Sulfonated Polyethersulfone Membranes Research Articles

Design of a high-performance polyaniline coated niobium dicarbide MXene nanostructure based electro-membrane system for improved nanoplastic separation

This study explores the development of advanced electro-membrane filtration by incorporating Nb-based MXene (Nb2CTx) to enhance nanoplastic (NP) separation and fouling mitigation. The presence of NPs in water results in less effective filtration, hence increasing cost, highlighting the urgent need for advanced removal technologies. Nb2CTx was incorporated at varying loadings, revealing significant alterations in their morphological, structural, and physiochemical properties. The performance evaluation using NP-rich suspensions demonstrated that the membrane with 5 % Nb2CTx loading (MS5) achieved a NP removal efficiency of 97.4 % and a water flux of 90.5 L.m−2.h−1, which was significantly higher than the pristine sulfonated polyether sulfone (SPES) membrane (18.9 L.m−2.h−1 with 94 % removal efficiency). The membrane was developed for an electro-membrane system using a sacrificial anode. The sacrificial anode allowed for multiple complex process to occur simultaneously, including electrocoagulation and membrane filtration. Polyaniline (PANI) coating was added to further increase the conductivity to allow for a more energy efficient process. The study underscores the importance of Nb2CTx loading and PANI modification in improving the filtration efficiency and fouling resistance. Furthermore, applied electric field resulted in enhanced operational sustainability of SPES membranes, offering a novel approach for water treatment applications.

Synthesized and characterized high‐performance and low‐cost zirconium phosphate‐additive sulfonated polyethersulfone membranes for PEMFC

AbstractIn this study, the preparation, characterization, and fuel cell performance tests of high‐performance and low‐cost zirconium phosphate (ZrP)‐additive sulfonated polyethersulfone (sPES) membranes, which may serve as a substitute for the commercial membrane used in proton exchange membrane fuel cell (PEMFC), were carried out. ZrP‐additive sPES membranes were prepared by solution casting method with different weight ratios (2.5%, 5%, and 9%). Fourier transform infrared (FTIR), water uptake capacity (WUc), dynamic mechanical analysis, ion exchange capacity (IEx), degree of hydration, impedance analysis, and oxidative stability were used to characterize the created membranes. Ultimately, single‐cell performance experiments were used to evaluate the membranes' performance in real fuel cell environments. ZrP additive improved the WUc, mechanical properties, IEx, and proton conductivity properties of the membrane. WUc of the membranes enhanced by approximately 94% at 80°C, while the proton conductivity augment by approximately 47% with 9% ZrP by weight. 0.97 meq g−1 IEx was obtained for the sPES, whereas it was obtained as 1.41 meq g−1 for sPES‐9ZrP. Oxidative stability experiments for 120‐h determined that all synthesized membranes had a stable structure, and their weight losses varied between 68% and 85%. The sPES‐9ZrP exhibited very high values at 0.6 V, resulting in a power density of 680 mW cm−2 and a current density of 1100 mA cm−2. The results obtained are quite promising, and sPES and ZrP in composite membrane structures have high synergy.

Eco-friendly, low-cost, and antibacterial PEM boosts microbial fuel cell performance: Power generation and wastewater treatment

The performance of microbial fuel cells (MFCs) relies significantly on the proton exchange membrane (PEM). While effective, commercial options like Nafion 117 are costly and possess inherent weaknesses. Improving methods of PEMs are generally used, requiring spending energy and money and causing harmful and toxic chemicals to enter the environment. This study introduces an innovative approach by enhancing sulfonated polyether sulfone (SPES) properties using Falcaria vulgaris extract, offering a simple, environmentally friendly, cost-effective solution. The resulting green functionalized SPES membranes (GFSPESs) were evaluated in dual-chamber MFCs for energy production and textile wastewater treatment. SPES membranes were fabricated through a phase inversion process and subsequently functionalized using dip-coating, heating, and UV irradiation. Comprehensive analysis, including FTIR, EDS, SEM, and XPS, investigated the physicochemical structure of the PEMs. The plant extract exhibited notable benefits, enhancing hydrophilicity, proton conductivity, and antibacterial capability of the PEMs. The MFC with GFSPES-12 achieved a peak power output of 86.3 mW/m2 and a maximum current of 327 mA/m2, surpassing the performance of Nafion 117 and the bare SPES membranes. GFSPES-12 also exhibited a maximum ion exchange capacity (1.89 meq/g) and proton conductivity (2.98 mS/cm). In textile wastewater treatment, the GFSPESs demonstrated improved COD removal (96.12 %) and higher coulombic efficiency (42.23 %). Notably, GFSPES-12 exhibited an antibacterial efficiency exceeding 93.5 %. These findings affirm the efficient functionality of GFSPES membranes in dual-chamber MFCs, offering a promising and sustainable alternative for energy production and wastewater treatment.

Removal of a cyanotoxins mixture by loose nanofiltration membranes applied in drinking water production

Cyanobacterial toxins may threaten human health if their levels in drinking water exceed certain thresholds. Therefore, it is important for water works that use raw water sources prone to cyanobacterial blooms to have efficient barriers against such toxins. Nanofiltration (NF) is one potential barrier. The efficacy and mechanism of removing four cyanotoxins, namely microcystins (MCs), cylindrospermopsin (CYN), saxitoxins (STXs), and anatoxin (ATX), were studied at bench-scale using NF membranes commonly applied in Norwegian drinking water facilities. The average removal of the different cyanotoxins under the tested operating conditions ranged from 15 % to 96 %. The membrane with the lowest molecular weight cut-off (MWCO) of 0.3 kDa made of polyamide (PA) was deemed the most suitable for the removal of all studied cyanotoxins. A gradual improvement of rejection observed with the 2 kDa cellulose acetate (CA) membrane was linked to the formation of fouling on the membrane surface. Sulfonated polyethersulfone (SPES) membranes with MWCO of 1 and 3 kDa could not efficiently and consistently remove cyanotoxins, except for MCs. The rejection of MCs over time was over 80 % by the SPES membranes during two days of filtration. The influence of pressure and pH as relevant operating parameters was evaluated. However, the analysis of the cyanotoxin concentrations in the permeate indicated that the investigated NF membranes alone would generally not be able to meet the WHO guidelines for drinking water during a severe cyanobacterial bloom. Thus, incorporating other water treatment technologies should be considered to effectively remove cyanotoxins.

Sulfonated Poly Ether Sulfone Membrane Reinforced with Bismuth-Based Organic and Inorganic Additives for Fuel Cells.

This research work focuses on developing a robust polymer electrolyte membrane (PEM) with high proton efficiency toward proton exchange membrane fuel cells (PEMFCs). In this study, poly ether sulfone (PES) was sulfonated by chlorosulfonic acid to yield sulfonated poly ether sulfone (SPES) followed by incorporation with bismuth-based additives such as bismuth trimesic acid (BiTMA) and bismuth molybdenum oxide (Bi2MoO6). The composite membrane was thoroughly investigated for its structural and physicochemical properties such as FT-IR, SEM, TGA, contact angle, water uptake, oxidative stability, ion-exchange capacity, and swelling ratio. Incorporation of additives into the polymer was confirmed by XPS and XRD analysis. The proton conductance of the pristine SPES is 4.19 × 10-3 S cm-1, whereas that of the composite membrane SPES/BiTMA-10 is 10 × 10-3 S cm-1 and that of SPES/Bi2MoO6-15 is 7.314 × 10-3 S cm-1; both the composite membranes exhibit higher proton conductivity than the pristine SPES membrane. The physicochemical characteristics and impedance measurements of the electrolyte reported can be viable to the PEM membrane.

Towards superior permeability and antifouling performance of sulfonated polyethersulfone ultrafiltration membranes modified with sulfopropyl methacrylate functionalized SBA-15

A non-solvent induced phase separation (NIPS) process was used to fabricate a series of sulfonated polyethersulfone (SPES) membranes blending with different concentrations of SBA-15-g-PSPA with the applications in the ultrafiltration (UF) process. SBA-15 was modified with 3-methacrylate-propyltrimethoxysilane (MPS) to form SBA-15-g-MPS. It was further modified with the charge tailorable polymer chains by reacting with 3-sulfopropyl methacrylate potassium salt. The nanoparticles were uniformly dispersed and finger-like channels were developed within the membrane. The adding of surface modified SBA-15-g-PSPA nanoparticles has significantly improved membrane water permeability, hydrophilicity, and antifouling properties. The pure water fluxes of the composite SPES membranes were significantly higher than the pristine SPES membrane. For the membrane containing 5% (mass) of SBA-15-g-PSPA (MSSPA5), the pure water flux was increased dramatically to 402.15 L∙m –2 ∙h –1 , which is ∼ 1.5 times that of MSSPA0 (268.0 L∙m –2 ∙h –1 ). The high flux rate was achieved with 3% (mass) of SBA-15 nanoparticles with retained high rejection ratio 98% for natural organic matter. The results indicate that the fashioned composite membrane comprising SBA-15-g-PSPA nanoparticles have a promising future in ultrafiltration applications.

Nanocomposite proton exchange membranes based on sulfonated polyethersulfone and functionalized quantum dots for fuel cell application

In this work novel nanocomposite proton exchange membranes were prepared using sulfonated polyethersulfone (SPES) with incorporation of ZnS functionalized quantum dots (FQDs) with a solution-casting method. The effect of functionalized groups (–COOH and NH2) of ZnS FQDs on the SPES membrane properties such as proton conductivity and performance was investigated. The highest proton conductivity of the nanocomposite membranes was achieved 116 mS/cm at 90°C. The nanocomposite membranes containing 2 wt% of ZnS FQDs displayed constant proton conductivity life time in 180 hours and fuel cell life time in 70 hours at 90°C, 98% RH, which confirmed strong interaction between functionalized group of ZnS FQDs and –SO3H groups of SPES. The power density of the SPES-ZnS FQDs nanocomposite membranes (DS of SPES: 45% and ZnS FQDs content: 2 wt%) obtained 0.53 W/cm2 in 98% RH, 0.5 V, and 90°C. The results confirmed that the prepared nanocomposite membranes with remarkable performance can be used as useful membranes for fuel cells.

Fabrication of sulfonated polyethersulfone ultrafiltration membranes with an excellent antifouling performance by impregnating with polysulfopropyl acrylate coated ZnO nanoparticles

Sulfonated polyethersulfone/sulfopropyl methacrylate membranes impregnated with the polysulfopropyl acrylate coated ZnO nanoparticles were developed using a non-solvent-induced phase separation recipe. The composite membranes offered much-enhanced hydrophilicity and improved porosity, which are critical for the excellent antifouling performance and high permeate flux. By adding polysulfopropyl acrylate modified ZnO, it achieved the maximum water flux of 420 Lm−2h−1 while maintained the natural organic matter rejection rate of 99% with an excellent flux recovery ratio up to 99% in the antifouling measurement. The results display that the impregnation of ZnO nanoparticles in the sulfonated polyethersulfone membrane can effectively increase the surface hydrophilicity which is essential for reducing the irreversible fouling with improved long-term performance and excellent recyclability.

Proton conducting membrane based on multifunctional interconnected copolymer containing 4,4′‐diaminodiphenylmethane‐aminoethyl piperazine with sulfonated polyethersulfone membrane for fuel cell application

AbstractThe facile fabrication of proton exchange membrane (PEM) by intermixing of aminoethylpiperazine monomer (AEP), diamino diphenylmethane (DDM) monomer, and AEP combine with varying compositions of DDM (2, 4, and 6 wt%) copolymer with sulfonated polyethersulfone (SPES) and polyamide‐imide (PAI) polymer matrix for fuel cell applications. The intermixing of AEP@DDM copolymer in the SPES/PAI matrix was confirmed by Fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction spectroscopy (XRD) techniques. The physicochemical performance of fabricated PEM was analyzed by water uptake, ion exchange capacity (IEC), swelling ratio, thermal degradation, hydrolytic degradation, chemical and mechanical properties. The intermixing copolymer (AEP@DDM) has significantly suppressed the thermal and hydrolytic deterioration of the PEM. Furthermore, the PAI had noteworthy to improve the thermal and chemical stability of the membranes significantly. The proton conductivity of the SPES/PAI/AEP@DDM (6%) membrane was found to be 5.68 × 10−4 S cm−1 which is 104% higher than the pristine SPES membrane. Besides, the selectivity of SPES/PAI/DDM (6%) was also enhanced up to 80.34% compared to pristine SPES membrane. The inclusion of AEP@DDM in SPES/PAI enhanced the proton conductivity and contributed to the membrane structure's uniformity, as revealed from morphological studies. The AEP@DDM copolymer modification of SPES/PAI membrane has shown good stability, physicochemical property and can be considered as a promising membrane material for fuel cell application.

Modification of Sulfonated Polyethersulfone Membrane as a Selective Adsorbent for Co(II) Ions.

In the current study, a variety of sulfonated polyethersulfone (SPES)-based ion-exchange membranes were prepared and utilized as efficient and selective solid adsorbents for the detection of Co(II) ions in aquatic solutions. SPES membranes were treated with a variety of cations at a 2:1 ratio overnight. The produced materials were assessed via XRD, FT-IR, SEM, and TGA analyses. The structure of these materials was confirmed by FT-IR and XRD, which also confirmed the inclusion of Na+, NH4+, and amberlite on the SPES surface successfully. TGA analysis showed that the thermal stabilities of these materials were enhanced, and the order of stability was NH4-SPES > SPES > Na-SPES > A-SPES. Furthermore, the efficiency of these modified membranes for the determination and adsorption of a variety of metal ions was also examined by the ICP-OES analytical technique. A-SPES expressed a powerful efficiency of adsorption, and it showed an efficient as well as quantitative adsorption at pH = 6. Moreover, A-SPES displayed the highest adsorption capacity of 90.13 mg/g for Co(II) through the Langmuir adsorption isotherm.

Enhancement of microbial fuel cell efficiency by incorporation of graphene oxide and functionalized graphene oxide in sulfonated polyethersulfone membrane

The present work examines, for the first time, the use of thiolated graphene oxide (TGO), in polyelectrolyte composite membranes as an effective approach to enhance the MFC performance. A new composite membrane based on a sulfonated polyethersulfone (SPES) hybrid with GO, sulfonated GO (SGO), and TGO was fabricated and assessed in MFC. The blend membranes were characterized with various techniques. The sulfhydryl (-SH) and sulfonic (-SO3H) groups enhanced the proton selectivity of the membrane and MFC performance. The MFC using the SPES/SGO1.8% composite membrane generated a power density of 66.4 mW/m2 which was double that produced by MFC using Nafion117 membrane in batch mode which lasted for 8 days. The SPES/SGO membrane was more selective towards H+ rather than other cations (K+, Na+, and Li+). This was also confirmed by the results of proton conductivity analysis, as the SPES/SGO1.8% membranes showed a value of 1.42 mS/cm which was higher than Nafion117 (1.3 mS/cm), SPES/TGO1.8% (1.25 mS/cm), SPES/GO1.8% (0.56 mS/cm), and SPES (0.32 mS/cm). The higher COD removal and coulombic efficiency were obtained in MFC with SPES/SGO membranes. In conclusion, it is our view that the new SPES/SGO and SPES/TGO membranes can be applied favorably in dual-chamber MFCs meeting their needs.

Highly selective heavy metal ions membranes combining sulfonated polyethersulfone and self-assembled manganese oxide nanosheets on positively functionalized graphene oxide nanosheets

This study presents the synthesis of a novel graphene oxide-manganese oxide (GO-MnO2) nanohybrid and its incorporation into sulfonated polyethersulfone (SPES) ultrafiltration (UF) membranes for wastewater treatment applications. The nanohybrid was first prepared by grafting ethylenediamine (ED) onto the edge of GO followed by direct mixing with the MnO2 nanosheets. The composite membranes were prepared via the phase inversion method and optimized by varying the concentration of the GO-MnO2 nanohybrid (0–6 wt%). The membranes were characterized using scanning electron microscopy, surface zeta potential, water flux, porosity, among others. The results showed that the pure water flux increased from 59.5 ± 2.5 L·m−2·h−1 in the pristine SPES membrane to 129.7 ± 4.1 L·m−2·h−1 in the SPGM4 (4 wt% GO-MnO2). Furthermore, the heavy metal ions rejection improved from 70.1, 49.1, and 55.8% for Cu2+, Zn2+, and Ni2+ ions, respectively, in the pristine SPES membrane to 81.1, 64.0, and 67.4% in the SPGM4 membrane. Also, the composite membranes revealed improvement in the anti-fouling properties over the pristine SPES membrane. For example, the SPGM4 membrane recovered 90.5 ± 2.9% of its initial flux compared to only 72.6 ± 3.1% in the pristine membrane after 4 cycles of heavy metal filtration and simple acid cleaning steps. Overall, the addition of GO-MnO2 nanohybrid enhanced the properties of the pristine SPES, creating new potential for such composite membranes in the wastewater treatment industry.

Proton exchange membrane based on graphene oxide/polysulfone hybrid nano-composite for simultaneous generation of electricity and wastewater treatment

Microbial fuel cell (MFC) is a combined technology for simultaneous generation of electricity and wastewater treatment. In MFC, the proton exchange membrane (PEM) is an essential component affecting electricity generation. In the current study, two proton exchange membranes, namely sulfonated polyethersulfone (SPES) and graphene oxide/sulfonated -polyethersulfone hybrid nanocomposite (GO-SPES), were prepared and characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The collected information confirmed the successful preparation of the membranes. Moreover, contact angle measurements, ion exchange capacity and degree of sulfonation of the prepared membranes were determined. The results showed that the introduction of GO nanoparticles into SPES membrane improved its proton exchange capability and resulted in better performance. The power density and the current generated from SPES membrane were 60 mW/m2 and 425 mA/m2, respectively. For GO-SPES, the obtained power density was 101.2 mW/m2 and the current was 613 mA/m2. Both membranes showed comparable chemical oxygen demand (COD) removal efficiency of about 80%; suggesting that the prepared membranes are working efficiently in wastewater treatment as PEMs in MFCs. As a final point, the performance of GO-SPES membrane was compared to the performance of the well-known Nafion® 117 membrane and the results were promising. To conclude, the GO-SPES membrane is an outstanding membrane for use as PEM in MFCs for simultaneous generation of electricity and wastewater treatment.

Sulfonated polyethersulfone membrane doped with ZnO-APTES nanoparticles with antimicrobial properties

In an attempt to mitigate membrane biofouling, the main limiting factor in membrane technology, ultrafiltration polyethersulfone (PES) membranes doped with zinc oxide nanoparticles (NPs) providing antimicrobial properties were fabricated. Synthesis of chlorsulfonated polyethersulfone (SPES-Cl) was based on modification of PES through sulfonation, followed by chlorination of -SO3H groups. The ZnO NPs were functionalized by (3-aminopropyl)triethoxysilane that enabled covalent bonding to polymer matrix, which was proved by XPS analysis. The membranes were examined for changes in permeability, antimicrobial properties, and leaching of ZnO NPs. Membrane with surface-functionalized ZnO NPs displayed permeability of ca. 260 L m−2 h−1 bar−1, comparable to the reference, while membrane doped with unmodified ZnO NPs exhibited permeability ca. 50 L m−2 h−1 bar−1. Membranes with ZnO NPs displayed antimicrobial properties, with unmodified ZnO NPs exhibiting inhibition zone of 2–3 mm for S. aureus and that for surface-functionalized ZnO NPs < 0.5 mm. This corresponds with leaching, 25.9% of unmodified ZnO NPs leached from membrane compared with 5.8% for the covalently-bonded ZnO NPs.

Ultrahigh uranium extraction performance of COFs/SPES mixed matrix membranes at acidic medium

Extracting uranium from strongly acidic uranium-containing wastewater by a gentle and efficient method is a globally challenge problem. In this paper, sulfonated-polyethersulfone (SPES) membranes and [NH4]+[COF–SO3-]/SPES mixed matrix membranes (MMMs) were synthesized and for the first time investigated for the extraction of uranium from acidic uranium aqueous solutions of pH ​= ​1, filling the void of SPES-based membranes in the application in uranium absorption. The static adsorption thermodynamics of SPES membranes and [NH4]+[COF–SO3-]/SPES MMMs towards uranium were investigated, and the adsorption mechanism was studied through the measurement of SEM, FT-IR, XPS and EDX. The results displayed that, SPES membranes demonstrated outstanding adsorption capacity of 42.1 ​mg g−1and [NH4]+[COF–SO3-]/SPES MMMs showed the record-breaking adsorption capacity of 99.4 ​mg ​g−1 at pH ​= ​1, resulting from the synergistic adsorption effect of [NH4]+[COF–SO3-] and SPES. Moreover, the kinetics, dynamic adsorption/desorption and membrane reusability of [NH4]+[COF–SO3-]/SPES MMMs were investigated. It was found that, the [NH4]+[COF–SO3-]/SPES MMMs exhibited high removal rate of 99%, and excellent reusability even after five recycles, demonstrating great potential in the recovery of uranium from uranium mine water.

Ultra-fine electrospun nanofibrous membranes for multicomponent wastewater treatment: Filtration and adsorption

Electrospun sulfonated polyethersulfone (SPES) nanofibrous membranes with ultra-fine mean fiber diameter, e.g., 62 ± 16 nm, were fabricated by a two-nozzle electrospinning approach and employed as a multi-functional membrane for removal of nanoparticles, dyes, and heavy metal ions from multicomponent wastewater through filtration and adsorption, simultaneously. The pore size and pore size distribution of the membrane could be varied and adjusted by controlling the fiber diameter, which affects the filtration retention of nanoparticles while the sulfonic groups located on the surface of the nanofibers work as active sites for the adsorption of dyes and heavy metal ions by electrostatic interaction. Increase in the degree of sulfonation and decrease in the concentration of solution led to the reduction of fiber diameter of the electrospun nanofibrous membranes, as evidenced by SEM and TEM measurements, in addition to the increase in the molecular weight of SPES. The adsorption kinetics and thermodynamics of the nanofibrous membrane for cationic dye and heavy metal ions were investigated, separately, in addition to the filtration performance of nanoparticle suspensions. The ultra-fine nanofibrous SPES membrane was finally tested, with simulated multicomponent wastewater containing 0.2 μm-particles, methylene blue (MB), and Pb (II) ions. The membrane exhibited high permeation flux of 320 L/m2h, high retention of >99.0% against nanoparticles, MB and Pb (II), as well as high treated capacity in the filtration performance. The nanofibrous SPES membranes after adsorption of MB and Pb (II) were able to be recovered which indicated the sustainable nature of the membrane for real wastewater treatment.

Protonated state and synergistic role of Nd3+ doped barium cerate perovskite for the enhancement of ionic pathways in novel sulfonated polyethersulfone for H2/O2 fuel cells.

In recent decades, there has been a need for novel advancement of sustainable non-fluorinated polymer electrolyte membranes for proton exchange membrane fuel cell (PEMFC) applications. The set forth strategy aims to ameliorate proton conduction of sulfonated polyethersulfone (SPES) polymer membranes with a distinct mixture of barium cerate (BCO) and neodymium-doped barium cerate (BCNO) perovskites developing cationic composite membranes (CCMs) prepared through a technique of solvent casting. The CCMs were subjected to analysis of their mechanical, structural, chemical compositional, thermal, morphological, oxidative, physicochemical, electrochemical and fuel cell polarization performance respectively. Acceptor doping of the trivalent neodymium group at the B site of BCO increases the number of oxygen vacancies and improves ionic conduction. The CCM of neodymium-doped barium cerate demonstrates a higher proton conductivity of 42.2 mS cm-1 with a lower activation energy of 6.80 kJ mol-1 at 80 °C. The maximum current density and power density with the OCV of 0.93 V for the neodymium-doped barium cerate membrane are 397 mA cm-2 and 117 mW cm-2, which is 1.8 times greater than that of the pure SPES membrane. On the basis of polarization performance, the SPES membrane with neodymium-doped barium cerate has great potential in highly-efficient PEMFC applications.

Effect of functionalized silica nanoparticles on sulfonated polyethersulfone ion exchange membrane for removal of lead and cadmium ions from aqueous solutions

Polyethersulfone (PES) was successfully sulfonated by sulfuric acid and used for membrane synthesis. Silica nanoparticles were functionalized by amine and thiol groups and then introduced in a sulfonated polyethersulfone membrane (SPES) matrix. The effect of silica and functionalized silica particles on ion exchange of lead ion (Pb2+) and cadmium ion (Cd2+) was studied. X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy-Energy dispersive X-ray spectroscopy (SEM-EDX) analysis were used to confirm the successful functionalization of silica particles and the effective incorporation of silica and the functionalized silica particles in the membranes matrix. The dialysis process during 8 h,using the SPES-SiO2-(CH2)3-NH2 membrane, leads to a significant elimination rate of Pb2+and Cd2+ ions estimated at 43.2% and 31.6%, respectively. whereas a selective separation of Pb2+ from feed (Pb2+/Cd2+) solution was observed at 2 h of dialysis. On the other hand, the SPES-SiO2-(CH2)3-SH membrane adsorbs more Cd2+ than Pb2+ ions, which represents another outcome for Pb2+/ Cd2+ separation.

The synthesis of sulfonated polyethersulfone (SPES) and the preparation of its membranes as matrix in the immobilization of Candida antarctica lipase B (Cal-B)

The immobilization of lipases is often used in biotechnology to improve the performance, reusability, and stability of the enzyme. Candida antarctica lipase B (Cal-B) has been used as a catalyst in trans-esterification reaction. To improve the utilization of Cal-B, therefore the immobilization of Cal-B onto a polymer matrix became crucial. In this study, polyethersulfone (PES) and sulfonated polyethersulfone (SPES) membranes were used as matrices of Cal-B immobilization. SPES was previously synthesized by modifying PES using chlorosulfonic acid (ClSO3H) to improve the immobilization of Cal-B. SPES-PSf (polysulfone) blended membranes were also successfully prepared by blending SPES, PSf, and PEG in N-methylpyrrolidone (NMP) as the solvent using phase-inversion method. The attenuated total reflectance (ATR)–FTIR spectrum showed characteristic peaks of the immobilized Cal-B on the matrix at peak 3184.03 cm−1 (–N–H bonds) and 1683.49 cm−1 (–CH deformation bonds). The Raman spectroscopy of the PES-based membranes before and after sulfonation reaction showed the deviations from the symmetrical structure of PES, with specific Raman shifts at 784.11 cm−1, 1150.95 cm−1, and 1588.9 cm−1. Cal-B was successfully immobilized and loaded onto SPES membrane. By Lowry assay, it was detected that 140.3 μg/cm2 enzyme was successfully loaded into the 17.3 cm2 of membrane. The value was one and a half times higher than PES (91.0 μg/cm2 in 17.3 cm2). However, the hydrolytic activity of Cal-B immobilized onto SPES membrane (17.0 p-NP/min/cm2) was five times lower than Cal-B immobilized onto PES membrane (80.4 p-NP/min/cm2).

Surface modification of sulfonated polyethersulfone membrane with polyaniline nanoparticles for application in direct methanol fuel cell

A novel polyion nanocomposite membrane was synthesized by doping the surface and matrix of sulfonated polyethersulfone (SPES) with polyaniline (PANi) nanoparticles to facilitate proton conduction in direct methanol fuel cell (DMFC) application. The synthesized membrane exhibited effective, ionic interaction, dense morphology with high thermal stability, adequate tensile strength (60 Mpa) and considerable ion exchange capacity (2.2 meq g−1). The membrane exhibited low methanol permeability of 7.46 × 10−8 cm2s−1 with high proton conductivity (0.098 Scm−1) besides adequate hydrolytic and oxidative stabilities. A maximum power density of 99 mWcm−2 at a current density of 250 mAcm−2 was obtained with a single slice fuel cell setup. Molecular dynamics simulation based on the COMPASS force-field was applied to investigate the influence of PANi nanoparticles, temperature and hydration level on the diffusivity of hydronium ions. Rapid mass transfer of hydronium ions within the PANi incorporated SPES membrane, could be achieved at higher temperatures and hydration levels. Analysis by radial distribution function (RDF) revealed extensive interactions of sulfonic acid groups of SPES and amine groups of PANi with water molecules. The polyion complex membrane was found to exhibit significant prospect of scale-up for potential application in DMFC.