Structural Characterization and Physicochemical Properties of Functionally Porous Proton-Exchange Membrane Based on PVDF-SPA Graft Copolymers.

Fluorinated proton-exchange membranes (PEMs) based on graft copolymers of dehydrofluorinated polyvinylidene fluoride (D-PVDF), 3-sulfopropyl acrylate (SPA), and 1H, 1H, 2H-perfluoro-1-hexene (PFH) were prepared via free radical copolymerization and characterized for fuel cell application. The membrane morphology and physical properties were studied via small-(SAXS) and wide-angle X-ray scattering (WAXS), SEM, and DSC. It was found that the crystallinity degree is 17% for PEM-RCF (co-polymer with SPA) and 16% for PEM-RCF-2 (copolymer with SPA and PFH). The designed membranes possess crystallite grains of 5-6 nm in diameter. SEM images reveal a structure with open pores on the surface of diameters from 20 to 140 nm. Their transport and electrochemical characterization shows that the lowest membrane area resistance (0.9 Ωcm2) is comparable to perfluorosulfonic acid PEMs (such as Nafion®) and polyvinylidene fluoride (PVDF) based CJMC cation-exchange membranes (ChemJoy Polymer Materials, China). Key transport and physicochemical properties of new and commercial membranes were compared. The PEM-RCF permeability to NaCl diffusion is rather high, which is due to a relatively low concentration of fixed sulfonate groups. Voltammetry confers that the electrochemical behavior of new PEM correlates to that of commercial cation-exchange membranes, while the ionic conductivity reveals an impact of the extended pores, as in track-etched membranes.

Analysis of Dielectric Parameters of Fe2O3-Doped Polyvinylidene Fluoride/Poly(methyl methacrylate) Blend Composites.

In this paper, we report the effect of metal oxide (Fe2O3) loading in different weight ratios (0.5%, 1%, 2%, and 4%) on the structural and electrical parameters, viz., the complex dielectric constant, electric modulus spectra, and the AC conductivity, of polymeric composites of PVDF/PMMA (30/70 weight ratio) blend. The structural and geometric measurements have been analyzed with the help of peak location, peak intensity, and peak shape obtained from XRD as well as from FTIR spectra. The electrical properties have been investigated using an impedance analyzer in the frequency range 100 Hz to 1 MHz. The real parts of the complex permittivity and the dielectric loss tangent of these materials are found to be frequency independent in the range from 20 KHz to 1 MHz, but they increase with the increase in the concentration of nano-Fe2O3. The conductivity also increases with an increased loading of Fe2O3 in PVDF/PMMA polymer blends. The electric modulus spectra were used to analyze the relaxation processes associated with the Maxwell-Wagner-Sillars mechanism and chain segmental motion in the polymer mix.

Effective management of passive layers using composite cathodes in solid state magnesium batteries.

A simple and effective method for the management of the passive layer in solid state batteries is reported. The success is achieved using a composite cathode with embedded channels of polyaniline allowing smooth charge transfer across the passive layer. The composite cathode manifested better performance in terms of the cell characteristics and shelf life.

Multivariate modeling and process optimization of Hg(II) remediation using solvothermal synthesized 2D MX/Fe3O4 by response surface methodology: characteristics and mechanism study.

Two-dimensional MXene with layered structure has recently emerged as a nanomaterial with fascinating characteristics and applicability. Herein, we prepared the newly modified magnetic MXene (MX/Fe3O4) nanocomposite using solvothermal approach and investigated its adsorption behavior to study the removal efficiency of Hg(II) ions from aqueous solution. The effect of adsorption parameters such as adsorbent dose, time, concentration, and pH were optimized using response surface methodology (RSM). The experimental data fitted well with quadratic model to predict the optimum conditions for maximum Hg(II) ion removal efficiency which were found to be at adsorbent dose 0.871 g/L, time 103.6 min, concentration 40.17 mg/L, and 6.5 pH respectively. To determine the adequacy of the developed model, a statistical analysis of variance (ANOVA) was used, which demonstrated high agreement between the experimental data and the suggested model. According to isotherm result, the experimental data were following the best agreement with the Redlich-Peterson isotherm model. The results of the experiments revealed that the maximum Langmuir adsorption capacity of 699.3 mg/g was obtained at optimum conditions, which was closed to the experimental adsorption capacity of 703.57 mg/g. The adsorption phenomena was well represented by the pseudo-second-order model (R2 = 0.9983). On the whole, it was clear that MX/Fe3O4 has lot of potential as a Hg(II) ion impurity removal agent in aqueous solutions.

Sulfonated Poly(2,6-dimethyl-1,4-phenylene ether)-Modified Mixed-Matrix Bifunctional Polyelectrolyte Membranes for Long-Run Anthrarufin-Based Redox Flow Batteries.

The resurgence in designing polyelectrolyte membrane (PEM) materials has propound grid-scale electrochemical energy storage devices. Herein, we report on studies corroborating the synergistic influence of ionic domain microstructure modification and intercalation of telechelic bis-piperidinium-functionalized graphene oxide (GO) to fabricate stable bifunctional membranes from sulfonated poly(2,6-dimethyl-1,4-phenylene ether) (sPPE) for efficient anthrarufin-based alkaline redox flow batteries. A critically long-lasting quest on alkaline stability and -OH conductivity dilemma in hydrocarbon-based PEMs is meticulously resolved via a bifunctional ion-conducting matrix. Preferential studies on hydrophilic domain distribution in sPPE suggest that, with high microphase homogeneity, higher specific capacity retentions are achievable during galvanostatic charge-discharge (GCD) analysis. Moreover, the low-capacity issues were overcome by improving the redoxolyte-membrane interface affinities incorporating bis-piperidinium-bearing graphene oxide (bis-QGO). Consequently, at 1.0 and 2.0 wt % intercalation of bis-QGO, the bifunctional polyelectrolyte membranes (BFPMs) impart lowest overpotentials of 93 mV (for BFPM-1.0) and ∼100 mV (for BFPM-2.0) which are ∼43 and 40% lower than that of Nafion-117 (i.e., ∼164 mV). Furthermore, the efficiency of BFPMs, viz., the Coulombic, voltage, and energy efficiencies, was ∼95-98%, ∼85%, and ≥80% at 20 mA cm-2, respectively. In long-cycling operations, the GCD profile evidenced ∼99% efficiency retention over 450 cycles and illustrated reproducible rate capability. Finally, the polarization studies of BFPMs revealed ∼54% higher peak power density (87.5 mW cm-2) delivery than Nafion-117 (∼57 mW cm-2). We believe that this strategic designing approach could offer newer and simple avenues to avail high-performance BFPMs at low intercalation loads for alkaline electrochemical energy storage and related applications.

Sulphonated poly(ethersulfone)/carbon nano-onions-based nanocomposite membranes with high ion-conducting channels for salt removal via electrodialysis.

Herein, we are reporting the carbon nano onions (CNO)-based sulphonated poly(ethersulfone) (SPES) composite membranes by varying CNO content in SPES matrix for water desalination applications. CNOs were cost-effectively synthesized using flaxseed oil as a carbon source in an energy efficient flame pyrolysis process. The physico- and electrochemical properties of nanocomposite membranes were evaluated and compared to pristine SPES. Moreover, the chemical characterisation of composite membranes and CNOs were illustrated using techniques such as nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (FE-SEM), thermogravimetric analysis (TGA) and universal tensile machine (UTM). In the series of nanocomposite membranes, SPES-0.25 composite membrane displayed the highest water uptake (WU), ion exchange membrane (IEC) and ionic conductivity (IC) values that were enhanced by 9.25%, ~ 44.78% and ~ 6.10%, respectively, compared to pristine SPES membrane. The electrodialytic performance can be achieved maximum when membranes possess low power consumption (PC) and high energy efficiency (Ee). Therefore, the value of Ee and Pc for SPES-0.25 membrane has been determined to be 99.01 ± 0.97% and 0.92 ± 0.01 kWh kg-1, which are 1.12 and 1.11 times higher than the pristine SPES membrane. Hence, integrating CNO nanoparticles into the SPES matrix enhanced the ion-conducting channels.

Dengue outbreak and severity prediction: current methods and the future scope.

Dengue virus (DENV) is the causative agent of dengue fever and severe dengue. Every year, millions of people are infected with this virus. There is no vaccine available for this disease. Dengue virus is present in four serologically varying strains, DENV 1, 2, 3, and 4, and each of these serotypes is further classified into various genotypes based on the geographic distribution and genetic variance. Mosquitoes play the role of vectors for this disease. Tropical countries and some temperate parts of the world witness outbreaks of dengue mainly during the monsoon (rainy) seasons. Several algorithms have been developed to predict the occurrence and prognosis of dengue disease. These algorithms are mainly based on epidemiological data, climate factors, and online search patterns in the infected area. Most of these algorithms are based on either machine learning or deep learning techniques. We summarize the different software tools available for predicting the outbreaks of dengue based on the aforementioned factors, briefly outline the methodology used in these algorithms, and provide a comprehensive list of programs available for the same in this article.

Green-synthesized, pH-stable and biocompatible carbon nanosensor for Fe3+: An experimental and computational study.

Brightly fluorescent Carbon Dots (CDs) were synthesized by green hydrothermal method using commonly available biomass (Aloe vera) as carbon precursor. Their physiochemical and optical characterization was done by standard microscopic and spectroscopic techniques. Photophysical features of their aqueous dispersion were investigated in detail. The influence of wide pH range (2-12), high ionic load (2M) and temperature on their photoluminescence behavior was investigated. Their in-vitro cytotoxicity examination was conducted on Human Cervical Cancer Cells (HeLa) using MTT assay. Testing of their ion-recognition property for common metal ions was done in aqueous medium. These CDs exhibited preferential interaction with Fe3+ over other tested metal ions, without any functionalization. Interaction between CDs and Fe3+ was analyzed in the light of Density Functional Theory (DFT). The work demonstrates that these CDs are acting as nanoprobe for Fe3+ and sensing it at ultra-trace level (5 nM).

Synthesis of highly fluorescent and water soluble graphene quantum dots for detection of heavy metal ions in aqueous media.

Fluorescent graphene quantum dots (GQDs) are nanomaterials which possess unique properties that show great potential in different applications. In this work, GQDs were synthesized using graphene oxide (GO) as precursor via thermal treatment at high temperature. The obtained GQDs were highly fluorescent and were suitable for the determination of heavy metal ions. X-ray diffraction, FTIR spectroscopy, and UV visible spectroscopy confirm the formation of GQDs. TEM images show that formed GQDs have size ranging from 2 to 10 nm. Emission profile of aqueous GQDs was taken by exciting GQDs at different wavelength. The intensity of GQDs remains the same for 4-5 months. Furthermore, as prepared, GQDs were used for selective recognition of Fe3+, Pb+2, and Cr3+ from the bunch of different metal ions in aqueous media. Lower limit of detection obtained for Fe3+, Cr3+ and Pb2+ using GQDs were 50, 100 and 100 nM, respectively, which indicates that the GQDs can be utilized as a promising material for sensing of the heavy metal ions. Graphical abstract.

An Investigation of a (Vinylbenzyl) Trimethylammonium and N-Vinylimidazole-Substituted Poly (Vinylidene Fluoride-Co-Hexafluoropropylene) Copolymer as an Anion-Exchange Membrane in a Lignin-Oxidising Electrolyser.

Electrolysis is seen as a promising route for the production of hydrogen from water, as part of a move to a wider "hydrogen economy". The electro-oxidation of renewable feedstocks offers an alternative anode couple to the (high-overpotential) electrochemical oxygen evolution reaction for developing low-voltage electrolysers. Meanwhile, the exploration of new membrane materials is also important in order to try and reduce the capital costs of electrolysers. In this work, we synthesise and characterise a previously unreported anion-exchange membrane consisting of a fluorinated polymer backbone grafted with imidazole and trimethylammonium units as the ion-conducting moieties. We then investigate the use of this membrane in a lignin-oxidising electrolyser. The new membrane performs comparably to a commercially-available anion-exchange membrane (Fumapem) for this purpose over short timescales (delivering current densities of 4.4 mA cm-2 for lignin oxidation at a cell potential of 1.2 V at 70 °C during linear sweep voltammetry), but membrane durability was found to be a significant issue over extended testing durations. This work therefore suggests that membranes of the sort described herein might be usefully employed for lignin electrolysis applications if their robustness can be improved.

Boron nitride: a promising material for proton exchange membranes for energy applications.

Boron nitride (BN) is an exciting material and has drawn the attention of researchers for the last decade due to its surprising properties, including large surface area, thermomechanical stability, and high chemical resistance. Functionalization of BN is a new area of interest to build up novel properties and applications of BN. BN and functionalized BN are promising membrane materials and show enormous advantages ascribed to their simple synthesis, high surface area, mechanical and thermal stability, and distinctive mechanical properties. BN-based proton exchange membranes show improvement in their physicochemical, electrochemical, thermal, mechanical, and barrier properties. Only a few research studies have been carried out on BN-based highly stable proton exchange membranes (PEMs) for various electrochemical applications. In this review, we discuss the recent advances in the functionalization of BN by different methods. The synthesis of different proton exchange membranes has also been discussed in this article. In addition, the potential applications of hybrid proton exchange membranes have also been mentioned.

Synthesis of Chloride-Free Potash Fertilized by Ionic Metathesis Using Four-Compartment Electrodialysis Salt Engineering.

A sustainable approach for the production of high-purity potash fertilizers devoid of chloride is highly needed. Conventional preparation processes for chloride-free potash fertilizers have certain limitations, such as complicated synthesis procedure, including high-temperature requirement, causing environmental pollution. In this work, a novel approach has been proposed for the production of high-purity potash fertilizer (KNO3, K2SO4, and KH2PO4) from KCl by metathesis electrodialysis (MED). Sulfonated poly(ether sulfone)-based cation-exchange membrane and quaternized brominated poly(2,6-dimethyl-1,4-phenylene oxide)-based anion-exchange membranes are used for the MED experiments. The membranes show adequate water uptake, ionic conductivity, and ion-exchange capacity with good mechanical and thermal stabilities. The yields of KNO3, K2SO4, and KH2PO4 are found to be 90, 86, and 90%, respectively. The power consumptions during MED experiment for KNO3, K2SO4, and KH2PO4 are calculated to 0.94, 0.89, and 1.04 kWh/kg, respectively. The purity of products is confirmed by inductively coupled plasma and X-ray diffraction analysis and by measuring ionic contents. The process provides an energy-intensive way for high-purity synthesis of KNO3, K2SO4, and KH2PO4.

Single-Step Synthesis of Magnesium-Doped Lithium Manganese Oxide Nanosorbent and Their Polymer Composite Beads for Selective Heavy Metal Removal.

Magnesium-doped lithium manganese oxide nanosorbent is prepared by a single-step solid-state method and characterized with appropriate analytical techniques, adsorption kinetic model, and isotherms. Competitive and noncompetitive adsorption studies are performed for a range of heavy metal ions. Prepared nanosorbent has shown explicit selectivity for various heavy metal ions and no remarkable influence of coexisting common interfering ions (Na+, K+, Mg2+, and Ca2+), which generally coexist with all natural sources of water, contaminated water, and industrial waste. To achieve easy handling of an adsorbent, polysulfone-nanosorbent (PS-nanosorbent) composite beads are prepared, and their competitive heavy metal removal performance is determined. Competitive adsorption and regeneration studies have shown that PS-nanosorbent beads can be employed for selective heavy metal removal and reuse for multiple cycles.

Semi-Interpenetrating Network-Type Cross-Linked Amphoteric Ion-Exchange Membrane Based on Styrene Sulfonate and Vinyl Benzyl Chloride for Vanadium Redox Flow Battery.

Clean energy is the main requirement for human life. Redox flow battery may be an alternative to fossil fuels. An ion-exchange membrane is the heart of the redox flow battery. In the present study, we synthesize semi-interpenetrating cross-linked copolymer amphoteric ion-exchange membranes (AIEMs) with a partially rigid backbone. The styrene sulfonate and vinyl benzyl chloride monomers are used as the cationic and anionic moieties into the AIEMs. Three different types of quaternizing agents are used to convert a primary amine into a quaternary amine group. Here, we avoid the use of the carcinogenic chemical CMME, commonly used for the synthesis of anion-exchange membranes. The prepared membranes exhibit good electrochemical and physicochemical properties with a high acidic stability. The membranes also show moderate water uptake and dimensional change. The ZWMO membrane shows better properties among the AIEMs, with an ionic conductivity of 3.12 × 10-2 S cm-1 and 5.49 water molecules per functional group. The anion and cation-exchange capacities of the ZWMO membranes are calculated to be 1.11 and 0.62 mequiv/g. All AIEMs show good thermal and mechanical stabilities, calculated by differential scanning calorimetry, dynamic mechanical analysis, and universal testing machine analysis. The membranes show low vanadium ion permeability than the commercial membrane Nafion for their use in vanadium redox flow batteries. Further, the AIEMs are applied in redox flow batteries as separators and deliver good results with the charging and discharging phenomena, with 87% voltage efficiency and 91% current efficiency.

Characterization of asymmetric polymeric membranes by gas permeation.

Polycarbonate films (thickness 18, 25 and 38 microm) were irradiated by a beam of 100MeV Ni7+ ion. The permeability for hydrogen and carbon dioxide was measured from both sides of membrane at increasing etching time. These membranes show larger permeability from the irradiation side, than the reverse side indicating the formation of conical tracks and asymmetrical membrane. The stopping range (Se) of 100MeV Ni7+ ion beam in polycarbonate is 22microm, for 18microm thick membrane the etching time at which the permeability increases rapidly is less than that of 38microm thick membrane, for both the gases. The difference in permeability from the two sides is attributed to the conical shape of the track generated by the ions. The controlled flow rate of the membrane leads to the design of a special type of gas filter.

Enhanced Electrochemical Performance of Stable SPES/SPANI Composite Polymer Electrolyte Membranes by Enriched Ionic Nanochannels.

Herein, we present the results of sulfonated polyaniline (SPANI) and sulfonated poly(ether sulfone) (SPES) composite polymer electrolyte membranes. The membranes are established for high-temperature proton conductivity and methanol permeability to render their applicability. Composite membranes have been prepared by modifying the SPES matrix with different concentrations of SPANI (e.g., 1, 2, 5, 10, and 20 wt %). Structural and thermomechanical characterizations have been performed using the transmission electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analyzer techniques. Physicochemical and electrochemical properties have been evaluated by water uptake, ion-exchange capacity, dimensional stability, and proton conductivity. Methanol permeability experiment was carried out to analyze the compatibility of prepared membranes toward direct methanol fuel cell application and found the lowest methanol permeability for PAS-5. Also, the membranes reveal excellent thermal, mechanical, and physicochemical properties for their application toward high-temperature electromembrane processes.

Dramatic improvement in water retention and proton conductivity in electrically aligned functionalized CNT/SPEEK nanohybrid PEM.

Nanohybrid membranes of electrically aligned functionalized carbon nanotube f CNT with sulfonated poly ether ether ketone (SPEEK) have been successfully prepared by solution casting. Functionalization of CNTs was done through a carboxylation and sulfonation route. Further, a constant electric field (500 V·cm(-2)) has been applied to align CNTs in the same direction during the membrane drying process. All the membranes are characterized chemically, thermally, and mechanically by the means of FTIR, DSC, DMA, UTM, SEM, TEM, and AFM techniques. Intermolecular interactions between the components in hybrid membranes are established by FTIR. Physicochemical measurements were done to analyze membrane stability. Membranes are evaluated for proton conductivity (30-90 °C) and methanol crossover resistance to reveal their potential for direct methanol fuel cell application. Incorporation of f CNT reasonably increases the ion-exchange capacity, water retention, and proton conductivity while it reduces the methanol permeability. The maximum proton conductivity has been found in the S-sCNT-5 nanohybrid PEM with higher methanol crossover resistance. The prepared membranes can be also used for electrode material for fuel cells and batteries.

SGO/SPES-based highly conducting polymer electrolyte membranes for fuel cell application.

Proton-exchange membranes (PEMs) consisting of sulfonated poly(ether sulfone) (SPES) with enhanced electrochemical properties have been successfully prepared by incorporating different amount of sulfonated graphene oxide (SGO). Composite membranes are tested for proton conductivity (30-90 °C) and methanol crossover resistance to expose their potential for direct methanol fuel cell (DMFC) application. Incorporation of SGO considerably increases the ion-exchange capacity (IEC), water retention and proton conductivity and reduces the methanol permeability. Membranes have been characterized by FTIR, XRD, DSC, SEM, TEM, and AFM techniques. Intermolecular interactions between the components in composite membranes are established by FTIR. The distribution of SGO throughout the membrane matrix has been examined using SEM and TEM and found to be uniform. The maximum proton conductivity has been found in 5% SGO composite with higher methanol crossover resistance.

Cross-linked hybrid nanofiltration membrane with antibiofouling properties and self-assembled layered morphology.

A new siloxane monomer, 3-(3-(diethoxy(2-(5-(4-(10-ethoxy-4-hydroxy-2,2-dimethyl-11-oxa-2-ammonio-6-aza-10-silatridecan-10-yl)phenyl)-1,3,4-oxadi azol-2-ylthio)ethyl)silyl)propylamino)-2-hydroxy-N,N,N-trimethylpropan-1-aminium chloride (OA), was synthesized by reported 3-((4-(5-(2-((3-aminopropyl) diethoxysilyl)ethylthio)-1,3,4-oxadiazol-2-yl)phenyl) diethoxysilyl)propan-1-amine (APDSMO) and glycidyltrimethylammonium chloride (GDTMAC) by epoxide ring-opening reaction. OA-poly(vinyl alcohol) (PVA) hybrid antibiofouling nanofilter (NF) membranes were prepared by acid-catalyzed sol-gel followed by formal cross-linking. Membranes showed wormlike arrangement and self-assembled layered morphology with varying OA content. Hybrid NF membrane, especially OA-6, showed low surface roughness, high hydrophilic nature, low biofouling, high cross-linking density, thermal and mechanical stablility, solvent- and chlorine-tolerant nature, along with good permeability and salt rejection. Prepared OA-6 hybrid NF membrane can be used efficiently for desalting and purification of water with about 2.0 g/L salt content (groundwater in major part of India). The described method provides novel route for producing antibiofouling membranes of diversified applications.

Change in the microstructure at W/Si interface and surface by swift heavy ions.

Metal/Si thin film interfaces and surfaces can be modified by swift heavy ions (SHI) in a controlled manner. The mixing induced by 120 MeV Au(+9) ions at W/Si interface are presented in the manuscript. Grazing Incident X-ray Diffraction (GIXRD) result shows the formation of two type of tungsten silicides t-W(5)Si(3) along with t-WSi(2) by atomic mixing at the interface on increasing the ion fluence. The diffusivity value calculated from the Rutherford Backscattering Spectroscopy (RBS) measurements, suggest a transient molten phase at the interface causing the atomic mixing following by Thermal spike model. Atomic Force Microscopy (AFM) results revealed increase in surface roughness and grain size formation, which increases with ion fluence showing the irradiation effect at the surface also.