation of hydrophilicity of the c-GO based TPU membrane. The improved water permeability of the composite membrane was observed with increasing the c-GO concentration in polymeric membranes. c-GO was observed as a potential candidate that enhanced membrane physicochemical properties. The proposed membranes can behave as efficient candidates in multiple domains of environmental remediation. Furthermore, the improved dye rejection characteristics of proposed composite membranes suggest that the membranes can be best suited for wastewater treatment as well.