Pure Chitosan Membrane Research Articles

Preparation and characterization of chitosan-based corn protein composites constructed with TG enzyme and their preservation performance on strawberries

This study describes the synthesis of Chitosan - corn protein (CSZ-TG) composites using TG enzyme (TG) as a cross-linking agent and the preparation of chitosan-based composite membrane material (CSZEO-TG) by blending citrus essential oil (EO) with the synthesized CSZ-TG. The prepared composite membrane material was used for fresh strawberry preservation and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-spectral diffraction, tensile properties, and water vapor and CO2 permeability. Scanning electron microscopy results showed a smooth surface of the composite membrane material after the addition of TG enzyme, while Fourier transforms infrared spectroscopy results showed a structural change of the composite membrane material after the addition of corn protein (Z). The tensile results showed an increase in the tensile strength of the composite membrane material after the addition of TG enzyme, while the flexibility of the composite membrane material was enhanced after the addition of EO. Compared with the pure chitosan membrane (CS), the water vapor and CO2 barrier properties of the composite membrane material after the addition of Z, TG, and EO did not change much, and they all showed better water vapor barrier properties. The results of the antioxidant analysis of the solution of the CSZEO-TG composite membrane material showed that the composite membrane material had efficient antioxidant properties. The effects of the composite film material on the storage period and quality of strawberries were evaluated by the indicators of weight loss, hardness, decay rate, soluble solids, titratable acid content, MDA content, and the content of four enzymes, SOD, POD, PPO and CAT. Comprehensive freshness data analysis showed that CSZEO-TG had the best freshness preservation performance and effectively extended the shelf life of strawberries.

Enhanced dye adsorption with conductive polyaniline doped chitosan nanofibrous membranes

Polyaniline is widely used in the field of electrochemistry due to its excellent electrical conductivity. However, its effectiveness and mechanism of enhancing adsorption property are unclear. Herein, chitosan/polyaniline nanofibrous composite membranes with average diameter ranging from 200 to 300 nm were fabricated by electrospinning technology. The as-prepared nanofibrous membranes exhibited significantly improved adsorption capacity of 814.9 mg/g and 618.0 mg/g towards acid blue 113 and reactive orange dyes, which were 121.8 % and 99.4 % higher than that of pure chitosan membrane. The doped polyaniline promoted the dye transfer rate and capacity due to the enhanced conductivity of the composite membrane. Kinetic data showed that chemisorption was the rate-limiting step, and thermodynamic data indicated the adsorption of the two anionic dyes was spontaneous monolayer adsorption. This study provides a feasible strategy to introduce conductive polymer into adsorbent to construct high performance adsorbents for wastewater treatment.

Blend of Multi-Walled Carbon Nanotubes and Quercetin Improves Physicochemical Properties of Chitosan Membrane for Wound Dressing Application

Although wound dressings are essential to protect wound from infection, these wound care products have limited function in facilitating wound healing. This study aimed to synthesize multi-walled carbon nanotube (MWCNT)/quercetin (QUE)/chitosan (CS) blended composite membrane and analyze their physicochemical properties for wound dressing application in comparison to the pure chitosan (CS) membrane. The MWCNT/QUE/CS blended membranes were prepared by mixing CS, QUE and MWCNT at a ratio of 3:1:1 using a solvent casting method. The membranes were analyzed physicochemically for their surface morphology, elemental composition, structural composition, wettability, water vapor transmission rate (WVTR) and swelling properties and were compared to the pure CS membrane. The findings pointed out that the blend of MWCNTs and QUE in the CS matrix produces a membrane with uneven and more hydrophilic surface with water contact angle of 64.70°± 3.7 and low WVTR of 16.26 g/m2.day after 24 h. The swelling analysis showed that the blended membrane was able to absorb more than 60% of water within 10 minutes, although lower than the pure CS membrane. This study revealed that MWCNT/QUE/CS blended membrane could possibly be used as a wound dressing as it may promote moist environment needed for wound healing in addition to its antibacterial and antioxidant properties that may accelerate wound healing process.

Preparation of Chitosan/β-Cyclodextrin Composite Membrane and Its Adsorption Mechanism for Proteins.

A significant portion of the protein in food waste will contaminate the water. The chitosan/modified β-cyclodextrin (CS/β-CDP) composite membranes were prepared for the adsorption of bovine serum albumin (BSA) in this work to solve the problem of poor adsorption protein performance and easy disintegration by a pure chitosan membrane. A thorough investigation was conducted into the effects of the preparation conditions (the mass ratio of CS and β-CDP, preparation temperature, and glutaraldehyde addition) and adsorption conditions (temperature and pH) on the created CS/β-CDP composite membrane. The physical and chemical properties of pure CS membrane and CS/β-CDP composite membrane were investigated. The results showed that CS/β-CDP composite membrane has better tensile strength, elongation at break, Young's modulus, contact angle properties, and lower swelling degree. The physicochemical and morphological attributes of composite membranes before and after the adsorption of BSA were characterized by SEM, FT-IR, and XRD. The results showed that the CS/β-CDP composite membrane adsorbed BSA by both physical and chemical mechanisms, and the adsorption isotherm, kinetics, and thermodynamic experiments further confirmed its adsorption mechanism. As a result, the CS/β-CDP composite membrane of absorbing BSA was successfully fabricated, demonstrating the potential application prospect in environmental protection.

Comparative Studies on the Proton Conductivities of Hafnium-Based Metal-Organic Frameworks and Related Chitosan or Nafion Composite Membranes.

Hafnium (Hf)-based UiO-66 series metal-organic frameworks (MOFs) have been widely studied on gas storage, gas separation, reduction reaction, and other aspects since they were first prepared in 2012, but there are few studies on proton conductivity. In this work, one Hf-based MOF, Hf-UiO-66-fum showing UiO-66 structure, also known as MOF-801-Hf, was synthesized at room temperature using cheap fumaric acid as the bridging ligand, and then imidazole units were successfully introduced into MOF-801-Hf to obatin a doped product, Im@MOF-801-Hf. Note that both MOF-801-Hf and Im@MOF-801-Hf demonstrate excellent thermal, water, and acid-base stabilities. Expectedly, the maximum proton conductivity (σ) of Im@MOF-801-Hf (1.46 × 10-2 S·cm-1) is nearly 4 times greater than that of MOF-801-Hf (3.98 × 10-3 S·cm-1) under 100 °C and 98% relative humidity (RH). To explore their possible practical application value, we doped them into chitosan (CS) or Nafion membranes as fillers, namely, CS/MOF-801-Hf-X, CS/Im@MOF-801-Hf-Y, and Nafion/MOF-801-Hf-Z (X, Y, and Z are the doping percentages of MOF in the membrane, respectively). Intriguingly, it was found that CS/MOF-801-Hf-6 and CS/Im@MOF-801-Hf-4 indicated the highest σ values of 1.73 × 10-2 and 2.14 × 10-2 S·cm-1, respectively, under 100 °C and 98% RH and Nafion/MOF-801-Hf-9 also revealed a high σ value of 4.87 × 10-2 S·cm-1 under 80 °C and 98% RH, which showed varying degrees of enhancement compared to the original MOFs or pure CS and Nafion membranes. Our study illustrates that these Hf-based MOFs and related composite membranes offer great potential in electrochemical fields.

Synthesis and Characterization of Chitosan/Alginate/Mesoporous Phosphotungstic Acid Electrolyte Membranes for Direct Methanol Fuel Cell Applications

In this study, chitosan (Chi), alginate (Alg), and mesoporous phosphotungstic acid (mPTA) were used as electrolyte membrane materials for DMFC. Chi and Alg will be crosslinked with mPTA filler to improve the performance of the electrolyte membrane. Characterizations carried out include tensile tests, methanol permeability, and proton conductivity. The results of the tensile test showed that the Chi-Alg(3:1) membrane had a higher tensile strength value (26.64 N/mm2) than the pure chitosan membrane (11.97 N/mm2). The results of methanol permeability show that the Chi-Alg(3:1)/mPTA(2.0%) membrane has a lower methanol permeability value (8.17 × 10-6 cm2 s-1) and a relatively high proton conductivity value, (45.8 × 10-3 S cm-1). Chi-Alg/mPTA membrane, simplicity of the used simple preparation method and the cost reduction can be applied as an electrolyte membrane for DMFC.

Efficient separation of methanol/dimethyl carbonate mixtures by UiO-66 MOF incorporated chitosan mixed-matrix membrane

Pervaporation shows great potential in separation of organic-organic mixtures that are widely involved in chemical and petrochemical industries, while the separation performance of polymeric membranes is undesirable for practical application. In this work, we incorporated UiO-66 (ZrCl4) metal-organic frameworks (MOFs) into chitosan (CS) membrane to separate methanol-dimethyl carbonate (DMC) mixtures. ZrOCl2·8H2O or ZrCl4 was selected as metal precursor to synthesize UiO-66, which aimed to investigate the structural defect of UiO-66 for the separation performance of mixed matrix membranes (MMMs). BET, 1H NMR and low-angle XRD characterizations indicated that UiO-66 (ZrCl4) with appropriate pore size is more suitable for preferentially permeate methanol over DMC. IR, dielectric relaxation and DSC characterizations combined with molecular simulations revealed the ideal interfacial morphology of UiO-66/CS MMMs was owing to the favorable molecular interactions including hydrogen bond interaction and van der Waals interaction. Pervaporation separation of methanol-DMC mixtures demonstrated that UiO-66 (ZrCl4) nanofillers can simultaneously enhance the permeation flux and separation factor of CS membrane. The optimized 10 wt% UiO-66 (ZrCl4)/CS MMM exhibited total flux and methanol/DMC separation factor of 355 g/m2h and 337 for 10 wt% methanol-DMC mixtures at 50 °C, which were 3.4-fold and 25-fold higher than that of the pure CS membrane, respectively, and outperformed the state-of-the-arts polymer-based membranes.

Effect of sodium alginate/phosphate-stabilized amorphous calcium carbonate nanoparticles on chitosan membranes

Biodegradable chitosan (CS) films can meet the demand for sustainable development. However, the performance of pure CS membrane still exists a particular gap compared with the traditional film. Inorganic nanomaterials with the controllable release are added to improve its physical and chemical properties. Herein, a series of CS/phosphate-stabilized amorphous calcium carbonate (CS/ACCP) and CS/sodium alginate/ACCP (CS/Alginate/ACCP) composite films were prepared by the flow method. The effects of ACCP and Alginate/ACCP nanoparticles on the physical and chemical properties of the composite membrane were investigated. The results showed that the composite nanoparticles could significantly improve CS film's compactness, hydrophobicity, and mechanical properties and enhance its ultraviolet (UV) blocking ability, water resistance, and water vapor blocking ability. When the number of nanoparticles was 8%, the mechanical properties of the CS composite membrane reached optimum value, and the comprehensive performance was better. In addition, the controlled-release properties of CS composite membranes were also studied, and the antioxidant, antibacterial, biocompatibility, and fresh-keeping effects of the composite membranes were explored. The results indicated that the CS composite membranes had not only excellent bacteriostatic (72%) properties (Escherichia coli) but also presented well fruit preservation (15 days) properties (sugar orange). In particular, the controlled release range of CS composite membrane at 12 h was between 30% and 90%, which provided a theoretical basis for its use as an edible membrane. Therefore, based on ACCP and Alginate/ACCP nanoparticles, CS composite membranes with more excellent application value in the biological field were prepared through further optimization design.

Dual-Functional Coordination Polymer with High Proton Conductivity and a Low-Detection-Limit Fluorescent Probe.

A coordination polymer with dual functions of high proton conductivity and highly sensitive fluorescent sensors demonstrates a great application potential. In this work, a cadmium-based coordination polymer (denoted as CP 1) with hydrothermal stability was synthesized. The abundant coordination water, lattice water, and amino groups make an extended hydrogen-bonding pathway for efficient proton migration, which endows CP 1 with the highest proton conductivity of 2.41 × 10-3 S·cm-1 at 353 K and 98% RH. Especially, the proton conductivity of the chitosan (CS) hybrid membrane containing CP 1 reaches a maximum value of 2.62 × 10-2 S·cm-1 under 343 K and 98% RH, which increases almost 7 times higher than that of the pure CS membrane due to the host-guest collaboration. Furthermore, luminescence studies revealed that CP 1 is a high-sensitivity and good-selectivity fluorescent probe for the detection of trace amounts of l-histidine with a lowest detection limit of 1.0 × 10-8 M.

Bioactive Glass Flakes as Innovative Fillers in Chitosan Membranes for Guided Bone Regeneration

Herein, novel bioactive glass flakes (BGFs) (45S5 composition), obtained by compression in the liquid phase in a stirred media mill, are combined with chitosan (CS) to develop composite membranes using solvent casting for guided bone regeneration (GBR). The incorporation of BGFs endows CS membranes with superior bioactivity as evidenced by rapid hydroxyapatite formation after 3 days of immersion in simulated body fluid (SBF). Moreover, the addition of BGFs reduces the swelling ratio of CS membranes, beneficial for GBR applications. The swelling behavior can also be modulated by tuning the added amount of BGFs. In vitro cell studies indicate the noncytotoxicity of composite membranes toward osteoblast cell line MC3T3‐E1, although the presence of BGFs slightly reduces the cell viability compared to pure CS membranes. The incorporation of BGFs also improves the osteogenic differentiation of MC3T3‐E1 cells as indicated by the enhanced alkaline phosphatase activity. The results show the feasibility of BGFs as anisotropic bioactive fillers in polymeric matrices. In conclusion, the developed CS‐BGF composite membranes show promising potential as a novel material for GBR.

The Construction and Application of Dual‐Modified Carbon Nanotubes in Proton Exchange Membranes with Enhanced Performances

AbstractIn this study, the carbon nanotubes (CNTs) are successively coated via sol‐gel method with SiO2(SiO2@CNTs), followed by grafting with 3‐merraptnpropyltrimethnxysilane and oxidation with hydrogen peroxide to yield dual‐modified CNTs (SSiO2@CNTs). The SSiO2@CNTs material is applied to prepared chitosan (CS) based composite proton exchange membranes by the incorporation of various content of SSiO2@CNTs, the structure and properties of as‐prepared composite membranes are fully investigated. Compared to pristine CS membrane, the SSiO2@CNTs‐filled composite membranes show improved thermal stability, mechanical stability, and methanol resistance, owing to the effective interface interaction and good compatibility between SSiO2@CNTs and CS matrix. Additionally, the doping of SSiO2@CNTs also generates a positive effect on the electrochemistry performance, due to the construction of abundant transport channel and providing more proton sources or proton sites. Particularly, the CS/SSiO2@CNTs‐7 membrane exhibits tensile strength of about 40.1 MPa and proton conductivity of 35.8 mS cm−1at 80 °C, which is almost 1.6 and 2.0 times higher than pure CS membrane, and lower methanol permeability of 0.9 × 10−6 cm2 s−1. The direct methanol fuel cell performance (DMFC) of CS/SSiO2@CNTs‐7 membrane is also improved with open circuit voltage of 0.67 V and maximum power density of 60.7 mW cm−2at 70 °C.

SUSTAINABLE CELLULOSE NANOCRYSTAL REINFORCED CHITOSAN/HPMC BIO-NANOCOMPOSITE FILMS CONTAINING MENTHOL OIL AS PACKAGING MATERIALS

There is a growing demand to develop biodegradable composite films, with enhanced water resistance, antimicrobial activity, high mechanical properties and low oxygen permeability. In the present study, chitosan/hydroxypropyl methylcellulose (HPMC) films reinforced with cellulose nanocrystal (CNC) and containing menthol oil were prepared for food packaging applications. Menthol oil was selected due to its antibacterial properties, as well as relatively low cost and wide availability. CNC was prepared from bagasse via acid degradation. The bio-composites were prepared through a simple and versatile solution mixing and casting method. The morphology, chemical composition, water absorption, mechanical properties and antibacterial activity of the films were investigated. FTIR spectra were used to evaluate the film structure in terms of the interactions between components. Data showed that the addition of CNC improved the mechanical properties of the formed films and the menthol oil enhanced their antibacterial properties. HPMC and HPMC/CNC reduced the water absorption of the pure chitosan membrane from 70% to 22% and 9-11% by weight, respectively, which makes these constituents a good alternative for producing packaging.

Composite Proton Exchange Membranes Based on Chitosan and Phosphotungstic Acid Immobilized One-Dimensional Attapulgite for Direct Methanol Fuel Cells.

In order to obtain biopolymer chitosan-based proton exchange membranes with excellent mechanical properties as well as high ionic conductivity at the same time, natural attapulgite (AT) with one-dimensional (1D) structure was loaded with a strong heteropolyacid and also a super proton conductor, phosphotungstic acid (PWA), using a facial method. The obtained PWA anchored attapulgite (WQAT) was then doped into the chitosan matrix to prepare a series of Chitosan (CS)/WQAT composite membranes. The PWA coating could improve the dispersion and interfacial bonding between the nano-additive and polymer matrix, thus increasing the mechanical strength. Moreover, the ultra-strong proton conduction ability of PWA together with the interaction between positively charged CS chains and negatively charged PWA can construct effective proton transport channels with the help of 1D AT. The proton conductivity of the composite membrane (4 wt.% WQAT loading) reached 35.3 mS cm−1 at 80 °C, which was 31.8% higher than that of the pure CS membrane. Moreover, due to the decreased methanol permeability and increased conductivity, the composite membrane with 4% WQAT content exhibited a peak power density of 70.26 mW cm−2 fed at 2 M methanol, whereas the pure CS membrane displayed only 40.08 mW cm−2.

Enhanced proton conductivities of chitosan-based membranes by inorganic solid superacid SO42−–TiO2 coated carbon nanotubes

To increase proton conductivity of chitosan (CS) based polymer electrolyte membranes, a novel nanofiller-solid superacide SO42--TiO2 (STi) coated carbon nanotubes (STi@CNTs) are introduced into CS matrix to fabricate membranes for polymer electrolyte membrane fuel cells (PEMFCs). Owing to the STi coating, the dispersion ability of CNTs and interfacial bonding are obviously improved, hence, CNTs can more fully play their reinforcing role, which makes the CS/STi@CNTs composite membranes exhibit better mechanical properties than that of pure CS membrane. More importantly, STi possesses excellent proton transport ability and may create facile proton transport channels in the membranes with the help of high aspect ratio of CNTs. Particularly, the CS/STi@CNTs-1 membrane (1 wt% STi@CNTs loading) obtains the highest proton conductivity of 4.2 × 10−2 S cm–1 at 80 °C, enhancing by 80% when compared with that of pure CS membrane. In addition, the STi@CNTs also confer the composite membranes low methanol crossover and outstanding cell performance. The maximum power density of the CS/STi@CNTs-1 membrane is 60.7 mW cm−2 (5 M methanol concentration, 70 °C), while pure CS membrane produces the peak power density of only 39.8 mW cm−2.

Chitosan-based glycerol-plasticized membranes: bactericidal and fibroblast cellular growth properties

Chitosan-based glycerol-plasticized membranes were prepared aiming to develop low-cost and biocompatible material for wound dressing. They were produced by casting/solvent evaporation, and their formation mechanisms were attributed to intra- and inter-hydrogen bonds between materials. The results show that the glycerol acted as plasticizer and changed the proliferation of fibroblast cells on chitosan membranes. A high increase in the contact angle between water and membrane was observed comparing pure chitosan (more hydrophilic) and chitosan-glycerol (more hydrophobic) membranes. The angle values were found to be ~ 40 and ~ 130 degrees for chitosan and chitosan/glycerol 30% (w/w) membranes, respectively. In comparison with pure chitosan, glycerol-mixed membranes showed lower glass transition temperatures and are less brittle when handling. The antibacterial properties of such membranes against Gram-negative (E. coli) and Gram-positive (S. aureus and B. Cereus) microorganisms were tested, showing efficient growth inhibition. In vitro studies over fibroblast cells using plasticized membranes demonstrated good viability and enhanced cell proliferation in comparison with those composed of pure chitosan. Such results suggest that the as-prepared chitosan-glycerol membrane is a promising material for use as wound dressing in tissue engineering applications.

Chitosan/silica composite membrane: Performance on water permeability and rejection of lead(II) ion from aqueous solution

Heavy metal such as lead can be classified as non-biodegradable inorganic pollutants which can contaminate the soils, ground water, sediments and surface water. It cannot be broken down or decomposed by living organism and can continue to exist over a prolonged period, generating harmful effects to the living things. Thus, lead removal is necessary in order to reduce the amount of heavy metals contaminated in water. The purpose of this study was to fabricate chitosan/silica based composite membrane for removal of Pb(II) metal ions from aqueous solution by membrane filtration technique. The composite membranes were characterized in terms of morphological studies and functional group analysis by using Scanning Electron Microscopy (SEM) and Fourier Transform Infrared-Attenuated Total Reflectance (FTIR-ATR) analysis, respectively. The membrane permeation performance, in terms of water permeability and rejection of Pb(II) ions from aqueous solution, was conducted by using membrane permeation system. SEM images illustrated that the presence of macrovoids on the cross-section of the chitosan/silica composite membrane has improved the morphology of pure chitosan membrane and assisted in the rejection of Pb(II) ions. Meanwhile, FTIR-ATR spectra showed the presence of new adsorption peaks, contributed by silica interaction with hydroxyl group of chitosan. The addition of silica to chitosan membrane has significantly enhanced the pure water permeability from 37.36 L/m2h to 42.43 L/m2h. Furthermore, the rejection of Pb(II) metal ions by chitosan/silica composite membrane was slightly higher compared to pure chitosan membrane with the removal efficiency of 13.78% at 0.5 bar applied pressure. These findings indicates the potential use of silica to improve chitosan membrane properties and reduce heavy metal pollution in water.

The potential of the composite membranes Ch-AgNP to recover silver from X-ray film processing wastes

The potential of the composite membranes chitosan-silver nanoparticles (Ch-AgNP) to remove silver (Ag) from X-ray film processing wastes was studied using a filtration method. The study includes the pure water flux (PWF), product flux (PF), and rejection coefficient (R). Several of composite membranes such as Ch-AgNP10, Ch-AgNP100, Ch-AgNP250, Ch-AgNP500, and a pure chitosan membrane (Ch) were used in this study. The filtration was carried out using a dead-end filtration method with a pressure of 260-270 kPa. The concentration of silver waste was determined using Atomic Absorption Spectroscopy (AAS). The results showed that the composite membranes have a better ability to filter silver from X-ray film processing wastes than the pure chitosan membrane. The highest rejection coefficient (R) gave by Ch-AgNP100 of around 95.55% with the pure water flux and product flux of 2051.03 and 1192.28 L/m2·h, respectively. The rejection coefficient of the composite membranes increased with increasing the mass of silver nanoparticles, while the PWF and PF were decreased. These results indicated that chitosan composite membranes are a potential method for recovering silver from X-ray film processing wastes. It’s a safe and environmentally friendly method.

Carbon nanocomposites self‐assembly UiO‐66‐doped chitosan proton exchange membrane with enhanced proton conductivity

One-dimensional (1D) sodium ligninsulfonate functionalized carbon nanotubes (SCNT), two-dimensional (2D) graphene oxide (GO), and three-dimensional (3D) zirconium-based metal-organic frameworks (UiO-66) are self-assembled as filler materials for proton-exchange membranes (PEMs) because of their potential for extending proton transport pathways. Herein, UiO-66-SCNT and UiO-66-SCNT@GO were prepared by a facile solvothermal synthesis and then the nanohybrid chitosan (CS) PEMs were fabricated via solution casting. The hybrid PEMs with higher ion exchange capacity than the pure CS membrane displayed higher proton conductivity and selectivity. The proton conductivity of nanohybrid membrane doped with 7 wt% UiO-66-SCNT@GO (CS/U-S@GO-7) was enhanced to 64 mS cm−1 at 70°C. Simultaneously, the selectivity was reached 19.4 × 104 S s cm−3 and was much higher than the pristine CS membrane (0.13 × 103 S s cm−3). Moreover, the mechanical properties of all composite membranes were significantly enhanced compared with that of the pure CS membrane. The results showed that our research provided a valuable strategy for designing high-performance CS-based PEMs in direct methanol fuel cell (DMFC). Highlights A simple and facile solvothermal synthesis was used to prepare UiO-66-SCNT@GO. UiO-66-SCNT@GO was introduced into chitosan (CS) matrix to optimize proton transport channels. CS-based hybrid membranes exhibit high proton conductivity and selectivity. CS-based hybrid membranes show low methanol permeability.

Preparation and properties of chitosan/acidified attapulgite composite proton exchange membranes for fuel cell applications

AbstractA composite proton exchange membrane chitosan (CS)/attapulgite (ATP) was prepared with the organic–inorganic compounding of ATP and CS. The composite membranes were characterized by scanning electron microscope (SEM), X‐ray diffraction (XRD), and fourier transform infrared spectroscopy (FTIR). The mechanical properties, thermal stability, water uptake, and proton conductivity of the composite membranes were fully investigated. The composite membranes exhibited an enhanced mechanical property, dimensional and thermal stability compared to CS membrane, owing to the interface interaction between ATP and CS. The maximum tensile strength of 53.1 MPa and decomposition temperature of 223.4°C was obtained, respectively. More importantly, the proton conductivity of the composite membrane is also enhanced, the composite membrane with 4 wt% ATP content (CS/ATP‐4) exhibited the highest proton conductivity of 26.2 mS cm−1at 80°C with 100% relative humidity, which is 25.1% higher than pure CS membrane. These results may explore a simple and green strategy to prepare CS‐based PEMs, which have a great potential in the application of proton exchange membrane fuel cells.

Synthesis and investigation of desalinating, antibacterial, and mechanical properties of tetraethylorthosilicate crosslinked chitosan/polyethylene glycol (PEG‐300) membranes for reverse osmosis

ABSTRACTSolution casting method was used to synthesize chitosan (CS)‐based membranes for reverse osmosis (RO) using PEG‐300 and tetraethylorthosilicate as a crosslinker. Their salt rejection (%) and permeate flux (mL/h.m2) was measured by using lab scale RO plant. FTIR spectroscopy reveals interactions between CS and PEG by shifting of OH peak from 3237 cm−1 to lower wavenumber in modified membranes. SEM results showed pores in modified membranes while pure CS membranes had uniform nonporous and dense microstructure. DMA results demonstrated that the addition of PEG lowers the Tg value up to 6.5%. Water content of membranes increases up to 82.63% as the amount of PEG increases owing to its hydrophilic nature. The bacterial killing ability showed that the modified membranes possess good antibacterial activity against Escherichia coli in comparison to the control film. The permeation results revealed that salt rejection and flux of the modified membranes increased up 60% and 86.36 mL/h.m2, respectively. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48870.