Sulfonated Poly Vinylidene Fluoride Research Articles

Alkaline electrolysis of wastewater and low-quality water

Green hydrogen production by water electrolysis is an inevitable solution for global sustainability. However, for making hydrogen energy as next-generation fuel, enough pure water and associated cost is required, which is another critical issue that must be resolved. An attempt has been made to produce hydrogen gas from low-grade and wastewater using alkaline water splitting. The electrodes, electrolyte, voltage, and impurity level have significantly affected hydrogen generation. Turbidity and total dissolved solids have been found to be important factors whose removal can enhance hydrogen production from wastewater. A high-strength sulfonated polyvinylidene fluoride (HSPVDF) ultrafiltration (UF) membrane was used to produce high-quality advanced treated water. Tertiary UF membrane treatment has contributed substantially to residual impurity removal and improved hydrogen generation. The study suggests that wastewater and advanced treated watercan effectively utilize green hydrogen generation with impurity removal. Based on this finding, the potential applicability for achieving energy independence in municipal wastewater treatment plants was examined. Replacing water with wastewater can be a new dimension of the hydrogen economy.

Fabrication and application of novel high strength sulfonated PVDF ultrafiltration membrane for production of reclamation water

Advanced treated water (ATW) produced in wastewater treatment facilities was assessed as an excellent alternative water resource that can be used as reclamation water, such as indirect and direct potable reuse. The development of cutting-edge technology for simple but best practices is essential for the reliable production of safe reclamation water from wastewater. This study prepared a novel high strength sulfonated polyvinylidene fluoride (HSPVDF) ultrafiltration membrane and investigated to produce ATW, and performances were compared to sulfonated PVDF (SPVDF) (which was prepared without thermal treatment) and bare PVDF. To compare the properties of HSPVDF to hydrocarbon polymer, the polyetherimide (PEI) and Sulfonated PEI (SPEI) membrane were prepared. HSPVDF showed excellent membrane morphology, porosity, MWCO, and hydrophilicity, resulting in higher pure water flux (712 ± 6 L m−2 h−1) antifouling properties (Rir 1.3% and FRR 98.6%) compared to PVDF. It is an interesting fact that the tensile strength of the HSPVDF (3.4 ± 0.2 MPa) tremendously increased (3 folders) when compere to PVDF (1.3 ± 0.1 MPa). The HSPVDF membrane showed good removal efficiency up to 96 ± 05% and 97 ± 09% rejection for bovine serum albumin (BSA) and humic acid (HA), respectively. The membrane application studies for wastewater treatment showed that the tertiary HSPVDF UF membrane filtration following the nutrient removal activated sludge (NRAS) process can produce reliable and economic performance (125 ± 2 L m−2 h−1, 0.25 ± 0.05 NTU, no pathogens), suggesting that it can be a best practice technique that can replace the complicated multi-staged tertiary processes to produce reclamation water.

Sulfonated polyvinylidene fluoride-crosslinked-aniline-2-sulfonic acid as ion exchange membrane in single-chambered microbial fuel cell

A novel interpenetrating polymeric network (IPN) of sulfonated polyvinylidene fluoride (SPVDF), nano-alumina (Al2O3), and aniline-2-sulfonic (A2S) acid with crosslinker divinylbenzene (DVB) is employed as an ion-exchange membrane in single-chambered microbial fuel cells (MFCs). Results reveal that the increasing concentration of A2S (10, 20, and 30 wt%) enhances the relative hydrophilicity and other intrinsic properties of the membranes. A series of characterizations like water uptake, swelling ratio, ion-exchange, proton conductivity, and tensile testing, affirms the enhanced attributes of the casted membranes. The increasing concentration of crosslinker DVB (> 1.4 wt%) constricts the internal spacing of the membrane that, in turn, hinders the transverse ionic conduction within the highly crosslinked, AS30 membrane. A maximum power and current density of 450.36 ± 23mW m-2 and 1734 ± 87mA m-2 was found in AS20 fitted MFC with around 89% of chemical oxygen demand (COD) removal in 30 days of operation. Incorporation of A2S and Al2O3 in SPVDF moiety demonstrates an approximate increment of 36% and 7% higher MFC performance over n-SPVDF and highly crosslinked AS30 membrane. The relative effect of these novel IPN membranes has been highlighted here as cost-efficient separator in MFCs for green electricity production, employing mixed firmicutes as biocatalyst.

Sulfonated polyvinylidene fluoride and functional copolymer based blend proton exchange membrane for fuel cell application and studies on methanol crossover

Copolymers of poly(methyl methacrylate)-co-poly (2-acrylamido-2-methyl-1-propane sulfonic acid (PMMA-co-PAMPS) have been prepared via radical polymerization with different MMA to AMPS mol ratio and blended with polyvinylidene fluoride (PVDF) and sulfonated PVDF (S-PVDF) in a different weight ratio to prepare proton exchange membranes (PEMs) by simple solution casting method for fuel cells application (PEMFCs). Five different PEMs have been prepared from only PMMA-co-PAMPS, blending PMMA-co-PAMPS with PVDF, and also by blending PMMA-co-PAMPS with S-PVDF to get the suitable membrane for PEMFCs application. We have also studied the effect of PVDF and S-PVDF in the blend membranes on the water uptake, mechanical stability, thermal stability, proton conductivity (Km), and methanol permeability (PM) properties. PEMs prepared by blending with S-PVDF exhibited high Km and low PM value. PEM-5 membrane prepared by blending S-PVDF with PMMA-co-PAMPS (30:70 w/w) exhibited Km at room temperature 5.7 × 10−2 S/cm, PM value 5.24 × 10−7 cm2/s and maximum power density 477 mW/cm2. This PM value is much lower than that of the Nafion® 117 membrane (22 × 10−7 cm2/s). This low PM, high Km and high selectivity make the S-PVDF blend membranes a good candidate in PEMFCs or direct methanol fuel cells (DMFCs) application.

Effect of Bromine Complexing Agents on Membrane Performance in Hydrogen Bromine Flow Batteries

The addition of bromine complexing agent (BCA) to bromine electrolyte is an accepted method to reduce bromine vapor pressure making bromine-based flow batteries inherently safer. It is well-known that the amine functional group of the BCAs interact with Nafion membranes. The novelty of the current work is that it investigates how this interaction of BCA with the four different membrane chemistries impacts the membrane characteristics and performance of hydrogen bromine flow batteries (HBFBs). The impact of BCA 13 on the system performance is determined by the membrane chemistry. Exposure of Nafion membranes to BCA leads to 60% higher cell resistance, and 55% lower cell power density at 0.5 V at 50% state-of-charge (SOC). This decrease is caused by the strong interaction between the negatively charged sulfonic acid groups in the membrane and the positively charged BCA. Lower SOC, lower bromine concentration and a higher free BCA concentration is detrimental in the cell operation. The use of LC PFSA membranes in the presence of BCA ions should be avoided. while BCA in combination with grafted sulfonated polyvinylidene fluoride (SPVDF) or grafted sulfonated polyethylene (SPE) membranes promising HBFB results are obtained.

Chitosan/partially sulfonated poly(vinylidene fluoride) blends as polymer electrolyte membranes for direct methanol fuel cell applications

A novel proton exchange membranes composed of a blend of chitosan and sulfonated polyvinylidene fluoride (SPVDF) was prepared by solution casting technique. The PVDF was sulfonated using direct sulfonation method with sulfonation degree of 6.1%. The membranes with different fractions of SPVDF were prepared and 10 wt% SPVDF exhibits the best performance in terms of ion exchange capacity, conductivity, water uptake and membrane selectivity. The prepared blend membranes show excellent combination of thermal stability, mechanical properties, dimensional stability and methanol barrier properties. Chitosan (CS)-SPVDF-90/10 membrane shows the highest proton conductivity of 2.85 × 10−2 S cm−1 at 90 °C.

Investigation of antifouling performance a novel nanofibrous S-PVDF/PVDF and S-PVDF/PVDF/GO membranes against negatively charged oily foulants

Novel electrospun nanofibrous microfiltration membranes (ENMs) are fabricated by using sulfonated polyvinylidene fluoride (S-PVDF)/PVDF and S-PVDF/PVDF/graphene oxide (GO) with negative charge which was prepared by electrospinning technique. The GO with different weight percentages (0, 0.1, 0.5 and 1.0wt%) was used as additive in membrane and its effect on hydrophilicity, pure water flux, mean fiber and pore diameter was studied. The results showed that the most appropriate amount of GO is 0.5wt% (low contact angle (77.08°) with high pure water flux (1222L/m2h) was obtained). Therefore, in the fabrication of the rest of the membranes 0.5wt% GO was utilized as optimal amount of GO. In addition, the effects of sulfonation on morphology, oil removal, and fouling parameters were investigated. Finally, data analysis indicated that among the novel prepared ENMs, M8 (S-PVDF/PVDF/GO-50/50=volume ratio) displayed the lower irreversible fouling (41%), the highest flux recovery ratio (59%), and the superior antifouling properties. This higher antifouling performance of the M8 compared with other novel ENMs was attributed to hydrophilicity and enhanced strong electrostatic repulsion force between the membrane matrix and the oily foulant. The low degree of total fouling (70%) for the intact PVDF nanofibrous compared with novel ENMs (91–97%) was interpreted by the bigger pore diameter (300nm) of the intact PVDF nanofibrous.

Synthesis of a monovalent selective cation exchange membrane to concentrate reverse osmosis brines by electrodialysis

In this work, novel monovalent selective cation exchange membranes (CEMs) with different mixtures of polyvinylidene fluoride (PVDF) and sulfonated PVDF (S-PVDF) were synthesized. The selected composite membranes were modified by surface polymerization of polyaniline (PANi) to improve their monovalent cation selectivity. PANi was doped with p-toluene sulfonic acid (pTSA) or l-valine (2-amino-3-methylbutanoic acid) and the selectivity of each CEM was determined. Membrane properties, such as chemical composition, water uptake, ion exchange capacity, permselectivity, contact angle and crystallinity were measured. The influence of the applied voltage was also studied. The newly developed membranes were used for electrodialytic concentration of NaCl from synthetic reverse osmosis (RO) brine. Doped membranes with pTSA (SNaMg=0.13, SNaCa=3.59) and valine (SNaMg=0.09, SNaCa=0.8) have a higher selectivity for sodium than the composite ones (SNaMg=0.63, SNaCa=6.82). Moreover, the increase of applied voltage results in an increase of the selectivity for monovalent ions.

Development of bivalent cation selective ion exchange membranes by varying molecular weight of polyaniline

A novel hybrid cation exchange membrane (CEM) composed of a blend of polyvinylidene fluoride (PVDF), sulfonated PVDF(S-PVDF) and doped polyaniline (PANi) as additive was prepared. PANi was synthesized with different molecular weights to optimize the performance of membranes for water softening. The membrane properties such as thermal behavior, membrane structure, membrane morphology and miscibility, ion exchange capacity (IEC), permselectivity, water uptake, contact angle, cell resistivity, current efficiency and electrodialysis (ED) performance were evaluated. Addition of doped PANi increased the bivalent selectivity of the cation exchange membrane. The highest bivalent selectivity and best removal of Ca2+ and Mg2+ were achieved for PANi with Mw≈45,000gmol−1 and polydispersity index (PDI)≈3.2.

Selective composite cation-exchange membrane based on S-PVDF

A novel cation-exchange membrane composed of a blend of polyvinylidene fluoride (PVDF) and sulfonated PVDF (S-PVDF) was synthesized. The membranes were prepared with different fractions of S-PVDF to optimize their performance in desalination. The ion-exchange capacity (IEC), transport number, apparent selectivity, ion conductivity, crystallinity, water uptake, contact angle, and performance in electrodialysis (ED) were evaluated. With increasing S-PVDF fractions, the transport number and permselectivity decreased, while the IEC and membrane conductivity increased. Finally, the salt extraction in ED obtained for a 70% S-PVDF membrane was 67.6%, which had a better performance than that of a commercial membrane. Also the membranes showed a good selectivity for bivalent cation removal. Membrane structure was evaluated by XRD and showed a decrease in ordering by increase in S-PVDF.

Novel composite cation exchange films based on sulfonated PVDF for electromembrane separations

A novel cation exchange membrane (CEM) composed of a blend of polyvinylidene fluoride (PVDF) and sulfonated PVDF (S-PVDF) was prepared. The membranes were prepared with different fractions of S-PVDF to optimize performance in desalination. The sulfonated polymer was characterized by FTIR, HNMR, DSC and TGA. The membrane properties such as ion exchange capacity (IEC), transport number, morphology, permselectivity, ion conductivity, water uptake, contact angle and electrodialysis (ED) performance were evaluated. Polymer characterization proved the sulfonation of PVDF and the degree of sulfonation was estimated. With increasing S-PVDF fractions, the transport number and permselectivity decreased while the IEC and ion conductivity increased. Finally, the salt extraction in ED obtained for a 70% S-PVDF membrane was 67.6%, which is a better performance than that of a commercial membrane.

Surface modification of composite ion exchange membranes by polyaniline

The aim of this work is to develop new selective cation exchange membranes (CEMs) from bivalent to monovalent selectivity by surface functional groups. So, a novel hybrid cation exchange membrane was prepared by polymerization of polyaniline on a composite membrane, made of polyvinylidene fluoride (PVDF) and sulfonated PVDF (S-PVDF). Polyaniline was doped with different doping agents and their effect on total salt extraction and selectivity of bivalent to monovalent cations was evaluated. The chemical and morphological properties of hybrid membranes were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Ion exchange capacity (IEC), transport number, ion conductivity and water uptake decreased after surface polymerization. Composite membrane has a good selectivity (∼2) for bivalent and excellent removal of both cations. The hybrid membrane, doped with pTSA has a very high selectivity for monovalent ions (∼7.1) and a high removal of monovalent ions.

Electrostatically assembled layer-by-layer composites containing graphene oxide for enhanced hydrogen gas barrier application

Hydrogen gas barrier properties of polymeric materials are a critical determinant of their practical use in hydrogen gas storage and transportation container applications. We fabricated multi-layered films containing poly(diallyldimethylammonium) chloride (PDDA) and sulfonated polyvinylidene fluoride (SPVDF)-graphene oxide (GO) composites through layer-by-layer (LBL) assembly to enhance the hydrogen gas barrier properties. Polyethylene terephthalate (PET) substrate was rendered hydrophilic by treatment with aqueous sodium hydroxide solution prior to LBL assembly construction. Positively-charged PDDA and negatively-charged SPVDF or SPVDF/GO composites were assembled by spin-coating and were tightly packed by electrostatic attraction. LBL assemblies were characterized by Fourier transform infrared (FT-IR) spectroscopy and Field emission scanning electron microscopy (FE-SEM) analyses. Electrostatic LBL assembled PDDA/SPVDF-GO films showed improved mechanical and gas barrier properties compared to their respective PDDA/SPVDF LBL assemblies without GO. The hydrogen gas transmission rate (GTR) of a 16 bi-layer LBL assembly with 2 wt.% GO was 11.7 cc/m2 d atm, which was much lower than that of PET substrate (329.1 cc/m2 d atm) and a one bi-layer LBL assembly without GO (277.9 cc/m2 d atm). The drastic decrease in GTR indicates that LBL assembled films are suitable for use in high hydrogen barrier applications.

Effect of coagulation medium on properties of sulfonated polyvinylidene fluoride membranes

AbstractThe performance and the structure of sulfonated polyvinylidene fluoride membranes prepared in different coagulation media were investigated. Several pure organic compounds and mixtures of some of them with water were used as coagulation media. The membrane were tested in an ultrafiltration laboratory unit with dextran aqueous solutions. The overall structure of the membranes was examined with the aid of the scanning electron microscope. The effect of temperature of the coagulation medium on the properties of the membranes were also investigated.

Ultrafiltration of hydrosoluble polymers. : Effect of operating conditions on the performance of the membrane

Two sulfonated polyvinylidene fluoride membranes of different porosity, prepared by the casting and gelation technique, were tested in an ultrafiltration laboratory-scale pilot plant with hydrosoluble polymer feed solutions. Polyethyleneglycols and dextrans of different average molecular weight were used as solutes for the feed solutions. Flux and rejection of the membranes were determined as functions of operating conditions (pressure, temperature and recirculation rate). The effect of properties of feed solutions (solute, concentration and molecular weight) on the performance of the membranes was also investigated.

Sulfonated Poly vinylidene Fluoride as a Biomaterial: Immobilization of Urokinase and Biocompatibility

Sulfonated Poly vinylidene Fluoride as a Biomaterial: Immobilization of Urokinase and Biocompatibility