Blend Membranes Research Articles

Preparation of Poly(vinyl alcohol)/Silk Sericin Blend Membranes with Solvent Casting Method For Effective Removal of Remazol Black B

Preparation of Poly(vinyl alcohol)/Silk Sericin Blend Membranes with Solvent Casting Method For Effective Removal of Remazol Black B

Fabrication and characterization of TiO2/Fe2O3 nanocomposites incorporated on novel ternary polymer blends for effective lead removal

ABSTRACT Polymer membrane plays a vital role in water treatment. Removing heavy metals such as Pb, Cr, Hg, Zn, and Al are the main focus of recent research. The mixed matrix membrane is a current trend with more advantages than the blend membrane. The design of a ternary polymer membrane for the removal of Pb can neglect the drawbacks associated with the single or blend membrane, such as hydrophilicity, flexibility, mechanical strength, and, most significantly, they have better adsorption capacity. Thus, PEI/CS/PU as a ternary polymer blend can show a hydrophilic measurement of 66.5° after incorporating TiO2/Fe2O3 nanocomposites. The significant functional group confirmations, crystallinity, and elemental compositions were confirmed via FTIR, XRD, and XPS after casting the membrane through the phase inversion technique. Also, incorporating nanomaterials has played a vital role in increasing the thermal stability of prepared ternary membranes. Furthermore, the membrane showed a pore diameter of 1.893 m2/g by BET analysis. The significant functional groups such as ether, imide, polyols, hydroxyl groups, and carbohydrates have helped enhance the batch adsorption experiment of TiO2/Fe2O3@PEI/CS/PU. The TiO2/Fe2O3@PEI/CS/PU system is well fitted with Freundlich isotherm at R2 = 0.97577. Hence, TiO2/Fe2O3@PEI/CS/PU membrane can be a potential adsorbent for Pb removal from water sources.

Blended crosslinked polybenzoxazole (PBO) membranes derived from phenolphthalein-based polyamide and polyimide for CO2/CH4 gas separation

Designing membrane materials with excellent gas separation performance is always a goal of membrane researchers. However, to be able to deliver stable performance and maintain membrane integrity under actual working conditions, a membrane material must be mechanically strong. In the last two decades, thermally rearranged polybenzoxazole (TR-PBO) polymers exhibit out-standing gas transport properties and great anti-plasticization behavior. But the TR reaction often lead to catastrophic deterioration in roughness of the polymer. To overcome this problem, we developed a polymer blending system consisting of a phenolphthalein-based polyamide (PHA, 6FC-DAP) and polyimide (API, OH-6FDA-DAP). Because of their similar chemical structures and the formation of inter-molecular hydrogen bonds, homogenous polymer blended membranes were obtained at molar ratios from 1:3 to 3:1 of PHA and API. Importantly, the B11 (PHA to API molar ratio of 1:1) derived PBO-based membranes exhibited superior mechanical and gas separation performance compared to the B31 (PHA: API=3:1) and B13 (PHA: API=3:1) derived PBO-based membranes. Note that, when the blended membrane B11 was fully converted into PBO, its tensile strength and elongation at break are 5.89 times and 3.27 times higher than those of the API derived TR-PBO. In addition, the B11–350 and B11–400 (thermal treatment at 350 °C and 400 °C in air atmosphere for 2 h, respectively) were not plasticized at a CO2 pressure of 30 atm. The excellent mechanical properties with appealing gas separation properties of these TR-PBO polymers have potential for CO2 relative gas separation applications.

Self-Healing of Poly(vinyl Alcohol)/Poly(acrylic Acid)-Polytetrahydrofuran-Poly(acrylic Acid) Blend Boosted via Shape Memory.

The self-healable polymers that can repair physical damage autonomously to extend their lifetime and reduce maintenance costs are promising intelligent materials. However, utilizing shape memory to facilitate self-repair is unusual at present. In this work, a series of poly(acrylic acid)-polytetrahydrofuran-poly(acrylic acid) polymers (PAA-PTMG-PAA, diPAA-PTMG) are synthesized as a switching phase and healing accelerator to blend into poly(vinyl alcohol) (PVA). The water swelling rate of the blend is up to 400.0% at 1/1 molecular weight ratio of PTMG/PAA and 20.0 wt % blend ratio of diPAA-PTMG to PVA, and its crystallization is changed significantly under wet conditions. The blend membrane exhibits not only a good hydrothermal-response shape memory effect but also a favorable self-healing behavior. The tensile strength and elongation at break are 12.4 MPa and 320.0% after healing at 25 °C, respectively. In particular, the wound membrane can achieve a better self-healing effect with the assistance of shape memory at 37 °C, and the elongation at the break increased to 515.9% after healing. The membrane is not cytotoxic, so it will be a promising biomedical material.

Enhancing the performance of a modified poly(ether-b-amide) blend membrane by PAMAM dendritic polymer for separation of CO2/CH4

Novel dense membranes were fabricated by blending poly(ether-b-amid), Pebax 1657, as the matrix and a poly(amidoamine) dendritic polymer (PAMAM), as the modifier, to evaluate CO2/CH4 gases separation. The study investigated the effects of PAMAM loading, operating pressure, and temperature on gas permeability and CO2/CH4 pair-gas ideal selectivity. All the membranes were characterized using various analytical techniques, including ATR-FTIR, XRD, SEM, FESEM, DSC, AFM, Tensile Analysis, density, Aging, Stability pure gas permeation, and gas solubility tests. FTIR results confirmed the interaction of PEO and PA segments with PAMAM increased polymer crystallinity, which is in agreement with DSC, XRD, and Tensile Analysis results. The membrane containing 3 wt% PAMAM showed the highest FFV which along with facilitated transport of CO2 by PAMAM, resulted in the highest CO2 permeability equal to 56.9 Barrer at 2 bar and 30 °C (more than 30% higher than the neat Pebax membrane at the same condition). Furthermore, the addition of 1 wt% PAMAM to Pebax increased the CO2/CH4 selectivity to 22.8 at 8 bar and 30 °C (more than 78% higher than the neat Pebax membrane at the same condition). Increasing PAMAM loading and applied pressure resulted in the enhancement of gases solubility, and a better ideal selectivity was obtained, correspondingly, Also higher solubility of CO2 compared with CH4 was confirmed by solubility measurements. It was revealed that gas permeability in the membranes was primarily governed by gas solubility rather than diffusivity. The results demonstrate that the modifying Pebax membrane by PAMAM enhances the separation performance with a negligible change against aging and good stability, which confirms potential applications of Pebax/PAMAM membranes in gas separation processes.

Effect of Mixing Technique on Physico-Chemical Characteristics of Blended Membranes for Gas Separation

Polymer blending has attracted considerable attention because of its ability to overcome the permeability–selectivity trade-off in gas separation applications. In this study, polysulfone (PSU)-modified cellulose acetate (CA) membranes were prepared using N-methyl-2-pyrrolidone (NMP) and tetrahydrofuran (THF) using a dry–wet phase inversion technique. The membranes were characterized using scanning electron microscopy (SEM) for morphological analysis, thermogravimetric analysis (TGA) for thermal stability, and Fourier transform infrared spectroscopy (FTIR) to identify the chemical changes on the surface of the membranes. Our analyses confirmed that the mixing method (the route chosen for preparing the casting solution for the blended membranes) significantly influences the morphological and thermal properties of the resultant membranes. The blended membranes exhibited a transition from a finger-like pore structure to a dense substructure in the presence of macrovoids. Similarly, thermal analysis confirmed the improved residual weight (up to 7%) and higher onset degradation temperature (up to 10 °C) of the synthesized membranes. Finally, spectral analysis confirmed that the blending of both polymers was physical only.

Insight into alkaline stability of N-heteroatom on N-dimethylpiperidinium based anion exchange membranes (AEMs) for alkaline water electrolysis

Alkaline stability is the main obstacle for anion exchange membranes (AEMs) for alkaline electrolysers. In order to research the effect of N-heteroatom polymers on the alkaline stability of N-dimethylpiperidinium (DMP) based AEMs, in this work, nine kinds of blend membranes were prepared by blending poly (oxindole biphenylene) (POBP), poly (N-methylisatin biphenylene) (mPOBP) and poly (biphenyl 4-imidazolecarboxaldehyde) (PB4Im) with poly (aryl piperidine) polymers (PTP-85) at the ratio of 1:19, 1:9, and 1:4, respectively. Moreover, in the preliminary investigation of alkaline stability, we broke the limitation of the immiscibility of the blend membranes and performed a comparative investigation by the 1H NMR. Surprisingly, the obtained blend membranes showed a much higher degree of degradation than PTP-85 in terms of ex-situ alkaline stability. The alkali absorption of different N-heteroatom polymers in different concentrations of NaOH at 55 °C and 80 °C showed that the alkaline stability of blend membranes was lower with the increase of alkali absorption. The in-situ stability test also demonstrated that the performance of blend AEMs decreased significantly after in-situ durability test under the galvanostatic mode. These results showed that blending with N-heteroatom polymers could negatively affect the alkaline stability of DMP-based AEMs, providing insight into the relationship between N-heteroatom and stability of DMP-based AEMs.

Preparation and performance evaluation of Polycarbonate/Polysulfone blend membranes for removal of Bovine serum albumin from water

ABSTRACT Blend membranes of polycarbonate and polysulfone were studied for removal of bovine serum albumin (BSA) from water. The membranes were prepared by blending (1–10) wt.% of polysulfone with polycarbonate and then non-solvent induced phase separation (NIPS) of blend solutions. Structural analysis, thermal and tensile properties, water uptake, porosity, water contact angle, and morphological studies were conducted. Water treatment performance of membranes were tested in a crossflow system in terms of pure water flux, rejection, and fouling. BSA rejection value was improved from 85.65% to 92.88% for polycarbonate membrane in the presence of 10 wt.% polysulfone.

PI@TB blend membranes containing amorphous carbon for gas separation

This study employs the same diamine monomer to synthesize polyimide (PI) and Tröger’s Base-based polymers of intrinsic microporosity (TB), which exhibit infinite miscibility due to like-dissolves-like phenomenon. The TB and PI exhibit significantly different thermal decomposition temperatures, enabling the partial carbonization of TB at a lower temperature while retaining the favorable mechanical properties of PI. Consequentially, This work propose a novel method to prepare blend membranes with a partial amorphous carbon structure. These membranes have excellent gas separation performance, similar to that of carbon membranes, while also retaining the machinability of traditional polymer membranes. The molecular structure of the material is characterized using 1H NMR and FTIR spectra, while the microscopic morphology is observed through scanning electron microscopy. Molecular dynamics simulations confirm the compatibility of both polymers and explain the improved properties. Gas transportation measurement confirms that PI@TB blend membranes demonstrate significant improvement in gas separation performance compared to original membranes. Specifically, enhancements in the gas separation performance of CO2/CH4, H2/CH4, and O2/N2 systems have been observed, with the CO2/CH4 pair demonstrating the most remarkable improvements, surpassing the 2019 Robeson upper limit. This design strategy can be applied to produce blend membranes containing amorphous carbon that exhibit great potential for high-performance separation processes in the future.

Understanding hydrogen solubility and free volume characteristics in charge-transfer phthalonitrile prepolymer and polyimide blend membranes

The increasing demand for hydrogen production has necessitated the development of H2-selective membranes. Polyimides are excellent membrane materials for gas separation; however, commercial polyimides generally lack sufficient H2 selectivity due to their low H2 affinity. Understanding the relationship between gas transport properties and free volume microstructure is critical to advancing H2-selective membrane design. Herein, we report a facile material strategy to adjust the free volume characteristics and H2 separation performance via blending Matrimid (PI) and crosslinkable resorcinol-based phthalonitrile prepolymer (RPN) with electron donor/acceptor properties. The novel RPN30/PI70 membrane exhibits H2/N2 and H2/CO2 permselectivity of 1637 and 66.4, respectively, with H2 permeability of 2.7 Barrer in pure gas test, surpassing Robeson upper bounds (2008). The increased H2 permselectivity of RPN/PI membranes was attributed to the narrowed free volume size and distribution, giving rise to the considerably improved H2 solubility and selectivity of the blends. Moreover, the H2 permeability of crosslinked RPN30/PI70 membranes can be further improved via thermal treatment. The H2/CO2 mixed-gas test reveals that the H2 gas separation performance of the RPN30/PI70 membrane is influenced by plasticization effect and competitive sorption. This study demonstrates a new versatile strategy for designing high-performance hydrogen-selective polymeric membranes.

Deep eutectic solvent-based blended membranes for ultra-super selective separation of SO2

SO2 is a major atmospheric pollutant leading to acid rain and smog. As a new generation of green solvents, deep eutectic solvents (DESs) have been widely investigated for gas capture. Nevertheless, studies on DES-based membranes for SO2 separation are yet minimal. Herein, we devised polymer/DES blended membranes comprising 1-butyl-3-methyl-imidazolium bromide ([Bmim]Br)/diethylene glycol (DEG) DES and poly (vinylidene fluoride) (PVDF), and these membranes were firstly used for selective separation of SO2 from N2 and CO2. The permeability of SO2 reaches up to 17480 Barrer (0.20 bar, 40 ºC) in PVDF/DES blended membrane containing 50 wt% of [Bmim]Br/DEG (2:1), with ultrahigh SO2/N2 and SO2/CO2 selectivity of 3690 and 211 obtained, respectively, far exceeding those in the state-of-the-art membranes reported in literature. The highly-reversible multi-site interaction between SO2 and [Bmim]Br/DEG DES was revealed by spectroscopic analysis. Furthermore, the PVDF/DES blended membrane was also able to efficiently and stably separate SO2/CO2/N2 (2.5/15/82.5%) mixed gas for at least 100 h. This work demonstrates for the first time that [Bmim]Br-based DESs are very efficient media for membrane separation of SO2. The easy preparation, low cost and high performance enable polymer/DES blended membranes to be promising candidates for flue gas desulfurization.

Preparation and characterization of PSF/SPSF blended ultrafiltration membranes

Purpose This paper aims to improve the permeability and antifouling of polysulfone (PSF) ultrafiltration membranes, the PSF matrix was modified by incorporating sulfonated polysulfone (SPSF). Design/methodology/approach Systematic investigations were conducted on the synergistic effects of a pore-forming agent, coagulation bath temperature and SPSF doping in the casting solution on blended ultrafiltration membranes. The chemical composition of the membranes was analyzed using Fourier transform infrared spectroscopy. The morphology and surface roughness of the membranes were characterized using scanning electron microscopy and atomic force microscopy. The hydrophilicity of the membrane surface was analyzed using a contact angle meter. The permeability and antifouling properties of the blended membranes were also investigated through filtration experiments. Findings The results indicated that the blended ultrafiltration membranes demonstrated an optimal overall performance when PVP-K30 content was 5.0 Wt.%, coagulation bath temperature was 30°C and SPSF content was 2.4 Wt.%. In comparison to a pure PSF ultrafiltration membrane, there was a significant increase in pure water flux (390.7 L·m−2·h−1) by 2.2 times, while bovine serum albumin retention slightly decreased to 93.8%. In addition, the flux recovery rate improved by 2.1 times (71.4%) compared to that of the original PSF ultrafiltration membrane. Practical implications The method provided a simple and practical solution for improving the antifouling and permeability of PSF ultrafiltration membranes. Originality/value SPSF was anticipated to serve as an excellent modification additive for the preparation of ultrafiltration membranes with superior properties.

An Investigation into the Efficacy of Low Temperature and UV Irradiated Citric Acid Crosslinked Zein/PEO Electrospun Membranes for Wound Healing Using Human Dermal Fibroblast Cells

AbstractA key material capable of effective wound closure is a pertinent demand of the day. Citric acid (CA)‐based crosslinking involves pre‐crosslinking followed by post‐crosslinking at higher temperature. Unlike conventional higher temperature treatment, this piece of work discusses post‐crosslinking at low temperature or under UV irradiation of CAZein/Polyethylene oxide (PEO) blend membranes. A comparative analysis of the wound healing efficiency of both membranes was done. Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) results showed that UV crosslinked CA Zein/PEO has a fast thermal degradation and the folded structure of the protein perturbed during UV crosslinking. More than 60 % of porosity and water vapor transmission rate (WVTR) of 1500–2000 g m−2 day−1 for both membranes could facilitate faster exudate absorption and gas exchange through the wound site. Thermally crosslinked CA Zein/PEO stimulated 67 % more collagen production within 2 days compared to control cells. Percentage of wound closure is also high for thermally crosslinked CA Zein/PEO compared to UV crosslinked CA Zein/PEO. Though cytotoxicity evaluation confirmed the non‐cytotoxicity of both membranes, thermally crosslinked membrane proved as a better candidate for wound care management.

Polyimide blend metal–organic framework‐based mixed matrix membrane for gas separation: A review

AbstractPolyimide (PI), a glassy polymer, suffers from permeability–selectivity trade‐off and plasticization, which restrict its gas separation performance. Instead of exploring new materials, polymer blend and mixed matrix membrane (MMM) emerge as promising approaches in improving membrane gas separation efficiency attributed to their simplicity and cost efficiency. However, polymer immiscibility and polymer‐filler incompatibility are the main challenges encountered in these two approaches, respectively. Thus far, only limited reviews target the comparison between PI/glassy and PI/rubbery polymer blends. Besides, the review on improving the compatibility between polymer and filler in PI‐metal–organic framework (MOF) MMM is also lacking. Hence, this review aims to assess the gas separation characteristics of PI blended with glassy and rubbery polymers, focusing on the blend miscibility. It was discovered that the casting solvent's solubility parameter and solvent volatility play a part in governing the blend miscibility. Meanwhile, the efficiency of surface functionalization and ionic liquid addition in improving the polymer–filler compatibility in MMM is also reviewed. The wet method for filler incorporation demonstrates a more homogeneous filler dispersion within the membrane. Hence, its employment in MOF‐based MMM fabrication can be explored further.

Click chemistry‐based azide‐substituted polysulfone/alkynyl‐substituted sulfonated polyvinyl alcohol/nafion blend membranes for direct methanol fuel cells

AbstractAt present, commercial Nafion membrane is not suitable for proton exchange membrane used in direct methanol fuel cell (DMFC) due to the severe methanol permeation phenomenon. This work reported the preparation and characterization of azide‐substituted polysulfone (PSU‐N3) and alkynyl‐substituted sulfonated polyvinyl alcohol (SAPVA) crosslinked in the matrix of Nafion membrane base on click chemistry applied in DMFC. The compatibility between PSU‐N3 and SAPVA is promoted due to the formation of crosslinked network structure. Key properties, including dimensional stability, oxidative stability, mechanical behavior, methanol permeability and proton conductivity, are compared with those of the recast Nafion membrane. The prepared blend membranes exhibit lower methanol permeability due to the crosslinked network and well‐dispersed microphase structure of PSU‐PVA in the Nafion matrix. The proton selectivity of the Nafion‐PSU‐PVA‐3 membrane is 9.16 × 104 S s/cm3, much higher than that of the recast Nafion membrane (2.82 × 104 S s/cm3). In DMFC single cell tests, the maximum power density of the Nafion‐PSU‐PVA‐3 membrane is 4.6 mW/cm2, about 58.6% higher than that of the recast Nafion membrane. All the results indicate that the prepared blend membranes have the potential to be applied in DMFC.

Novel Ion-Exchange (Blend)-Membranes Based on Free Amines for All-Vanadium Redox Flow Batteries

For reaching the aim of a climate-neutral EU within the European Green Deal until 2050 several new innovations in different fields, especially in the field of renewable energies, are necessary [1]. One challenge which has to be overcome is the fluctuating nature of wind and solar energy and the associated storage and release of excess energy for stabilisation of the power-grid [2]. One promising technology in this regard is the All-Vanadium Redox Flow Battery (VRFB) in which Nafion-based membranes are usually utilised [3, 4]. However, due to high costs and a low H+/V selectivity there are many attempts to find alternative materials with better performance, lower crossover and reduced costs [5, 6].In this work we present a new aromatic, ether-free and side-chain containing polymer with free non-quaternised amine groups prepared by polyhydroxyalkylation. A new monomer was designed to improve the conductivity and morphology of the resulting membranes. The membranes show sufficient mechanical properties in the wet state and improved conductivity compared to commercially available free-amine based VRFB membranes. Blend membranes with a PBI derivative were produced to improve the mechanical properties in the dry state and the crossover of vanadium species.The above-mentioned membranes were characterised ex-situ by using EIS, NMR spectroscopy, TGA, DMA and permeability tests. In addition, first promising in-situ characterisations were performed in a VRFB single-cell test station.Literature[1] European Commission: The European Green Deal, Brussels, 2019; URL: https://ec.europa.eu/info/strategy/priorities-2019-2024/european-green-deal_de#documents, accessed: 21.11.2022.[2] Reihani, E; Motalleb, M; Ghorbani, R; Saad Saoud, L.: Load peak shaving and power smoothing of a distribution grid with high renewable energy penetration. Renewable Energy 2016, 1372 – 1379.[3] Düerkop, D; Widdecke, H; Schilde, C; Kunz, U; Schmiemann, A.: Polymer Membranes for All-Vanadium Redox Flow Batteries: A Review. Membranes 2021.[4] Guarnieri, M; Mattavelli, P; Petrone, G; Spagnuolo, G.: Vanadium Redox Flow Batteries: Potentials and Challenges of an Emerging Storage Technology. EEE Ind. Electron. Mag. 2016, 20 – 31.[5] Zeng, L; Zhao, T.S; Wei, L; Jiang, H.R; Wu, M.C.: Anion exchange membranes for aqueous acid-based redox flow batteries: Current status and challenges. Applied Energy 2019, 622 – 643.[6] Gubler, L.: Membranes and separators for redox flow batteries. Current Opinion in Electrochemistry 2019, 31 – 36.

Preparation of polysulfone based rubidium ion imprinted membrane and its selective adsorption and separation performance

A novel Rb+ imprinted membrane was fabricated via non-solvent inversion phase separation method by blending template RbCl, poly(styrene-co-4-hydroxylstyrene) (P(S-co-VPh)) and polysulfone, where the phenolic hydroxyl groups of P(S-co-VPh)) spontaneously coordinated with template Rb+ in the casting solution to form an imprinted Rb+ site. Gel permeation chromatography, FTIR and 1H NMR results indicated that the (P(S-co-VPh) had been synthesized successfully. The characterization of water contact angle, scanning electron microscope and membrane performance tests indicated that the blending membranes had better hydrophilicity, more porous structure and higher pure water flux. The adsorption behaviors of Rb+ on the blending membranes were investigated depending on the parameters of solution pH, temperature, ions interference, Rb+ concentration and contact time. The results indicated that the maximum Rb+ adsorption capacity can be obtained when the solution pH is 9.0, and low temperature is favorable for adsorption because it is an exothermic process. As compared to Na+, Ca2+, and Mg2+, K+ has the greatest ion interference effect, causing up to 58.1% decline in Rb+ adsorption capacity for non-imprinted membranes but only 7.4% for imprinted membranes. The adsorption process conforms to Langmuir isothermal model and pseudo-second-order kinetic model, and the theoretical maximum adsorption of Rb+ is 70.12 mg/g. Furthermore, the Rb+ imprinted membrane can be reused at least five times using 0.1 M HCl solution as the eluent, indicating that membrane has potential application value in the separation and extraction of rubidium.

Recovery of Bovine Serum Albumin from Wastewater Using a Cellulose Blend Membrane Derived from Chinese Herbal Medicine Residues

Recovery of Bovine Serum Albumin from Wastewater Using a Cellulose Blend Membrane Derived from Chinese Herbal Medicine Residues

Effect of TiO2 on Thermal, Mechanical, and Gas Separation Performances of Polyetherimide-Polyvinyl Acetate Blend Membranes.

Blend membranes consisting of two polymer pairs improve gas separation, but compromise mechanical and thermal properties. To address this, incorporating titanium dioxide (TiO2) nanoparticles has been suggested, to enhance interactions between polymer phases. Therefore, the objective of this study was to investigate the impact of TiO2 as a filler on the thermal, surface mechanical, as well as gas separation properties of blend membranes. Blend polymeric membranes consisting of polyetherimide (PEI) and polyvinyl acetate (PVAc) with blend ratios of (99:1) and (98:2) were developed via a wet-phase inversion technique. In the latter, TiO2 was incorporated in ratios of 1 and 2 wt.% while maintaining a blend ratio of (98:2). TGA and DSC analyses were used to examine thermal properties, and nano-indentation tests were carried out to ascertain surface mechanical characteristics. On the other hand, a gas permeation set-up was used to determine gas separation performance. TGA tests showed that blend membranes containing TiO2 had better thermal characteristics. Indentation tests showed that TiO2-containing membranes exhibited greater surface hardness compared to other membranes. The results of gas permeation experiments showed that TiO2-containing membranes had better separation characteristics. PEI-PVAc blend membranes with 2 wt.% TiO2 as filler displayed superior separation performance for both gas pairs (CO2/CH4 and CO2/N2). The compatibility between the rubbery and glassy phases of blend membranes was improved as a result of the inclusion of TiO2, which further benefited their thermal, surface mechanical, and gas separation performances.

Enhancing water flux and rejection performance through UV crosslinking: Optimization of surface modification of polyacrylonitrile (PAN)/acrylonitrile butadiene rubber (NBR) blend membrane using benzophenone as a crosslinking agent

Polyacrylonitrile (PAN)/acrylonitrile butadiene rubber (NBR) blend membranes were prepared by the phase inversion method using dimethylformamide as solvent. The blend membrane with a ratio of 85:15 was modified by ultraviolet (UV) radiation crosslinking of NBR using benzophenone as the crosslinking agent. The blend membrane was characterized through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), porosity, contact angel, tensile strength, pure water flux, and rejection measurements. The blend membrane showed an increased pure water flux and decreased BSA rejection. However, the addition of benzophenone and UV radiation reduced the porosity and flux of the membrane, while improving the tensile strength and BSA rejection. The response surface method (RSM) with central composite design (CCD) using Design Expert software was employed to optimize the modification conditions of the PAN/NBR blend membrane, and the suggested membrane contained 2.5 wt% benzophenone and was exposed to UV radiation for 2 h. This membrane showed a pure water flux of 95.3 L/m2h, BSA rejection of 81.1%, and a tensile strength of 4.01 MPa, which is a 45% increase in water flux compared to the neat PAN membrane while showing better rejection and preserving the desired mechanical properties.