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The present study reported the synthesis of novel organic–inorganic hybrid nanocomposite by incorporating tin (IV) based ion exchanger into the hybrid polymer network of chitosan and gelatin prepared under vacuum for the efficient removal of heavy metal ions and toxic dyes from an aqueous fluid. The physicochemical studies such as ion exchange capacity (IEC), chemical stability, thermal stability, pH titration and distribution behaviour studies were also carried out to determine the cation exchange behaviour of the material. The surface morphology and structural properties were studied by the techniques such as FTIR, FESEM, EDS, TEM and XRD. Distribution studies confirmed the synthesized CG/STPNC had the highest selectivity for Pb2+ ions (85.3 mL/g). Maximum adsorption of methylene blue (82%) was achieved within 240 min at 500 mg of adsorbent dose, 10 mg/L of the initial concentration of dye, pH of 7 and 30 °C of temperature. Adsorption kinetic data fitted well with pseudo-second order rate model with R2 = 0.995. The correlation value 0.95 and favourable RL = 0.21 of adsorption data suggested better fit for Langmuir adsorption. Thus the synthesized nanocomposite ion exchanger was found to be a promising cation exchanger as well as an adsorbent for heavy metal ion and dye removal from textile industrial effluents.Graphical abstract

Anion exchange membrane (AEM) electrolysis is one of the most promising water electrolysis technologies, combining the advantages of proton exchange membrane (PEM) electrolysis, such as high gas purity, high current densities and dynamic operation, while using cheap transition metal electrocatalysts known from alkaline water electrolysis (AWE). AEM water electrolysis (AEMWE), when operated liquid (electrolyte or water) free (dry) at the cathode side, offers simplified water management, reducing the balance‐of‐plant. Numerous factors, such as cell design, membrane properties, flow rate of electrolyte and operation parameters, directly or indirectly, impact the performance of AEMWE, which becomes even more vital when the cathode compartment is operated liquid free. Herein, this work presents a comprehensive overview of several factors involved in the performance of a dry cathode AEMWE. Advancements and challenges in membrane materials, asymmetric electrolyte feeds and operating parameters were analysed. Finally, to have a durable and efficient AEMWE, this article discusses current development on the dry cathode AEMWE technology and outlines prospective avenues for further improving the system.

Ion exchange polymers were used for mercury and lead ions removal in water. The heavy metal ion concentration was analyzed by two independent methods: inductively coupled plasma–optical emission spectroscopy (ICP-OES) and gravimetry. The studied cation exchange polymer (CEP) was sulfonated poly(ether ether ketone) (SPEEK), and the anion exchange polymer (AEP) was poly(sulfone trimethylammonium) chloride (PSU-TMA). The removal capacity was connected with the ion exchange capacity (IEC) equal to 1.6 meq/g for both polymers. The concentration ranges were 0.15–0.006 mM for Hg 2+ and 10.8–1.0 mM for Pb 2+ . SPEEK achieved 100% removal efficiency for mercury and lead if the concentration was below the maximum sorption capacity ( Q max ), which was about 210 mg/g for Pb 2+ with SPEEK. For PSU-TMA, the surprising removal efficiency of 100% for Hg 2+ , which seemed incompatible with ion exchange, was related to the formation of very stable complex anions that can be sorbed by an AEP. Langmuir adsorption theory was applied for the thermodynamic description of lead removal by SPEEK. A second-order law was effective to describe the kinetics of the process.

The strongly acidic sulfonated crosslinked polystyrene cation-exchange resins employing divinylnaphthalene or divinylbiphenyl as the crosslinking reagent have been prepared. Their properties in terms of the production of bisphenol-A from phenol and acetone were examined in comparison with the corresponding resin consisting of divinylbenzene. It has been found out that the high conversion of acetone can be obtained even after 150 days of reaction time, which is mainly due to the large space inside the structure of the resins developed here.

Chemical grafting of low-density polyethylene film blended with ethylene propylene diene monomer rubber (PE/EPDM) using styrene monomer followed by a sulfonation process was investigated. Different factors affecting the grafting process, such as monomer and initiator concentrations, time of reaction, and grafting temperature, were studied. Sulfonation of the grafted films was carried out using chlorosulfonic acid in dichloromethane. Characterization of the grafted and sulfonated films was performed using ATR-FTIR, SEM, TGA, and XRD instruments. The grafting was successfully performed in aqueous media using sodium bisulfite as initiator, reaching a grafting yield of 130% and an ion exchange capacity of 1.2 m eq /g. The removal of thorium ions from aqueous solution was studied using the obtained ion exchange films. The results showed that the maximum adsorption capacity of Th(IV) was 177.5 mg. g −1 (pH = 3, 298 K and 60 min). Removal isotherm and Kinetics were investigated, and the results revealed that the adsorption process was chemisorption homogeneous monolayer adsorption, exothermic, and spontaneous.

The nanocomposite membranes consisting of polyvinylidene fluoride (PVDF) and graphene oxide (GO) are prepared via solution casting method and the membranes are subsequently sulfonated by chlorosulfonic acid. A series of physicochemical properties such as, thermogravimetric analysis (TGA), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) are carried out to investigate the thermal and structural properties of the prepared sulfonated PVDF GO (SPG) nanocomposite membranes. The preliminary studies including ion exchange capacity (IEC), water and methanol absorption are conducted for evaluating the feasibility of the SPG membranes to perform as a proton exchange membrane (PEM). The results are quite encouraging and acceptable for further investigations on membrane performance evaluation. The proton conductivity of the membrane has been remarkably improved after the sulfonation and found to be 0.075 S cm−1 at 25 °C which can be ascribed to the hydrophilic nature of incorporated graphene oxide nanoparticles as well as sulfonic groups attached to the PVDF chains which forms a suitable proton conduction channel and favors easy proton migration. Further, the blocking effect of GO provides an advantage for the methanol permeation rate thereby creating a torturous path and giving the methanol permeability value as 1.62 × 10–6 cm2s−1 which is 76.62% less than Nafion 117 membrane. Finally, the higher selectivity of the SPG membranes makes them more competitive than Nafion 117 membranes to employ as a PEM for DMFC.

Zeolite X powder was synthesized using natural low-grade diatomite as the main source of Si but only as a partial source of Al via a simple and green hydrothermal method. The microstructure and surface properties of the obtained samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), wavelength dispersive X-ray fluorescence (XRF), calcium ion exchange capacity (CEC), thermogravimetric-differential thermal (TG-DTA) analysis, and N2 adsorption-desorption technique. The influence of various synthesis factors, including aging time and temperature, crystallization time and temperature, Na2O/SiO2 and H2O/Na2O ratio on the CEC of zeolite, were systematically investigated. The as-synthesized zeolite X with binary meso-microporous structure possessed remarkable thermal stability, high calcium ion exchange capacity of 248 mg/g and large surface area of 453 m2/g. In addition, the calcium ion exchange capacity of zeolite X was found to be mainly determined by the crystallization degree. In conclusion, the synthesized zeolite X using diatomite as a cost-effective raw material in this study has great potential for industrial application such as catalyst support and adsorbent.

A series of nanocomposites based on quaternized polyvinyl alcohol (PVA) and nanocellulose (NC) from oil palm empty fruit bunch have been used as anion exchange membranes (AEM) for direct alcohol-hydrogen peroxide fuel cell (DAHPFC) applications. The PVA and NC are individually quaternized with hexadecyltrimethyl ammonium bromide (HDT) and glycidyltrimethyl ammonium chloride (GAC), cross-linked, and cast to form quaternized polyvinyl alcohol/quaternized nanocellulose (QPVA/QNC) membranes following thermal treatment. We observe that an increase of QNC quaternization degree increases quaternary ammonium content and the dimensional stability of the QPVA/QNC membranes while inhibiting PVA matrix crystallinity, decreasing both HDT dispersal and membrane thermal stability. We determine that QPVA/QNCGAC30% membranes exhibit a maximum ion conductivity of 9.85 ± 0.07 mS/cm at room temperature and 29.07 ± 1.76 mS/cm at 80 °C with an ion exchange capacity of approximately 1.14 meq/g. Addition of QNC also enhances the alkaline stability of the optimized QPVA/QNC membrane with less ion conductivity loss. Optimized QPVA/QNC membranes have been demonstrated as an AEM in DAHPFCs without the use of platinum based catalysts. Compared with other membranes, we believe this nanocomposite membrane with comparable performances can promise AEM application in DAHPFCs.

Highlights Ultrahigh-Density 1D Ionic Wire Arrays. A high density (~10 12 cm −2 ) of 1D ionic channels is achieved via self-assembly of a homopolymer, enabling simultaneous high ion selectivity and conductivity for efficient osmotic energy conversion. Anti-Swelling Membrane with Superior Performance. The membrane exhibits an ultrahigh ion-exchange capacity (~2.69 meq g −1 ) yet minimal swelling (<10%) due to hydrophobic alkyl shell protection, leading to a breakthrough power density of 40.5 W m⁻² under a 500-fold salinity gradient. Multifunctional Design with Antibacterial Properties. The imidazole-functionalized membrane not only enhances osmotic energy harvesting but also provides excellent antibacterial performance, offering a novel strategy for advanced separation membranes. Osmotic energy, existing between the seawater and river water, is a renewable energy source, which can be directly converted into electricity by ion-exchange membranes (IEM). In traditional IEMs, the ion transport channels are formed by nanophase separation of hydrophilic ion carriers and hydrophobic segments. It is difficult to realize high-density ion channels with controlled spatial arrangement and length scale of ion carriers. Herein, we construct high-density 1D ion wires as transmission channels. Through molecular design, hydrophilic imidazole groups and hydrophobic alkyl tails were introduced into the repeat units, which self-assembled into 1D ion transporting core and protecting shell along the main chains. The areal density of the ionic wire arrays is up to ~ 10 12  cm −2 , which is the highest value. The ionic wires ensure both high ion flux transport and high selectivity, achieving an ultrahigh-power density of 40.5 W m −2 at a 500-fold salinity gradient. Besides, the ionic wire array membrane is well recyclable and antibacterial. The ionic wires provide novel concept for next generation of high-performance membranes.

Silicon carbide (SiC) was pretreated and functionalized by using α, ω-diaminopropyl polydimethylsiloxane (PDMS) to obtain a novel inorganic filler SiC (PDMS). Then, a series of branched sulfonated polyimide/SiC (PDMS) (bSPI/SiC (PDMS)) composite membranes with different contents of SiC (PDMS) were fabricated for vanadium redox flow battery (VRFB) application. Fourier transform infrared spectra, X-ray diffraction, and field emission scanning electron microscope demonstrate the successful preparation of SiC (PDMS) and bSPI/SiC (PDMS) membranes. The thermogravimetric analysis shows that bSPI/SiC (PDMS)-1.5% membrane has better thermal stability than pure bSPI, bSPI/SiC-1.5%, and Nafion 117 membranes. The ex situ chemical stability test results show that bSPI/SiC (PDMS)-0.5–2.5% composite membranes have better chemical stabilities than pure bSPI membrane. The physicochemical properties of bSPI/SiC (PDMS) membranes, including water uptake, swelling ratio, ion exchange capacity are investigated. Thereinto, bSPI/SiC (PDMS)-1.5% membrane has the highest proton selectivity ( S : 2.99 × 10 5  S min cm −3 ) and was chosen as an optimum VRFB membrane. And the VRFB assembled with bSPI/SiC (PDMS)-1.5% membrane exhibits better battery performance than that assembled with Nafion 117 membrane during 500-time cyclic charge–discharge test at 20–60 mA cm −2 . Above results indicate that as-optimized bSPI/SiC (PDMS)-1.5% membrane has great potential for VRFB application.