Cross-linked Polyethylenimine Research Articles

Efficient removal of Pb(II) and Cd(II) from water by polyethyleneimine-amidated sepiolite-sodium alginate composite microspheres: Characterization and mechanistic analysis

In order to improve the physicochemical properties of heavy metal adsorbents, researchers developed a novel composite microsphere material (SEI) by incorporating Sepiolite (Sep) and cross-linked polyethyleneimine (PEI) with sodium alginate (SA) as a carrier. The stability of the SEI under normal use conditions was high by thermogravimetric analysis, and COOH, OH, and NH2 functional groups were detected by FTIR, which were confirmed to be involved in adsorption. It was found that the adsorption rate of SEI on Pb(II) and Cd(II) obeyed a pseudo-second-order kinetic model, while the adsorption pattern was closely related to the Langmuir equation. Notably, the maximum adsorption capacity of SEI for Pb(II) and Cd(II) was 1099.93 mg/g and 112.89 mg/g, respectively, at 30 °C. In addition, thermodynamic analyses showed that the adsorption process was spontaneous, with entropy increase along with heat absorption. After six adsorption and desorption cycles, the removal of Pb(II) and Cd(II) by SEI remained above 90 %. These findings suggest that SEI is a promising and environmentally friendly material for the removal of Pb(II) and Cd(II).

Tailoring amino-functionalized cellulose separators for improved lithium-ion battery performance

This study aims to enhance cellulose separators for energy storage, focusing on achieving high security and superior electrolyte wetting properties. Bacterial cellulose (BC) separators were initially prepared via vacuum filtration. Subsequently, carboxymethyl cellulose (CMC) underwent amino-functionalization by successfully cross-linking polyethyleneimine (PEI) using glutaraldehyde. The amino-functionalized CMC was then composited onto the BC separator. This composite separator demonstrated excellent thermal stability at 200 °C and favorable electrolyte wetting. The amino groups in PEI enhanced Li+ migration by forming hydrogen bonds with PF6− in the electrolyte. Additionally, molecular-level hydrogen bonding between amino groups on PEI and carboxyl/hydroxyl groups in CMC regulated the separator's porosity. The abundant carboxyl groups in CMC facilitated Li+ transfer, notably boosting the lithium-ion battery's electrochemical performance. After 90 charge and discharge cycles, the discharge capacity of the battery assembled with BC/CMC-PEI composite separator is 132.8 mAh/g, which is 25.1 % higher than the 106.1 mAh/g of the battery assembled with traditional PP separator. At a current density of 2C, the minimum discharge capacity of the battery assembled with the composite separator is 71.1 mAh/g, while the minimum discharge capacity of the battery assembled with the PP separator is 53.6 mAh/g. This approach using functional group modification provides a promising approach to improving the performance of lithium-ion batteries.

GO/MoS2/PEI composite membrane for removin salt ions from water

Separation membranes based on graphene oxide (GO) have attracted much attention due to their good separation properties. But its instability in water and rejection of divalent salt ions is a problem that needs to be solved urgently. In this study, molybdenum disulfide (MoS2) is intercalated into graphene oxide by adding polyethyleneimine (PEI) solution drop by drop for cross-linking, and then GO/MoS2/PEI composite membrane is prepared by vacuum filtration. As MoS2 hydrophobicity increases frictionless water flow channels to improve water flux, PEI cross-linking improves membrane stability and rejection of divalent salt ions. The modified composite membrane has a high rejection of 94.8 % for Mg2+, and water flux is increased by 30 % relative to GO/PEI membrane. In addition, the rejection of the composite membrane to different salt solutions is investigated by MgCl2, MgSO4, NaCl and Na2SO4 solutions, and the results obtained are, in order, R(MgCl2) > R(MgSO4) > R(NaCl) > R(Na2SO4). This modified composite membrane has great potential for salt ion removal.

Biological, anti-inflammatory and antioxidant activity of c-PEI based silica nano composites

In this study, a mixed sol-gel technique using silicate, polyvinyl alcohol (PVA), and polyethyleneimine (PEI) was used to various polymers based on PEI and silica gel. The c-PEI blend co-polymer was synthesized by cross-linking branching PEI in an aqueous solution with PVA. The produced c-PEI particles were highly positively charged and fit inside the range of tens to hundreds of nanometers of silica gel. It has been shown that the prepared c-PEI nanocomposite is a very effective antimicrobial, anti-inflammatory, and antioxidant material. In addition to the appropriate investigation of the anti-inflammatory activity using human red blood cells (HRBCs) stabilization, the developed materials were used to explore antimicrobial activity against yeast (Candida albicans ATCC-10231), Gram-negative bacterial strain (Escherichia coli ATCC-25922), and Aspergillus niger NRRL-3 as a fungus. FTIR, XRD, TEM, TGA, and DSC were among the biological and chemical methods used to characterize the produced c-PEI nanocomposites. The agar diffusion method was used to assess the biological activity of the synthesized compounds, and the results revealed a range in their in vitro-antimicrobial inhibitory activity. Based on the type of pathogenic microbe, the majority of the test substances showed a wide range of activity. The examined substances may be appropriate for the creation of an innovative antibacterial and antifungal medicinal medication.

Iridium Catalyst Immobilized on Crosslinked Polyethyleneimine for Continuous Hydrogen Production Using Formic Acid.

Invited for this month's cover is provided by researchers from National Institute of Advanced Industrial Science and Technology (AIST) in Japan. The image shows the flow type continuous hydrogen production from formic acid and power generation by fuel cell achieved by the iridium catalyst immobilized on crosslinked polyethylene imine. The Research Article itself is available at 10.1002/cssc.202301282.

GSH/pH Dual Activatable Cross-linked and Fluorinated PEI for Cancer Gene Therapy Through Endogenous Iron De-Hijacking and in Situ ROS Amplification.

Ferroptosis-related cancer therapy is limited by insufficient Fe2+ /Fe3+ redox pair and hydrogen peroxide (H2 O2 ) for producing lethal hydroxyl radicals (·OH). Although exogenous iron or ROS-producing drugs can enhance ferroptosis, exploiting endogenous iron (labile iron pool, LIP) stored in ferritin and promoting ROS generation may be safer. Herein, a metal/drug-free nanomedicine is developed for responsive LIP release and H2 O2 generation on the mitochondria membranes, amplifying hydroxyl radical production to enhance ferroptosis-mediated antitumor effects. A glutathione(GSH)/pH dual activatable fluorinated and cross-linked polyethyleneimine (PEI) with dialdehyde polyethylene glycol layer nanocomplex loaded with MTS-KR-SOD (Mitochondria-targeting-sequence-KillerRed-Superoxide Dismutase) and CRISPR/Cas9-CA IX (Carbonic anhydrase IX (CA IX)) plasmids (FP@MC) are developed for enhanced ferroptosis through endogenous iron de-hijacking and in situ ROS amplification. Two plasmids are constructed to knockdown CA IX and translate KillerRed-SOD recombinant protein specifically on mitochondria membranes, respectively. The CA IX knockdown acidifies the intracellular environment, leading the release of LIP from ferritin as a "flare" to initiate endogenous chemodynamic therapy. Meanwhile, MTS-KR-SOD generates H2 O2 when irradiated by a 590nm laser to assist chemodynamic therapy, leading to ROS amplification for mitochondria damage and lipid peroxide accumulation. The combined therapeutic effects aggravate cancer ferroptosis and suppress tumor growth, providing a new paradigm for amplifying ROS and iron ions to promote ferroptosis-related cancer therapy.

Regenerated cellulose/polyethyleneimine composite aerogel for efficient and selective adsorption of anionic dyes

With the requirement of sustainable development in modern society, it is urgent to develop the environmentally friendly adsorbents for selective filtration and separation of toxic dyes from hazardous wastewater. Herein, a stable, reusable, and highly compressible three-dimensional regenerated cellulose/polyethyleneimine composite aerogel (RC/PCA) was successfully prepared directly using cheap cotton pulp as raw material and N-methyl morpholine-N-oxide (NMMO) as the “green” solvent, in which the regenerated cellulose (RC) with hydroxyl groups converted from cotton can interact with polyethyleneimine (PEI) with amine groups. After further crosslinking of RC, PEI and glutaraldehyde (GA), the RC/PCA can be used to selectively absorb anionic dyes from the ternary mixed dye system, which maximal adsorption capacity for methyl orange (MO) can be up to 980.39 mg/g. Moreover, the obtained stable RC/PCA can be repeatedly used at least 50 times for the removal of MO (20 mg/L) with a high filtration efficiency of 99.8 %. The kinetics and isothermal adsorption data were described via the pseudo-second-order kinetic model and Langmuir model. Therefore, this research proposes a novel strategy for developing low-cost, highly efficient, regenerated cellulose-based adsorbents to extract organic dyes from wastewater for potential practical applications.

Shear Stress and ROS Dual-Responsive RBC-Hitchhiking Nanoparticles for Atherosclerosis Therapy.

Atherosclerosis (AS), a leading cause of death worldwide, is a chronic inflammatory disease rich in lipids and reactive oxygen species (ROS) within plaques. Therefore, lowering lipid and ROS levels is effective in treating AS and reducing AS-induced mortality. In this study, an intelligent biomimetic drug delivery system that specifically responded to both shear stress and ROS microenvironment was developed, consisting of red blood cells (RBCs) and cross-linked polyethyleneimine nanoparticles (SA PEI) loaded with a lipid-lowering drug simvastatin acid (SA), and RBCs were self-assembled with SA PEI to obtain biresponsive SA PEI@RBCs for the treatment of AS. SA PEI could achieve sustained release of SA in response to ROS and reduce ROS and lipid levels to achieve the purpose of treating AS. Shear stress model experiments showed that SA PEI@RBCs could respond to the high shear stress level (100 dynes/cm2) at plaques, realizing the desorption and enrichment of SA PEI and improving the therapeutic efficiency of SA PEI@RBCs. In vitro and in vivo experiments have confirmed that SA PEI@RBCs exhibits better in vivo safety and therapeutic efficacy than SA PEI and free SA. Therefore, shaping SA PEI@RBCs into a biomimetic drug delivery system with dual sensitivity to ROS and shear stress is an effective strategy and treatment to facilitate their delivery into plaques.

Graphene quantum dot composite with multiphoton excitation as near infrared-II probe in bioimaging

Non-radiative traps and structures are present on the graphene quantum dots doped with nitrogen and functionalized with amino groups (amino-N-GQDs) and multiple crystalline layers because of cross-link-enhanced emission. Secondary and tertiary amines, which are potential fluorophores, have also been observed on the polyethylenimine (PEI) coating of amino-N-GQDs. Cross-linked PEI coating reduced rotation and vibration, thereby enhancing the photoluminescence quantum yield (PL QY). Introduced nitrogen atoms from N dopants, amino-functionalized groups and PEI, as well as sulfur from polystyrene sulfonate (PSS) enhanced the cooperative effect on the properties of heteroatom-doped materials among electrons captured by new surface states. This enhanced radiative recombination and subsequently enhanced PL QY, therefore, surface conjugation improved the amino-N-GQD surfaces by increasing the quantum confinement of their emissive energy, evidenced by the increased PL QY of amino-N-GQD-PSS-PEI (or amino-N-GQD-polymer composites). In some situations, the maximum available power required for delivery to the two-photon imaging plane without damaging tissues limits imaging depth but the additional brightness provided by amino-N-GQD-polymer composites in this study extended the maximum imaging depth to 240 μm. Amino-N-GQD-polymer composites had favorable two-photon properties under two-photon excitation (self-developed femtosecond Ti–sapphire laser optical system; power: 23.93 nJ pixel−1, 160 scans, approximately 1.09 s of total exposure time; excitation wavelength: 980 nm, near-infrared-II region), indicating that cells treated with amino-N-GQD-polymer composites and the anti-epidermal growth factor receptor antibody can achieve two-photon luminescence with 1/81 of the power required for similar-intensity two-photon autofluorescence (1938.33 nJ pixel−1 with 800 scans, total exposure time of ∼5.44 s). The materials can serve as contrast agents for the non-invasive detection of biological specimens and interior tissues using a two-photon excitation wavelength in the near-infrared region.

Polyethyleneimine (PEI) based thin film nanocomposite (TFN) total heat exchange membranes (THEMs) composed of shaped ZIF-8 crystalline Micro-leaves (ZIF-L)

A novel strategy was developed to build high-performance thin film composite (TFC) total heat exchange membranes (THEMs) by in situ growing ZIF-8 crystalline micro-leaves (ZIF-L) from Polyethyleneimine (PEI) coated on polysulfone (PSF) ultra-filtration substrates. It was found that flexible PEI polymeric chains could tightly cross-link and seal large masses of ZIF-L micro-leaves (ZIF/PEI wt. ratio up to 18.5) to thwart CO2 permeation, on top of PSF substrate. Such PEI cross-linking could also effectively open up the internal channels of ZIF-L micro-leaves to enhance moisture permeance and latent heat recovery without trading off CO2 gas barring property. ZIF-L in varied shapes protruded into the air stream could provide ultra-rough surfaces with increased surface area for improved total energy recovery efficiency. Optimized PEI/ZIF-L TFC THEMs showed ultra-low CO2 permeance of 0.5–8 GPU and ultra-high total heat recovery rates of 68–74%.

Photocatalytic reduction of uranium (VI) by 2D-perylene diimide with surface cross-linked polyethyleneimine

The current energy shortage is a cause for concern and nuclear energy is an important sustainable energy source that is vital to the energy transition. As an important resource for the nuclear industry, uranium is present in large quantities in seawater. However, the efficient extraction of uranium from seawater remains challenging due to low uranium concentrations and biofouling. In this work, 2D-perylene diimide-polyethyleneimine (PDI-PEI) photocatalyst have been successfully synthesised by cross-linking polyethyleneimine on the surface of perylene diimide, which enhanced the extraction of uranium from seawater. An electric field is formed on the surface of the material by photocatalysis, where the positively charged part attracts the negatively charged uranyl group, facilitating the adsorption of uranium to the material. The electrons generated on the surface reduce the adsorbed U(VI) to the insoluble U(IV) and can achieve over 99% removal of uranium in solution. In addition, the PDI-PEI exhibited high antibacterial activity to the bacteria by producing reactive oxygen species. In summary, PDI-PEI have good photocatalytic activity, antimicrobial properties and hydrophilicity, which enhance the ability of the material to extract uranium from seawater and provide a versatile method to enhance uranium adsorption.

Zr4+ and glutaraldehyde cross-linked polyethyleneimine functionalized chitosan composite: Synthesis, characterization, Cr(VI) adsorption performance, mechanism and regeneration

In order to improve the stability, electrostatic interaction and ion exchange ability of chitosan for Cr (VI) removal, it is an effective strategy to introduce polyvalent metal ions and polymers into chitosan molecular chain through crosslinking. In this paper, Zr4+ and glutaraldehyde crosslinked polyethyleneimine functionalized chitosan (CGPZ) composite was successfully synthesized and characterized by XRD, SEM, FTIR, BET, and XPS. The results showed that polyethyleneimine was successfully grafted onto chitosan by Schiff base reaction, while the appearance of ZrO and ZrN bonds verified the successful preparation of CGPZ. The monolayer maximum adsorption capacity of Cr(VI) by CGPZ was 593.72 mg g−1 at 298 K and t = 210 min. The removal efficiency of 100 mg L−1 Cr(VI) reached 95.7 %. The thermodynamic, isotherm and kinetic results show that the adsorption process of Cr (VI) by CGPZ is a spontaneous endothermic process controlled by entropy, which accords with Freundlich model and pseudo-second-order kinetic model. The regeneration experiments show that both HCl and NaOH can effectively desorb Cr(III) and Cr(VI) from the adsorbent surface, and the adsorbent has good acid-base resistance and regeneration performance. The removal of Cr(VI) mainly involves electrostatic attraction, ion exchange, reduction and complexation. CGPZ can synergistically adsorb Cr(VI) by electrostatic interaction of -NH2/-C=N and ion exchange of Cl− ion in the center of Zr, then reduce Cr(VI) to Cr(III) (45.4 % at pH = 2.0) by the -OH group on its surface, and chelate Cr(III) through COO- and -NH- groups.

Preparation of cellulose-based porous adsorption materials derived from corn straw for wastewater purification

Various methods have been used to cope with heavy metal ion contamination in wastewater, which caused serious hazards to ecological and human health. Adsorption is one of the most frequent, economical and effective methods for removing these contaminants. Herein, a porous and amino-rich cellulose-based composite adsorbent (PEI-PCS) with anisotropic property was successfully prepared by covalently cross-linking polyethyleneimine on delignified corn straw. Combined with the porosity of straw substrate and the chelating ability of amino group to metal ions, the as-prepared PEI-PCS exhibited universality (various metal ions), rapid adsorption behavior (within 180 min achieve adsorption equilibrium), high adsorption capacity (85.47 mg g−1 for Cu(II)), and good durability (70 % of adsorption efficiency after 5 cycles). In addition, the adsorption process was conformed to pseudo-second-order dynamics and the Langmuir isotherm models. Lastly, the adsorption mechanism was also elucidated. This study provides a sustainable pathway for the manufacture of efficient biomass-based adsorbents and confirms that functionalized corn straw is a promising material for the treatment of heavy metal ions.

Structural Modifications of Polyethylenimine to Control Drug Loading and Release Characteristics of Amorphous Solid Dispersions.

Crystalline drugs with low solubility have the potential to benefit from delivery in the amorphous form. The polymers used in amorphous solid dispersions (ASDs) influence their maximum drug loading, solubility, dissolution rate, and physical stability. Herein, the influence of hydrophobicity of crosslinked polyethylenimine (PEI) is investigated for the delivery of the BCS class II nonsteroidal anti-inflammatory drug flufenamic acid (ffa). Several synthetic variables for crosslinking PEI with terephthaloyl chloride were manipulated: solvent, crosslinking density, reactant concentration, solution viscosity, reaction temperature, and molecular weight of the hyperbranched polymer. Benzoyl chloride was employed to cap amine groups to increase the hydrophobicity of the crosslinked materials. Amorphous deprotonated ffa was present in all ASDs; however, the increased hydrophobicity and reduced basicity from benzoyl functionalization led to a combination of amorphous deprotonated ffa and amorphous neutral ffa in the materials at high drug loadings (50 and 60 wt %). All ASDs demonstrated enhanced drug delivery in acidic media compared to crystalline ffa. Physical stability testing showed no evidence of crystallization after 29 weeks under various relative humidity conditions. These findings motivate the broadening of polymer classes employed in ASD formation to include polymers with very high functional group concentrations to enable loadings not readily achieved with existing polymers.

Mitigating of Thin-Film Composite PTMSP Membrane Aging by Introduction of Porous Rigid and Soft Branched Polymeric Additives.

This work was focused on the mitigation of physical aging in thin-film composite (TFC) membranes (selective layer ~1 μm) based on polymer intrinsic microporosity (PTMSP) by the introduction of both soft, branched polyethyleneimine (PEI), and rigid, porous aromatic framework PAF-11, polymer additives. Self-standing mixed-matrix membranes of thicknesses in the range of 20-30 μm were also prepared with the same polymer and fillers. Based on 450 days of monitoring, it was observed that the neat PTMSP composite membrane underwent a severe decline of its gas transport properties, and the resultant CO2 permeance was 14% (5.2 m3 (STP)/(m2·h·bar)) from the initial value measured for the freshly cast sample (75 m3 (STP)/(m2·h·bar)). The introduction of branched polyethyleneimine followed by its cross-linking allowed to us to improve the TFC performance maintaining CO2 permeance at the level of 30% comparing with day zero. However, the best results were achieved by the combination of porous, rigid and soft, branched polymeric additives that enabled us to preserve the transport characteristics of TFC membrane as 43% (47 m3 (STP)/(m2·h·bar) after 450 days) from its initial values (110 m3 (STP)/(m2·h·bar)). Experimental data were fitted using the Kohlrausch-Williams-Watts function, and the limiting (equilibrium) values of the CO2 and N2 permeances of the TFC membranes were estimated. The limit value of CO2 permeance for neat PTMSP TFC membrane was found to be 5.2 m3 (STP)/(m2·h·bar), while the value of 34 m3(STP)/(m2·h·bar) or 12,600 GPU was achieved for TFC membrane containing 4 wt% cross-linked PEI, and 30 wt% PAF-11. Based on the N2 adsorption isotherms data, it was calculated that the reduction of the free volume was 1.5-3 times higher in neat PTMSP compared to the modified one. Bearing in mind the pronounced mitigation of physical aging by the introduction of both types of fillers, the developed high-performance membranes have great potential as support for the coating of an ultrathin, selective layer for gas separation.

Polyethylenimine as a Non-Innocent Ligand for Hexacyanoferrates Immobilization

To understand how polyethyleneimine (PEI), as a ligand, affects structure and properties of the transition metals hexacyanoferrates (HCFs) immobilized in cross-linked PEI matrix, we have synthesized Cu(II), Zn(II), and Fe(III) HCFs via successive ion-exchange reactions with metal salts and K4[FeII(CN)6] or K3[FeIII(CN)6]. The structure and properties of the obtained materials in comparison with the crystalline HCF analogs were investigated with FT-IR, Mössbauer, and UV-Vis spectroscopy. Complete reduction of Fe(III) to Fe(II) by PEI in HCF(III) was confirmed. When synthesis was performed at pH favoring binding of precursor metal ions by PEI, cyano-bridged hybrids rather than polymer-HCFs composites were formed. Although the obtained hybrids did not demonstrate sorption activity toward cesium ions, known for crystalline HCFs, they are of interest for the other applications. SQUID measurements revealed a significant difference in magnetic properties of PEI-HCFs hybrids in comparison with crystalline HCFs. Due to the Fe(III) to Fe(II) reduction in HCF ions, Cu(II) and Fe(III) HCFs(III) lost the molecular magnets properties in PEI matrix, but magnetic ordering, including ferromagnet-antiferromagnet interactions, was observed in all hybrids over the broad temperature range.

Aminated waste paper membrane for efficient and rapid filtration of anionic dyes and antibiotics from water

Remediation of wastewater with solid waste-based adsorbents is of great environmental significance, but most current waste-based adsorbents suffer from low efficiency. In this work, aminated waste paper (WP-NH2) membrane is successfully prepared by oxidation of various types of waste paper followed by grafting and crosslinking polyethyleneimine (PEI). WP-NH2 shows extremely high adsorption for various anionic dyes and antibiotics. Specifically, the adsorption amount for methyl orange (MO) and tetracycline (Tc) are 2156.2 mg·g−1 and 253.7 mg·g−1, respectively. WP-NH2 is stable enough to be regenerated several times and still maintains high adsorption efficiency. Mechanistic studies show that the adsorption toward anionic MO is mainly through electrostatic interaction and hydrogen bonding, and the adsorption of antibiotic Tc relies on hydrogen bonding and Lewis acid-base reaction. Grafting PEI on the fiber surface enables efficient exposure of adsorption sites. Therefore, WP-NH2 membrane can quickly, continuously and efficiently filter out MO and Tc from water. After 5800 L·m−2 MO and 3150 L·m−2 Tc filtration, the interception rate of the two contaminants is still higher than 90 %. Moreover, WP-NH2 shows high selectivity and can be used for efficient separation of dye mixture. These results reveal that this advanced adsorbent made from waste paper has great potential application in industrial dye and antibiotic wastewater remediation.

One-Step Synthesis of 3D Pore-Structured Adsorbent by Cross-Linked PEI and Graphene Oxide Sheets and Its Application in CO2 Adsorption.

In this study, a one-step method of polyethylenimine (PEI) cross-linking graphene oxide (GO) was used to prepare a 3D pore-structured adsorbent with abundant amine groups for chemisorption of CO2. The cross-linking of PEI with GO sheets and the vacuum freeze-drying step are the keys to the formation of the 3D pore structure. The results of characterization analysis revealed that the as-prepared adsorbent had a 3D porous structure rich in amine groups. Besides, the adsorption/desorption test showed that the prepared adsorbent has excellent and stable adsorption performance, and the maximum CO2 adsorption capacity is 2.18 mmol/g at 343 K and 10 vol % CO2. Moreover, the adsorption kinetics analysis indicated that the adsorption process was dominated by homogeneous adsorption, and the adsorbent had a strong affinity with CO2. Finally, the correlation analysis shows that the kinetic constants obtained by the Avrami model simulation can be effectively used for the actual CO2 adsorption process design.

Polyethyleneimine-polyvinylchloride-based crosslinked membranes for use in PEM water electrolysis operating above 100 °C

Water electrolysis is the most promising method to produce non-fossil fuel derived H2. The medium temperature (100–350 °C) water (steam) electrolysis is highly promising technology because it can not only reduce energy consumption but also utilize the low-grade waste heat. However, it is challenged by the proton conductive membrane performance. Herein, polyvinyl chloride (PVC) - polyethyleneimine (PEI) hybrid membrane was realized by a simple cross-linking of PVC and PEI. The intercalated nitrogen-containing groups of PEI promote the adsorption and loading rate of phosphoric acid, which offers the proton conductivity for hybrid membrane. The optimized PVC-PEI with content ratio of 1:4 exhibits a maximum proton conductivity of 4.3 × 10−2 S cm−1 at 180 °C and a long-term conductivity stability for 200 h at 140 °C. The PVC-PEI membrane electrode assembly with commercial IrO2 anode and Pt/C cathode posts high water electrolysis reactivity in the range of 100–180 °C and reliable stability for the water electrolysis at 140 °C.

Isotherm and Kinetic Studies on the Adsorption Behavior of Metanil Yellow Dyes onto Modified Shrimp Shell-Polyethylenimine (SS-PEI)

The present study investigated the ability of modified shrimp shell by Polyethylenimine (PEI) for enhanced removal of metanil yellow. The modification was carried out using citric acid as a cross linker. The removal of metanil yellow by modified shrimp shell-PEI was conducted by batch method and investigated some parameters affected adsorption including pH, initial dye concentration, and contact time. The optimum conditions were achieved at pH 5, initial dye concentration 1200 mg/L, and contact time 90 minutes. The adsorption isotherm study showed that the adsorption of metanil yellow dye by modified shrimp shell-PEI followed the Langmuir isotherm model with a maximum adsorption capacity (qm) 121.951 mg/g. The kinetic study indicated that the adsorption process suited to the pseudo-second-order model. The characterization results revealed the differences in the adsorbent characteristics before and after the adsorption of metanil yellow dye. The cross-linked PEI onto shrimp shell provided more active sites (amine groups) to bind dye molecules. It can be concluded that modified shrimp shell by PEI has increased its ability in metanil yellow removal.