Biopolymer Membranes Research Articles

Enhancing the Separation Performance of Chitosan Membranes Through the Blending with Deep Eutectic Solvents for the Pervaporation of Polar/Non-Polar Organic Mixtures

This study explores the development of chitosan-based membranes blended with three distinct deep eutectic solvents (DESs) for the pervaporation separation of methanol and methyl tert-butyl ether. DESs were selected for their eco-friendly properties and their potential to enhance membrane performance. The chitosan (CS) membranes, both crosslinked and non-crosslinked, were characterized in terms of morphology, chemical composition, wettability, mechanical resistance, and solvent uptake. Pervaporation tests revealed that incorporating DESs significantly enhanced the membranes’ selective permeability toward methanol, with up to a threefold increase in separation efficiency compared to pristine CS membranes. The membranes demonstrated a strong dependence on feed temperature, with higher temperatures improving permeation flux but reducing separation factor. Crosslinking with glutaraldehyde further increased membrane selectivity by reducing free volume into the polymer matrix. These findings underscore the potential of DESs as green additives for improving the performance of biopolymer membranes, making them promising candidates for efficient and eco-friendly organic–organic separations.

Cellulose acetate-based polymer electrolyte for energy storage application with the influence of BaTiO3 nanofillers on the electrochemical properties: A progression in biopolymer-EDLC technology

The bio-based solid polymer electrolyte serves as a promising choice for the next generation of energy storage devices to meet the requirement of green chemistry. In the current research, a green plasticized magnesium ion-conducting biopolymer electrolyte was developed using simple solution casting method for Electric Double Layer Capacitors (EDLC) applications. The biopolymer Cellulose Acetate (CA) as the host polymer, with varying concentrations of BaTiO3 as the nanofiller, Mg(CF3SO3)2 as the ionic dopant, and PEG as the plasticizer. A 2 wt% addition of BaTiO3 to the biopolymer electrolyte exhibits maximum conductivity measuring 2.4 × 10−3 S/cm. Linear Sweep Voltammetry (LSV) analysis demonstrates maximum stability voltage of 3.51 V. The ionic transference number (tion) and (tMg2+) were determined to be 0.99 and 0.41 respectively. The fabricated EDLC device with the same electrolyte showed polarisation curve without any noticeable peaks in the Cyclic Voltammetry (CV) plot, indicating no redox reactions occurring at the electrode-electrolyte interface. Galvanostatic Charge Discharge (GCD) results showed excellent coulombic efficiency, stability and Energy Density and Power Density performance over 2000 cycles. The incorporation of BaTiO3 into biopolymer membranes presents a viable approach towards sustainable energy storage solutions by enhancing the energy storage capacity of EDLC devices.

Ion transport properties and performance of gellan gum based composite polymer membrane electrolytes in proton battery and PEMFC applications

Biopolymer Gellan gum (GG) incorporated with ammonium iodide (NH₄I) salts and inorganic filler nano-TiO2 improved the ion transport facility in the salt-polymer matrix. The crystalline/amorphous nature of the membranes and the presence of n-TiO2 are evident from XRD analysis. The vibration modes corresponding to the characteristic functional groups and bonding interactions within the polymer matrix and incorporated filler materials present in the as-prepared membranes were analyzed using FTIR technique respectively. The ion transport parameters such as ionic conductivity (σ), diffusion coefficient (D), and mobility (μ), were studied using Ac impedance, transference number measurement, and FTIR deconvolution. The biopolymer membrane with the composition, 1 g GG: 0.3 M.wt% of NH4I (GGAI-3) shows the highest ionic conductivity of 2.65 ± 0.03×10−3 S/cm and on addition of 0.1 M.wt% of n-TiO2 (GGAIT-1) the increase in ionic conductivity of 4.07 ± 0.02×10−2 S/cm was observed. The H¹NMR studies help in understanding the mobility of charge carriers upon their chemical shifts. The glass transition temperature values of the as-prepared membranes were determined using DSC studies. The morphological change on the surface of the GG polymer membrane due to the addition of NH4I and n-TiO2 were analyzed using the SEM technique. The thermal, mechanical, and chemical stability of the highest ion-conducting biopolymer and composite polymer membranes were assessed using TGA, mechanical stability tests, and chemical stability tests. The IEC test exhibits the number of exchangeable ions in the polymer matrix. Utilizing the GGAI-3 and GGAIT-1 membranes as electrolytes, proton batteries were constructed and observed to have the pseudocapacitive behaviour; as the electrodes experience surface limited redox reaction at the electrode-electrolyte interface. The PEMFC cell using the GGAI- 3 and GGAIT-1 as proton exchange membrane exhibits the OCV of 646 mV and 682 mV respectively. Their performances were analyzed using the I-V polarization curve resulted with the power density of 0.14 mW/cm2and 0.34 mW/cm2 respectively.

Modelling across Multiple Scales to Design Biopolymer Membranes for Sustainable Gas Separations: 2-Multiscale Approach

The majority of materials used for membrane-based separation of gas mixtures are non-renewable and non-biodegradable, and the assessment of alternative bio-based polymers requires expensive and time-consuming experimental campaigns. This effort can be reduced by adopting suitable modelling approaches. In this series of works, we propose various modelling approaches to assess the CO2/CH4 separation performance of eight different copolymers of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV) using a limited amount of experimental data for model calibration. In part 1, we adopted a fully atomistic approach based on Molecular Dynamics (MD), while, in this work, we propose a multiscale methodology where a molecular description of the polymers is bridged to a macroscopic prediction of its gas sorption behaviour. PHBV structures were simulated using MD to obtain pressure–volume–temperature data, which were used to parametrise the Sanchez–Lacombe Equation of State. This, in turn, allows for the evaluation of the CO2 and CH4 solubility in the copolymers at various pressures and compositions with little computational effort, enabling the estimate of the sorption-based selectivity. The gas separation performance obtained with this multiscale technique was compared to results obtained with a fully atomistic model and experimental data. The solubility–selectivity for the CO2/CH4 mixture is in reasonable agreement between the two models and the experimental data. The multiscale method presented is a time-efficient alternative to fully atomistic methods and detailed experimental campaigns and can accelerate the introduction of renewable materials in different applications.

Isosorbide-based Poly(arylene ether) biopolymer membranes for gas separation

Efforts to utilize biopolymer membranes to diminish the carbon footprint of separation processes are ongoing. Herein, we report the fabrication of isosorbide (ISB)-based poly(arylene ether) biopolymer membranes, including ISB-based poly(arylene ether sulfone) (I-PAES) and ISB-based poly(arylene ether ketone) (I-PAEK) for gas separation. The robust mechanical properties and amorphous nature of ISB-based biopolymers allow for their application to gas separations. Both positron annihilation lifetime spectroscopy (PALS) and free volume analysis using density measurements reveal that replacing bisphenol A (BPA) in polysulfone (PSF) with ISB results in a significant reduction in free volume owing to the absence of bulky dimethyl groups and the presence of polar aliphatic ether groups. Substituting the sulfone group for a ketone group further decreased free volume. Solid-state CP/MAS 13C NMR analysis discloses that substituting ISB and replacing sulfonyl moieties with carbonyl groups restricts the rotational motion of internal rings, resulting in inhibited gas diffusion. Consequently, the I-PAEK membrane exhibited H2/CO2 and H2/CH4 selectivities more than three times and five times higher, respectively, compared to the PSF counterpart. Our present study demonstrates the feasibility of ISB-based poly(arylene ether) biopolymer membranes for gas separation.

Fabrication of Nanocomposite Membrane with Nanomaterial Filler for Desalination

This review aims to provide a complete overview on the modification of polymer and biopolymer membranes into nanocomposite membrane materials. Fabrication of nanocomposite membranes is carried out by incorporating inorganic filler materials in nanoparticle sizes. Nanomaterials refer to the class of materials that consist of particulate substances with any dimension of less than 100 nm at least. The properties of nanomaterials include large specific surface area, crystalline structure, shape (that regulates most of its properties as well as their unique attributes), surface morphology, and assembling phenomena. This review primarily concentrates on the recent nanotechnology-based practices to enrich the outcomes of desalination on the footings of nanocomposites, developed practicing distinct nanomaterials. A classification for various forms of nanomaterials used for building nanocomposites has also been illustrated. Special emphasis has been given to the usage of nanocomposites constructed from several nanomaterials such as nanoparticles, nanotubes, nanoshells, nanofibers, nanocapsules, nanosheets and quantum dots, and how these nanocomposites have been utilized for desalination.

Development of novel biopolymer membranes by electrospinning as potential adsorbents for toxic metal ions removal from aqueous solution

This work aims to develop novel biomembranes based on PLA, PBS, or their blend and composites, with the Cloisite® 20A nanoclay, as adsorptive materials for metal ions removal. To obtain a membrane with good morphology and thinner diameter of the fibers, a series of nonwoven mats were prepared by electrospinning. To improve the adsorption performance of the electrospun membranes, thermal and acid modifications were carried out in the nanoclay before the electrospinning process, and the final electrospun membranes were applied in the removal of Cr(VI), Cu(II), Cd(II), Zn(II), Ni(II), and Mn(II) ions present in a multi-metal solution. The PBS/PLA/C20A (80/10/10) membrane obtained with an injection flow rate of 3 mL/h, needle tip-to-collector distance of 15 cm, and voltage of 20 kV were selected for the synthesis of the adsorptive membranes, which has the best morphology due to the small average diameter of the fiber and bead-free structures. The characterization techniques (TGA, BET, helium pycnometry, RMN, and DMA) results proved that the addition of PLA and nanoclay resulted in the formation of a material more resistant and with high porosity and specific surface area than the neat PBS. It can be seen that the membranes prepared with the nanoclay after thermal modification showed high metal removal efficiency than the mats designed with the raw nanoclay and after acid modification. It was also possible to conclude that PBS and PLA present the capacity to gradually release organic carbon compounds, which can be used directly as electron donors for Cr(VI) reduction.

Microwaved-Assisted Synthesis of Starch-Based Biopolymer Membranes for Novel Green Electrochemical Energy Storage Devices.

The investigated starch biopolymer membrane was found to be a sustainable alternative to currently reported and used separators due to its properties, which were evaluated using physicochemical characterization. The molecular dynamics of the biomembrane were analyzed using low-field nuclear magnetic resonance (LF NMR) as well as Raman and infrared spectroscopy, which proved that the chemical composition of the obtained membrane did not degrade during microwave-assisted polymerization. Easily and cheaply prepared through microwave-assisted polymerization, the starch membrane was successfully used as a biodegradable membrane separating the positive and negative electrodes in electric double-layer capacitors (EDLCs). The obtained results for the electrochemical characterization via cyclic voltammetry (CV), galvanostatic charge with potential limitation (GCPL), and electrochemical impedance spectroscopy (EIS) show a capacitance of 30 F g-1 and a resistance of 2 Ohms; moreover, the longevity of the EDLC during electrochemical floating exceeded more than 200 h or a cyclic ability of 50,000 cycles. Furthermore, due to the flexibility of the membrane, it can be easily used in novel, flexible energy storage systems. This proves that this novel biomembrane can be a significant step toward ecologically friendly energy storage devices and could be considered a cheaper alternative to currently used materials, which cannot easily biodegrade over time in comparison to biopolymers.

Electrostatic capture of viruses on cationic biopolymer membranes for intra-oral disease sampling

Naso- and oropharyngeal swabs are the Center for Disease Control and Prevention (CDC) -recommended disease sampling methods for respiratory viruses. The short swabbing time for sampling by these methods may lead to variability in test results. Further, these methods are mildly invasive and can cause discomfort, tearing or gag reflexes in tested individuals. If longer sampling time is coupled with lesser patient discomfort, test reliability and patient compliance can be improved. Towards this end, we developed cationic biopolymer membranes for the electrostatic capturing of viruses in the oral cavity. Here, chemically (EDC-NHS) crosslinked uncharged chitosan (CS) nanofiber membranes were conferred either with negative surface charge by anionic poly-aspartic acid (pAsp) coating or positive charge by cationic poly-L-lysine (PLL). Consistent with our preliminary findings of dynamic light scattering (DLS) size measurements showing large agglomerates of anionic virus-like particles (VLPs) and cationic PLL in solution, a 75% increase in VLP adsorption by PLL coated CS membranes was recorded by enzyme linked immunosorbent assay (ELISA), in comparison to untreated controls. It is envisaged that the electrostatic concentration of respiratory viruses on cationic membranes can be superior alternatives to traditional swabbing in the oral cavity.

Sustainable fabrication of chitosan membranes with optimized performance for ultrafiltration

A key to the sustainable development of membrane technology is the green fabrication of biopolymer membranes, whose filtration performance is comparable to that made from petroleum-based polymers. In this study, chitosan membranes were fabricated via wet precipitation of the alkaline dope; both the composition and temperature of the coagulation bath were regulated to optimize the filtration performance for ultrafiltration. It is revealed by comparing the morphological characterization with the filtration-performance evaluation that the use of pure ethanol as the coagulant at a subzero temperature would be in favor of the formation of a laminated substructure, which can enhance the water permeance not at the cost of decreasing the rejection of micron-sized particles and macromolecules. Optical coherence tomography (OCT) was employed to in-situ characterize the film formation in an effort to understand how the variation in coagulating conditions could change the geometrical and topological characteristics of the resulting membrane. The OCT-based characterization highlights the key role of the Liesegang phenomenon in forming the hierarchical substructures, while resolving the synergistic effects emanating from the ethanol-induced film shrinkage and the structural preservation in the subzero environment.

Environmentally friendly plasticized electrolyte based on chitosan (CS): Potato starch (PS) polymers for EDLC application: Steps toward the greener energy storage devices derived from biopolymers

Biopolymer membranes derived from natural resources are environmentally friendly materials and their use for electrochemical energy storage devices has attracted a great deal of attention. Here, chitosan (CS) and potato starch (PS) doped with ammonium thiocyanate (NH4SCN) were used as host electrolyte. Various weight percent of glycerol (Gly) as a non-toxic plasticizer are used to prepare novel plasticized solid biopolymer electrolytes (PSBEs) through solution casting method, which is subsequently used as a mediator in electric double-layer capacitor (EDLC) application. Inclusion of Gly participated significantly in minimizing the crystallinity nature of the membranes as revealed by the X-ray diffraction (XRD) patterns. Fourier transform infrared (FTIR) spectroscopy revealed the complexation among the constituents of the electrolyte. Ion transport parameters determined by FTIR and electrochemical impedance spectroscopy (EIS) techniques have shown comparable results. The optimum composition of PSBE is achieved when 24 wt% of Gly is added (CPNHG3), which has shown the best ion conductivity (1.62×10−3Scm−1) from the EIS study. This film has exhibited also an excellent ion transference number (tion) of (0.989) and a large electrochemical potential stability (2.1 V) measured by transfer number measurement (TNM) and linear sweep voltammetry (LSV) methods. The restriction to ion movement was observed for the samples overloaded with Gly (32 and 40 wt%) due to the blockage effect, which reflected on ion conductivity and transport parameters. The assembled EDLC device provided a specific capacitance (Cspc) of 16.1 F/g at 10 mV/s scan rate with no sign of redox reaction, which was proven by either cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) techniques. Further, the cyclic stability and high performance of the EDLC regarding energy density, power density, and coulombic efficiency were confirmed throughout the 2500 cycles.

Modelling across Multiple Scales to Design Biopolymer Membranes for Sustainable Gas Separations: 1—Atomistic Approach

In this work, we assessed the CO2 and CH4 sorption and transport in copolymers of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV), which showed good CO2 capture potential in our previous papers, thanks to their good solubility-selectivity, and are potential biodegradable alternatives to standard membrane-separation materials. Experimental tests were carried out on a commercial material containing 8% of 3-hydroxyvalerate (HV), while molecular modelling was used to screen the performance of the copolymers across the entire composition range by simulating structures with 0%, 8%, 60%, and 100% HV, with the aim to provide a guide for the selection of the membrane material. The polymers were simulated using molecular dynamics (MD) models and validated against experimental density, solubility parameters, and X-ray diffraction. The CO2/CH4 solubility-selectivity predicted by the Widom insertion method is in good agreement with experimental data, while the diffusivity-selectivity obtained via mean square displacement is somewhat overestimated. Overall, simulations indicate promising behaviour for the homopolymer containing 100% of HV. In part 2 of this series of papers, we will investigate the same biomaterials using a macroscopic model for polymers and compare the accuracy and performance of the two approaches.

Sustainable Plant-Based Biopolymer Membranes for PEM Fuel Cells

Carboxycellulose nanofibers (CNFs) promise to be a sustainable and inexpensive alternative material for polymer electrolyte membranes compared to the expensive commercial Nafion membrane. However, its practical applications have been limited by its relatively low performance and reduced mechanical properties under typical operating conditions. In this study, carboxycellulose nanofibers were derived from wood pulp by TEMPO oxidation of the hydroxyl group present on the C6 position of the cellulose chain. Then, citric acid cross-linked CNF membranes were prepared by a solvent casting method to enhance performance. Results from FT-IR spectroscopy, 13C NMR spectroscopy, and XRD reveal a chemical cross-link between the citric acid and CNF, and the optimal fuel cell performance was obtained by cross-linking 70 mL of 0.20 wt % CNF suspension with 300 µL of 1.0 M citric acid solution. The membrane electrode assemblies (MEAs), operated in an oxygen atmosphere, exhibited the maximum power density of 27.7 mW cm-2 and the maximum current density of 111.8 mA cm-2 at 80 °C and 100% relative humidity (RH) for the citric acid cross-linked CNF membrane with 0.1 mg cm-2 Pt loading on the anode and cathode, which is approximately 30 times and 22 times better, respectively, than the uncross-linked CNF film. A minimum activation energy of 0.27 eV is achieved with the best-performing citric acid cross-linked CNF membrane, and a proton conductivity of 9.4 mS cm-1 is obtained at 80 °C. The surface morphology of carboxycellulose nanofibers and corresponding membranes were characterized by FIB/SEM, SEM/EDX, TEM, and AFM techniques. The effect of citric acid on the mechanical properties of the membrane was assessed by tensile strength DMA.

Biodegradable flexible proton conducting solid biopolymer membranes based on pectin and ammonium salt for electrochemical applications

One of the most significant difficulties confronting civilization today is the availability of renewable power generation for a growing and highly productive society. Solid-state batteries are expected to be advantageous in a wide variety of energy storage systems. The present work examines the synthesis and characterization of solid biopolymer membranes as electrolytes for solid-state primary proton battery applications from the viewpoint of renewable energy development. Solid biopolymer membranes (SBPMs) based on anionic polysaccharide host polymer pectin and proton donor ammonium iodide (AI) salt are synthesized via a facile solution cast technique. The impact of dopant salt concentration (30 M.wt % to 80 M.wt %) on the membranes' electrical, dielectric, transport, thermal, structural, and electrochemical properties was investigated. At ambient temperature, a maximum ionic conductivity of 4.5 × 10−3 S cm−1 has been achieved. The dielectric and transport properties of the prepared SBPMs are studied and correlated with the trend of ionic conductivity. With the highest conductive SBPM, the primary proton battery has been assembled. The discharge performance and open circuit voltage (OCV) were examined and recommended as a potential candidate for alternate research for low power density applications.

Sustainable Lithium‐Ion Battery Separator Membranes Based on Carrageenan Biopolymer

Aiming to improve the sustainability of materials for lithium‐ion batteries (LIBs), this work reports on the development of novel membranes based on iota‐carrageenan biopolymer and their suitability as separator in LIBs applications. The membranes are prepared by freeze‐drying and its morphology, thermal, mechanical, and electrochemical properties are evaluated as a function of polymer concentration in the solution. Porous membranes with a degree of porosity above 90% and different interconnected pore sizes between 50 and 70 µm for both polymer concentrations are obtained. The electrochemical parameters of the membranes are influenced by the carrageenan polymer concentration, being 1.34 mS cm‐1, 3, 7, and 0.48 for ionic conductivity, tortuosity, MacMullin number, and lithium transference number, respectively, for the membrane prepared from the 4 wt% carrageenan content solution. The half‐cells cathodic prepared with the developed membranes show good cyclability and rate capability. The discharge capacity values obtained with the membrane prepared from 4 wt% carrageenan content are 145 and 25 mAh g‐1 at C/10‐ and 1C‐rates, respectively, demonstrating excellent battery cycling performance and long‐term stability. Thus, this work demonstrates that iota‐carrageenan biopolymer membranes developed by freeze‐drying can be used as separators for a next generation of more sustainable batteries.

Hybrid cross-linked chitosan/protonated-proline:glucose DES membranes with superior pervaporation performance for ethanol dehydration

This work explores a protonated L-proline:glucose (molar ratio 5:1) deep eutectic solvent (DES) in fabricating biopolymer membranes utilizing chitosan (CS). Initially, the miscibility of CS and DES to prepare homogeneous dense blend membranes has been investigated. Different techniques, such as scanning electron microscopy, contact angle (CA), atomic force microscopy (AFM), Fourier transformed infrared spectroscopy (FTIR) and swelling degree (uptake), were used to characterize the structure of the resulting membranes. Within the pervaporation performance for ethanol dehydration, Arrhenius and mass transfer analysis were analysed in detail. Interestingly, the addition of DESs provided superior performance to crosslinked CS: DES membranes compared with the ones lacking DES. Based on the morphology and properties observed, this new concept of CS-based membranes can be alternatively applied in other solvent separations requiring hydrophilic membranes.

Novel bio-polymer based membranes for CO2/CH4 separation

This work deals with the utilization of the poly(lactic acid) (PLA) to fabricate biopolymer membranes by phase inversion technique for the treatment of gaseous streams rich in CO2 and CH4. PLA is an excellent biopolymer constituting a viable option to most of the traditional fossil-based polymers, possessing zero environmental impact once exhausted and interesting gas separation properties as membranes. Several parameters of the phase inversion process were studied in order to identify the optimal PLA membrane preparation, as a function of the best performance in terms of ideal CO2/CH4 selectivity, CO2 permeability and membrane degradability. The PLA membranes were fully characterized in terms of morphology, thickness, differential scanning calorimetry, Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy analyses. Afterwards, single gas permeation tests were performed in order to prove the relevance of PLA membranes in CO2/CH4 separation, and membrane degradation tests under water as well. The results of the wide experimental campaign on PLA membranes preparation evidenced how specific membrane samples (thickness > 25 μm) possess quite high CO2/CH4 ideal selectivity (between 220 and 230) and CO2 permeability ∼ 11 Barrer at ambient temperature, which allowed to collocate this biopolymer based membrane material above the correspondent Robeson's upper bound.

Composite chitosan and quaternary ammonium modified nanofibrillar cellulose anion exchange membranes for direct ethanol fuel cell applications

Fuel cells are a promising technology for energy production, but their commercialization is hindered mainly due to high costs. Direct alkaline ethanol fuel cells (DAFC) are receiving increasing attention as they can utilize cheaper, non-precious metal catalysts. A vital component of a DAFC is the anion exchange membrane (AEM). Currently, the commercially available AEMs don’t possess satisfactory properties. This indicates a need for the development of new highly efficient, environmentally friendly, and economically viable AEMs. Synthesis of synthetic polymer AEMs is usually complex and time-consuming, as well as environmentally unfriendly. Therefore, it is highly desired that the membrane material is bio-renewable, non-toxic and environmentally benign. In this work, a series of biopolymer membranes were designed by a simple, cost-effective, dispersion-casting procedure, fully complying with green-chemistry principles. Design of experiments was used as a methodology for identifying optimal combinations of influencing factors and their relations within selected responses. The obtained chitosan-Mg(OH)2 composite membranes containing modified nanofibrillar cellulose (CNF) fillers with quaternary ammonium groups were investigated for their mechanical properties, swelling ratio, ethanol permeability and ion exchange properties. Obtained data suggest the applicability of newly prepared, biopolymeric composites as eco-friendly AEMs in DAFC technologies.

Lithium ion conducting biopolymer membrane based on kappa carrageenan with LiCl and its application to electrochemical devices

A lithium ion conducting solid biopolymer membrane (SBE) has been prepared by incorporating lithium chloride salt (LiCl) with the biopolymer K- Carrageenan (Kappa Carrageenan) using solution casting technique. One gram Kappa Carrageenan with 0.5 g LiCl yields ionic conductivity value of 1.15 × 10-2 Scm−1 which has been found by using Ac impedance analysis. The highest conducting biopolymer membrane possesses high amorphous nature among all the prepared biopolymer membranes, and XRD analysis confirms it. Highest conducting biopolymer possesses low crystallinity percentage of 8.18. Transference number analysis by Wagner’s polarization technique provides information that the major contribution for the conductivity is given by ions whereas minor contribution has been given by electrons. Transference number of ions is found to be 0.96 whereas transference number of electrons is 0.04. By using the using highest conducting composition (one gram Kappa Carrageenan: 0.5 g LiCl) as electrolyte, LiFePO4 as cathode and activated charcoal/graphite as anode, rechargeable lithium-ion conducting battery has been constructed and its voltage is found as 3.25 V. The performance of the battery has been studied by connecting a load (100 kΩ).

Chitin and chitin-cellulose composite hydrogels prepared by ionic liquid-based process as the novel electrolytes for electrochemical capacitors

This paper reports on the preparation and electrochemical performance of chitin- and chitin-cellulose-based hydrogel electrolytes. The materials were prepared by a casting solution technique using ionic liquid-based solvents. The method of chitin dissolution in ionic liquid with the assistance of dimethyl sulfoxide co-solvent was investigated. The obtained membranes were soaked with 1-M lithium sulfate aqueous solution. The prepared materials were preliminarily characterized in terms of structural and physicochemical properties. Further, the most promising biopolymer membranes were assembled with activated carbon cloth electrodes in symmetric electrochemical capacitor cells. The electrochemical performances of these devices were studied in a 2-electrode system by commonly known electrochemical techniques, such as cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. The devices operated at a maximum voltage of 0.8 V. All the investigated materials have shown high efficiency in terms of specific capacitance, power density, and cyclability. The studied capacitors exhibited specific capacitance values in the range of 92–98 F g−1, with excellent capacitance retention (ca. 97–98%) after 20,000 galvanostatic charge and discharge cycles. Taking into account the above information and the eco-friendly nature of the biopolymer, it appears that the prepared chitin- and chitin-cellulose-based hydrogel electrolytes can be promising components for green electrochemical capacitors.