Nanocomposite Cation Exchange Membranes Research Articles

Recent Developments on Bioinspired Cellulose Containing Polymer Nanocomposite Cation and Anion Exchange Membranes for Fuel Cells (PEMFC and AFC)

Hydrogen fuel cell (FC) technologies are being worked on as a possible replacement for fossil fuels because they produce a lot of energy and do not pollute the air. In FC, ion-exchange membranes (IEMs) are the vital components for ion transport between two porous electrodes. However, the high production cost of commercialized membranes limits their benefits. Various research has focused on cellulose-based membranes such as IEM with high proton conductivity, and mechanical, chemical, and thermal stabilities to replace the high cost of synthetic polymer materials. In this review, we focus on and explain the recent progress (from 2018 to 2022) of cellulose-containing hybrid membranes as cation exchange membranes (CEM) and anion exchange membranes (AEM) for proton exchange membrane fuel cells (PEMFC) and alkaline fuel cells (AFC). In this account, we focused primarily on the effect of cellulose materials in various membranes on the functional properties of various polymer membranes. The development of hybrid membranes with cellulose for PEMFC and AFC has been classified based on the combination of other polymers and materials. For PEMFC, the sections are associated with cellulose with Nafion, polyaryletherketone, various polymeric materials, ionic liquid, inorganic fillers, and natural materials. Moreover, the cellulose-containing AEM for AFC has been summarized in detail. Furthermore, this review explains the significance of cellulose and cellulose derivative-modified membranes during fuel cell performance. Notably, this review shows the vital information needed to improve the ion exchange membrane in PEMFC and AFC technologies.

MOF-Derived Nanoporous Carbon Incorporated in the Cation Exchange Membrane for Gradient Power Generation.

Ion exchange membranes (IEMs), as a part of the reverse electrodialysis (RED) system, play an important role in salinity gradient power (SGP) generation. Structure optimization of IEMs is critical to increase the power production by RED. In this work, metal organic framework (MOF)-derived nanoporous carbons (hollow zeolitic imidazolate framework (ZIF)-derived nanoporous carbons, HZCs) were incorporated in a sulfonated poly (2, 6-dimethyl-1,4-phenylene oxide) (sPPO) membrane to prepare an organic−inorganic nanocomposite cation exchange membrane (CEM). Physicochemical properties, electrochemical properties, and power generation of the synthesized nanocomposite membranes with different HZCs loading were characterized. The results show that the incorporated HZCs could tailor the microstructure of the membrane matrix, providing a superior performance of the nanocomposite membrane. With a HZCs loading of 1.0 wt.%, the nanocomposite membrane possessed the highest permselectivity of 77.61% and the lowest area resistance of 0.42 Ω·cm2, along with a super gross power density of 0.45 W/m2, which was 87.5% (about 1.87 times) higher than that of the blank sPPO membrane. Therefore, incorporating of an appropriate amount of HZCs in the ion-exchange membrane can improve the performance of the membrane, providing a promising method to increase the power generation of the RED system.

Nanocomposite cation-exchange membranes for wastewater electrodialysis: organic fouling, desalination performance, and toxicity testing

Organic fouling hinders the application of membrane treatment of alternative water. In this study, polyethyleneimine (PEI), titanium dioxide (TiO2) nanoparticles, and graphene oxide (GO) nanosheets were used for modifying cation-exchange membranes to enhance anti-organic fouling and desalination performance during electrodialysis of synthetical water and municipal wastewater. Fouling propensity of the unmodified and modified membranes was quantitatively evaluated by measuring organic accumulation on membrane surface using humic acid (HA, simulating natural organic matter) and bovine serum albumin (BSA, simulating organic matter in municipal wastewater effluent) as model foulants. Significant surface deposition of HA was observed on the unmodified, PEI-TiO2, and PEI-modified membrane surfaces while trivial HA fouling was detected on the PEI-GO membrane. BSA fouling was minor for all the modified membranes compared to the unmodified membrane. Desalination efficiency of electrodialysis with the modified membranes, except the PEI-modified membrane, was significantly improved in treating synthetical water with HA foulant compared to the electrodialysis with the unmodified membrane (20%~40% reduction of normalized salt removal). Relatively stable desalination behaviors were observed for each membrane system in treating BSA-containing synthetical water, and enhanced desalination was demonstrated with the modified membranes. Subsequent long-term fouling experiments with wastewater effluent revealed the superior antifouling capacity of the nanocomposite membranes (especially for the PEI-GO membrane) over 100-hour operation, while the unmodified membranes exhibited severe fouling (with total more than 60% decline of normalized salt removal) after approximately 50-hour treating wastewater. In a standard Microtox® acute toxicity assay, the nanocomposite membranes did not show any acute toxicity towards Vibrio fischeri due to potential leaching of PEI and nanomaterials, indicating safe utilization of the modified membranes for water treatment.

Advancing the conductivity-permselectivity tradeoff of electrodialysis ion-exchange membranes with sulfonated CNT nanocomposites

Ion exchange membranes, IEMs, are widely applied in water and energy technologies, such as, electrodialysis for desalination and reverse electrodialysis for sustainable power generation. However, a tradeoff between conductivity and permselectivity constrains the efficiency of IEM-based technologies. The incorporation of rationally functionalized 1-dimensional nanomaterials as fillers into the polymer matrix offers opportunities to depart from this tradeoff. In this study, we develop nanocomposite cation exchange membranes by incorporating sulfonic acid-functionalized carbon nanotubes, sCNTs, in sulfonated poly(2,6-dimethyl-1,4-phenyleneoxide) polymer matrix. The fabricated nanocomposite IEMs exhibit improved conductivity while maintaining permselectivity. Intrinsic resistivity, the reciprocal of conductivity, is lowered with greater blending of sCNTs fillers, decreasing by approximately 25% with 20 w/w% incorporation of sCNTs, while permselectivity is effectively unchanged across the different degrees of sCNT incorporation (within 2% variation). Compared with pristine membranes, the conductivity-permselectivity tradeoff line of the fabricated nanocomposite membranes is advantageously advanced, thus improving overall performance. Further characterization and analysis show a percolating network of carbon nanotubes is achieved in the polymer matrix with 10 w/w% sCNTs. We posit that the improved effective ionic conductivity is attributed to the interconnected sCNT network reducing the tortuosity of the ion transport path. This study demonstrates the promise of percolating 1D nanomaterial networks to potentially advance the conductivity-permselectivity tradeoff governing conventional IEMs.

Graphene-PSS/l-DOPA nanocomposite cation exchange membranes for electrodialysis desalination

This research reports the fabrication of nanocomposite cation exchange membranes by incorporating negatively charged graphene-based nanomaterials into a non-charged poly(vinylidene fluoride) matrix using a mold-casting technique developed in-house.

Electrostatically-coupled graphene oxide nanocomposite cation exchange membrane

We report the preparation of an electrostatically-coupled graphene oxide nanocomposite cation exchange membrane (CEM) based on sulfonic group containing graphene oxide (SGO) (45 wt % loading) and polyvinylidene fluoride (PVDF), where the ion exchange groups were provided by the SGO additive. SGO was prepared via the mixing of graphene oxide (GO) with a mixture derived from 3,4-dihydroxy-l-phenylalanine (l-DOPA) and poly(sodium 4-styrenesulfonate) (PSS). A mold-casting technique was developed to fabricate the free-standing nanocomposite CEM. The presence of sulfonic groups in the nanocomposite was confirmed with FTIR spectroscopy. Energy dispersive spectroscopy analysis showed the SGO was distributed across the entire membrane matrix, with minimal aggregation. The resultant SGO/PVDF nanocomposite CEM membrane demonstrated high hydrophilicity and high water uptake, but low swelling ratio. Furthermore, evaluation of the electrochemical properties of the nanocomposite CEM showed favorable ion exchange capacity (0.63 ± 0.08 meq/g), permselectivity (0.95 ± 0.04), and area resistance (2.8 ± 0.2 Ω cm2). The nanocomposite CEM show good potential for use in electromembrane desalination applications.

Potentiometric titration studies of poly(aniline-co-pyrrole)-Sn(IV)tungstoarsenate composite cation exchange membrane and their application as a Ni(II) selective electrode

The synthesis of poly(aniline-co-pyrrole)-Sn(IV)tungstoarsenate((PA-co-Ppy)-STA) nanocomposite cation exchange membrane was prepared through solution casting method in order to ensure the homogeneity of the obtained membrane. The synthesis of the membrane was confirmed by characterization of the nanocomposite membrane by various instrumentation techniques like Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray analysis (EDX), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD) and Thermogravimetric Analysis (TGA) techniques. The selective detection of Ni(II), having detection limit 1 × 10−9–1 × 10−1 M, the range of pH 5–8 and response time 35 s. The analytical efficacy of this electrode was built up by utilizing it as an indicator in the potentiometric titration. Various experimental parameter studies proved the absorption of Ni(II) on nanocomposite. The method used is a classical method for fabrication of an ion selective electrode and hence is easier and cost effective, other than being most precise for the detection of Ni(II) ions. Along these lines, this novel effort may be a reliable and effective to detect Ni(II) in environmental and biomedical sector in a broad scale.

High Performance Nanocomposite Cation Exchange Membrane: Effects of Functionalized Silica-Coated Magnetic Nanoparticles

Nanocomposite cation exchange membranes (CEMs) were prepared by adding various amounts of functionalized silica-coated magnetite nanoparticles to the sulfonated polyethersulfone (sPES) polymeric matrix. The particles were synthesized first by the co-precipitation method (M0). Different surface modifications were then carried out on them by grafting three functional groups of mercaptopropyl, propylsulfonic acid, and sulfonic acid to yield functionalized particles of M1, (M2, ion exchange capacity (IEC)= 3.09 meq.g-1), and (M3, IEC= 2.88 meq.g-1), respectively. The SEM images of nanocomposite membranes verified a uniform dispersion of the nanoparticles in the membrane matrix. The nanoparticles provided more ion exchange groups and regulated water content of the membrane, and consequently enhanced its transport properties, IEC, and conductivity. The maximum values of IEC and conductivity of nanocomposite membranes were 1.8 meq.g-1 and 0.274 S.cm-1 corresponded to the membranes having 3 and 2 wt% of M2 nanoparticles, respectively. The maximum ion conductivity of nanocomposite membrane was about 2 times higher than that of sPES membrane. The nanocomposite membranes containing functionalized silica-coated magnetic nanoparticles showed superior IEC, water uptake, membrane conductivity, and transport number compared to those values for the membranes containing corresponded functionalized silica nanoparticles.

PVC Based Ion-Exchange Membrane Blended with Magnesium Oxide Nanoparticles for Desalination: Fabrication, Characterization and Performance

In this study, polyvinyl chloride (PVC) based nanocomposite cation exchange membranes incorporated with magnesium oxide (MgO0 nanoparticles were fabricated by nonsolvent induced phase inversion method. The additive concentration and electrolyte conditions (concentrations/pH) were investigated. Morphology studies were done using SOM and SEM images exhibited uniform distribution of MgO nanoparticles in the membrane structure. FTIR analysis showed the chemical structure of prepared membrane that demonstrated MgO nanoparticles presence. The hydrophilicity of membranes increased when 0.5-4.0 wt.% of additive were embedded into the polymer matrix. The transport characteristics of prepared membrane were improved by increasing nanoparticle content from 0.5 to 1 wt.%. It was demonstrated that the ionic flux of developed cation exchange membranes improved with an increase in additive content up to 1 wt.%. A considerable reduction was observed in the values of electrical resistance for the prepared membrane containing MgO nanoparticles. Ionic selectivity was enhanced at the more concentered solution and was slightly decreased at higher electrolyte concentration. Moreover, at the electrolyte solution of pH7 the optimal transport properties were achieved for the membranes.

Effects of functionalized silica nanoparticles on characteristics of nanocomposites PES cation exchange membranes

Nanocomposite cation exchange membranes (CEMs) were prepared by adding various loadings of functionalized silica nanoparticles to the sulfonated polyethersulfone (sPES) polymeric matrix. The silica nanoparticles were functionalized by mercaptopropyl (F1, IEC=0), propylsulfonic acid (F2, IEC= 2.71), and sulfonic acid (F3, IEC=2.84). The properties of prepared membranes were investigated by varying the loadings of functionalized silica nanoparticles. Applying functionalized nanoparticles provides additional ion exchange groups and enhances water contents as well as conductivities and permselectivities of the membranes. The maximum IEC of 1.9 meq.g-1 was obtained for the membrane having 3wt% F3 nanoparticles and the maximum conductivity of 0.237 S·cm-1 was achieved for the membrane having 2wt% F3 nanoparticles, which were 19.6% and 64% higher than the corresponding values for sPES membrane, respectively. The excellent properties of the nanocomposite cation-exchange membranes make them appropriate candidates for electrodialysis and desalination processes.

Mechanism Exploration of Ion Transport in Nanocomposite Cation Exchange Membranes.

The origin of property enhancement of nanocomposite ion exchange membranes (IEMs) is far from being fully understood. By combining experimental work and computational modeling analysis, we could determine the influence of nanomaterials on the ion transport properties of nanocomposite cation exchange membranes (CEMs). We synthesized and characterized a series of nanocomposite CEMs by using SPPO as polymer materials and silica nanoparticles (NPs) (unsulfonated or sulfonated) as nanomaterials. We found that with the increase of NP loading, measured CEM permselectivity and swelling degree first increased and then decreased. We also found the ion exchange capacity (IEC) and ionic resistance of nanocomposite CEMs tend to be the same, regardless what type of NPs are incorporated into the membrane. Modeling analysis suggests that the change of membrane properties is related to the change in membrane microstructure. With the addition of silica NPs, membrane porosity (volume fraction of intergel phase) increases so that membranes can absorb more water. Also, volume fraction of sulfonated polymer segments increases, which can allow membranes to retain more counterions, causing membrane IEC to increase. By calculating the effective ion diffusion coefficients and membrane tortuosity factors of all the silica-NP-based CEMs synthesized in this study, along with nanocomposite CEMs from previous studies, we conclude that membrane ion transport efficiency tends to increase with the incorporation of nanomaterials. In addition, this paper presents a simulation model, which explains how the membrane property changes upon nanomaterial aggregation; the simulation results are in good agreement with the experimental data. Simulation results indicate that membrane properties are related to nanomaterial number concentration in the membrane matrices; thus, a plateau is reached for membrane ion diffusion coefficients due to the severe influence of aggregation on the increase of nanomaterial real number concentration. The results of this study can provide insight into membrane structure-property relation and contribute to the value of future designs of new nanocomposite IEMs.

Fouling resistant nanocomposite cation exchange membrane with enhanced power generation for reverse electrodialysis

Renewable energy can be generated from the mixing of seawater with river water by reverse electrodialysis (RED). As part of the RED system, ion exchange membranes (IEMs) are key factors to the success of future RED energy generation. This research presents the synthesis and characterization of a new kind of nanocomposite cation exchange membrane (CEM) by using oxidized multi-walled carbon nanotubes (O-MWCNTs) blended with sulfonated poly (2,6-dimethyl-1,4-phenylene oxide) (SPPO). The nanocomposite CEM showed simultaneous improvement of membrane anti-fouling performance and energy generation performance in RED systems. The physicochemical and electrochemical properties of nanocomposite CEMs were enhanced compared to pristine SPPO CEMs. The results indicated that the optimal inorganic loadings were 0.3–0.5wt%, which showed the best anti-fouling performance and highest power density in RED. The results show that O-MWCNTs are promising materials to improve properties of IEMs, and nanocomposite IEMs are competitive candidates for application in electrochemical systems like RED.

Effect of inorganic filler size on electrochemical performance of nanocomposite cation exchange membranes for salinity gradient power generation

Reverse electrodialysis (RED) is a technique that can capture electrical potential from mixing two water streams of different salt concentrations through permselective ion exchange membranes. Effective design of ion exchange membranes through structure optimization is critical to increase the feasibility of salinity gradient power production by RED. In this work, we present the preparation of organic–inorganic nanocomposite cation exchange membranes (CEMs) containing sulfonated polymer, poly (2,6-dimethyl-1,4-phenylene oxide), and sulfonated silica (SiO2–SO3H). The effect of silica filler size at various loading concentrations on membrane structures, electrochemical properties, and the RED power performance is investigated. The membranes containing larger fillers (70nm) at 0.5wt% SiO2–SO3H exhibited a relatively favorable electrochemical characteristic for power performance: an area resistance of 0.85Ωcm2, which is around 9.3% lower than the resistance of the membranes with smaller particle fillers (15nm). The power performance of this nanocomposite CEM in a RED stack showed the highest gross power density of 1.3Wm−2: 10% higher power output compared with the membranes containing small particle size and 21% higher than that of commercially available FKS membrane. The goal of the present work is to develop an effective design for tailor-made CEMs for RED applications. Thus, a further optimized combination of material properties and membrane structure appears to be a viable option for the development of nanocomposite ion exchange materials that could provide greater power production by RED.

Evaluation of electrochemical properties and reverse electrodialysis performance for porous cation exchange membranes with sulfate-functionalized iron oxide

Reverse electrodialysis (RED) is a process that can capture electrical energy from salinity gradients between seawater and river water through permselective ion exchange membranes. As ion exchange membranes are a key element in a RED system, enhancing their electrochemical characteristics is critical to maximizing system power performance. This study presents the preparation of porous nanocomposite cation exchange membranes via a two-step phase inversion technique. The phase inversion process controlled the structural variation (porosity) of the polymeric membranes in the presence of functionalized iron (III) oxide (Fe2O3–SO42−), which subsequently led to significantly improved electrochemical performance. A porous nanocomposite membrane containing an optimal amount of Fe2O3–SO42− (0.7wt%) at a thickness of 30µm performed best, as it had an area resistance of 0.82Ωcm2 and a permselectivity of 85.6%. Application of this membrane in a RED system achieved gross power density of up to 1.4Wm−2, which exceeds the power density obtained with the commercially available CSO (SelemionTM, Japan) membranes. Thus, effective design of ion exchange membranes through structure optimization increases the feasibility of salinity gradient power generation by RED.

Nanocomposite reverse electrodialysis (RED) ion-exchange membranes for salinity gradient power generation

Despite the important role of ion-exchange membranes (IEMs) in reverse electrodialysis (RED) systems, the current absence of proper ion-exchange membranes delays the sustainable development of the RED process for salinity gradient power generation. This research presents the preparation of a new type of organic–inorganic nanocomposite cation exchange membrane and its performance characteristics. The combination of functionalized iron (III) oxide (Fe2O3-SO42−) as an inorganic filler with the sulfonated poly (2,6-dimethyl-1,4-phenylene oxide) (sPPO) polymer matrix proved to have great potential for power generation by RED. The results showed that an optimal amount of Fe2O3-SO42− (0.5–0.7wt%) enhanced the key electrochemical properties of the ion-exchange membranes including a permselectivity up to 87.65% and an area resistance of 0.87Ωcm2. The nanocomposite membrane containing 0.7wt% (Fe2O3-SO42−) achieved a maximum power density (amount of power per unit membrane area) of 1.3Wm−2, which is relatively higher than that of the commercially available CSO (SelemionTM, Japan) membranes. The goal of the present work is to maximize the salinity gradient power generation by developing RED-specific nanocomposite IEMs. The results show the potential of the new design of the nanocomposite IEMs for viable energy generation by RED.

Fabrication and modification of polyvinylchloride based heterogeneous cation exchange membranes by simultaneously using Fe-Ni oxide nanoparticles and Ag nanolayer: Physico-chemical and antibacterial characteristics

Polyvinylchloride-blend-styrene butadiene rubber based nanocomposite cation exchange membranes were prepared by solution casting technique. Iron-oxide nanoparticles and Ag-nanolayer were simultaneously utilized as filler and surface modifier in membrane fabrication. The effects of Ag-nanolayer film thickness on membrane physicochemical and antibacterial characteristics of nanocomposite PVC-blend-SBR/Iron-oxide nanoparticles were studied. SEM images showed membrane roughness decreasing by Ag nanolayer thickness increasing. Membrane charge density and selectivity declined by Ag nanolayer coating up to 5 nm in membranes and then showed increasing trend by more nanolayer thickness. Ionic flux also showed increasing trend. Membranes showed good ability in E-Coli removal. 20 nm Ag-nanolayer coated membrane showed better performance compared to others.