Adsorption Of Polyethyleneimine Research Articles

DISPERSION OF AQUEOUS Y2O3 NANO-SUSPENSION AND FABRICATION OF TRANSPARENT CERAMICS BY COLLOIDAL PROCESSING

In the present study, transparent Y2O3 ceramics were successfully fabricated via colloidal processing, employing polyethylenimine (PEI) as an effective dispersant. The effect of PEI on nanosized Y2O3 suspensions was characterized by zeta-potential, adsorption behavior, rheological properties, and sedimentation test. The addition of PEI shifted the IEP of the Y2O3 powder towards a more alkaline pH range, and the adsorption of PEI on the Y2O3 surfaces gradually increased with the amount of PEI until reaching the saturation adsorption at 1.5 w/%. The PEI amount of 1.5 w/% was superior for the preparation of Y2O3 suspension as a result of a lower viscosity or sedimentation behavior. The viscosity of the suspension depended on the solids loading, increasing with the amount of powder. The optimal rheological behavior was achieved with 29 /% Y2O3 in the suspension, enabling the centrifugal slip casting of complex-shaped green bodies with a packing density of 43 %. Including an additional CIP treatment boosted the packing density of the green compacts, achieving above 50 %. Vacuum sintering the compacts at 1700 °C for 5 h yielded high-density ceramics exhibiting an in-line transmittance of approximately 73 % at a wavelength of 1100 nm.

Influence of Polyethylenimine (PEI) in enhancement of microstructure and surface morphology of recycled construction and demolition waste aggregate in concrete by carbonation

This investigation explores the influence of Polyethylenimine (PEI) on the improvement of carbon dioxide (CO2) uptake, surface texture, and pore structure of construction and demolition waste (CDW) through carbonation. The study focuses on the coarser fraction of CDW (10 mm), which is pre-treated with varying concentrations of PEI before being carbonated. The resulting changes in pore structure, mineralogical composition, physical properties, and surface morphologies of the CDW are characterized using various techniques. The study also evaluates the impact of carbonated CDW on compressive strength. The results indicate that PEI modification of CDW enhances carbonation efficiency by reducing pores more effectively than non-treated CDW. This microstructural refinement is possible due to the formation of calcite and its products, facilitated by PEI adsorption into CDW, enhanced CO2 uptake, and formation of calcite products through carbonation. Additionally, PEI modification results in the formation of undulated plate-like structures that enhance surface morphology and compressive strength when used in concrete. The carbonation behavior of PEI-modified CDW in concrete was also investigated by analyzing carbonation depth and pH value. The results reveal that the optimal PEI concentration for enhancing the performance of CDW is 0.2. Overall, the study highlights the potential of PEI modification as an effective approach to improve the properties of CDW and its potential as a sustainable construction material.

Temperature controlled adsorption of polyethyleneimine on the sepiolite surface

The effects of temperature (15, 25 and 35 °C) on the adsorption properties of polyethyleneimine (PEI) on the sepiolite (Sep) surface and some properties of the Sep/PEI suspensions including their stability were studied. It was shown that the increase in temperature caused larger adsorption of PEI macromolecules on the Sep surface, which was the effect of the spacious PEI conformation at higher temperatures. Stability of the Sep/PEI suspension was also better when temperature was higher due to effective electrosteric stabilization. The obtained results indicate how the temperature influences the textural and electrokinetic properties of the Sep/PEI systems. The following analytical methods: UV–Vis spectrophotometry, XRD, nitrogen adsorption-desorption method, elemental analysis, SEM-EDX, FT-IR, TG-DSC, viscometry and zeta potential measurements were used in the performed research. The presented findings can be successfully used to create hybrid materials dedicated to water and wastewater treatment as well as in the gas capture processes.

Plasmonic Dual-Gap Nanodumbbells for Label-Free On-Particle Raman DNA Assays.

Metal nanostructures with a tunable plasmonic gap are useful for photonics, surface-enhanced spectroscopy, biosensing, and bioimaging applications. The use of these structures as chemical and biological sensing/imaging probes typically requires an ultra-precise synthesis of the targeted nanostructure in a high yield,with Raman dye-labeling and complex assay components and procedures. Here, a plasmonic nanostructure with tunable dual nanogaps, Au dual-gap nanodumbbells (AuDGNs), is designed and synthesizedvia the anisotropic adsorption of polyethyleneimine on Au nanorods to facilitate tip-selective Au growths on nanorod tips for forming mushroom-shaped dumbbell-head structures at both tips and results in dual gaps (intra-head and inter-head gaps) within a single particle. AuDGNs are synthesized in a high yield (>90%) while controlling the inter-head gap size, and the average surface-enhanced Raman scattering (SERS) enhancement factor (EF) value is 7.5×108 with a very narrow EF distribution from 1.5×108 to 1.5×109 for >90% of analyzed particles. Importantly, AuDGNs enable label-free on-particle SERS detection assays through the diffusion of target molecules into the intraparticle gap for different DNA sequences with varying ATGC combinations in a highly specific and sensitive manner without a need for Raman dyes.

Effective melanoidin adsorption of polyethyleneimine- functionalised molasses-based porous carbon: Adsorption behaviours and microscopic mechanisms

Sugar industry is an integral part of the food and agriculture sector of the national economy. Cane juice decolourisation is a crucial process in sugar production that directly impacts the final colour value of the sugar. However, the chemicals used in traditional methods may be harmful for food safety. Thus, advanced and effective alternatives methods should be developed to further address the problems on sugar production and quality. In this study, polyethyleneimine-functionalised molasses-based porous carbon (PMPC) was prepared from cane molasses, and was reversely applied to remove melanoidins from cane juice. The melanoidin removal efficiency by PMPC was 91.66% with the adsorption capacity of 550.00 mg/g in the adsorption equilibrium state. From the adsorption thermodynamics analysis, the adsorption process of melanoidins onto PMPC was spontaneous and endothermic. Analysis of the interaction mechanisms demonstrated that the successful adsorption of melanoidins by PMPC was mainly achieved through the electrostatic interations and other weak interactions (hydron-bond interaction), and a melanoidin molecule can be bonded with three to four protonated amine groups of PMPC. In addition, the mass transfer behaviour of the melanoidins adsorbed onto PMPC was determined using the mixed model of external and internal diffusion resistance, and the active-onto-site adsorption model. The results showed the melanoidins adsorbed by PMPC was a multilayer adsorption process dominated by chemisorption. Therefore, PMPC was proved to be an ideal adsorbent for cane juice decolourisation, with the advantages of green, high efficiency, and recyclability.

The pH as a tool to tailor the performance of symmetric and asymmetric layer-by-layer nanofiltration membranes

Layer-by-layer assembly of polyelectrolyte layers is a versatile method to produce nanofiltration membranes. The membrane formation and subsequently performance is easily tailored with pH as it varies the polyelectrolyte charge density. Here, membranes are fabricated at different pH (4,8, and 9) with branched polyethyleneimine (PEI)/poly(sodium-4-styrenesulfonate) (PSS) layers (symmetric membranes) or a combination of poly(diallyldimethylammonium chloride) (PDADMAC)/PSS base layers terminated with PEI/PSS layers (asymmetric membranes).Overall, increasing the pH lowers the PEI charge density, which increases PEI adsorption, as measured by optical reflectometry and positive zeta potential. For symmetric systems, decreasing the charge density decreases the salt retention, because fewer intrinsic linkages are formed. Contrarily, asymmetric membranes, independent of charge density, show retentions >90% for MgSO4 and Na2SO4.Additionally, the benefit of asymmetric membrane formation is proven by comparing the best membrane performances. Asymmetric membranes prepared at pH = 4 form an open base layer and defect-free dense selective layer, resulting in much higher permeabilities compared to symmetric membranes (∼13 and ∼9 L/(m2hbar)), and significantly improving MgSO4 and Na2SO4 retentions (>95% compared to >90%).By combining two well-known polycations and tailoring the pH, versatile membranes are produced, without the need for synthesis or modification steps while obtaining improved water fluxes and salt retentions.

Adsorption and conformation of polyethylene imine on the SiC/water interface and effects on the dispersion stability of slurry

The adsorption of polyethylene imine (PEI) on the SiC/water interface was studied in details by adsorption isotherms and kinetics. The adsorption results indicated that PEI formed saturated monolayer coverage on the SiC surface and the adsorption reached the equilibrium within 30 min. Langmuir and pseudo-second-order models could better describe the adsorption process. The adsorption was mainly dominated by electrostatic interaction between positively charged PEI and negatively charged SiC surface. With the pH increasing from 5 to 8, the conformation of PEI on the SiC surface transformed from flat trains to loops and tails, and then the PEI adsorption capacity increased gradually so that the contact angles of modified SiC decreased from 20.9° to 13.7°, the maximum values of zeta potential increased from 37.1 to 43.9 mV and the maximum stability of modified SiC suspensions at pH 5 also enhanced. Moreover, modified SiC powder with the best dispersion was obtained with 0.5 wt% PEI at pH 6.5 and modified slurry had the low viscosity of 664 mPa·s at high solid loading of 55 vol%.

Adsorption of Polyethyleneimine on Fine Arsenopyrite and the Effect on Its Xanthate Flotation

Effective flotation of fine particles is a problem for mineral processing. In this paper, a flocculant mostly used in heavy metal ion treatment was used in an arsenopyrite flotation system. The adsorption behavior and flotation performance of PEI on the xanthate flotation of arsenopyrite were investigated through zeta potential and adsorbed amount measurements, XPS and size distribution detections, and micro-flotation tests. Zeta potential results showed that the adsorption of 40 mg/L polyethyleneimine (PEI) caused an increase in the zeta potential of arsenopyrite, and had only a slight depression on the further adsorption of SBX, which was further confirmed by the results of the adsorbed amount measurements. However, when the dosage of PEI was 150 mg/L, the adsorption of SBX was strongly depressed. This was because moderate PEI only bridged different arsenopyrite particles, and most of the active sites for the SBX adsorption were still exposed; when PEI was in excess, the mineral particles would be covered so that there were not enough active sites for SBX adsorption. Fe and As on the mineral surface were the adsorption sites for the PEI molecules, which were resolved from the chemical shifts in the As/Fe peaks of the XPS spectra. PEI can increase particle size, and moderate PEI dosage can make the particle size suitable for flotation with SBX where bridging and hydrophobic effects take place. The flotation results showed that −20 μm arsenopyrite particles had poor flotation recovery with the SBX collector alone, but when they were treated with 40 mg/L PEI, the recovery largely increased. PEI can serve as an effective flocculant for the flocculation flotation of fine arsenopyrite. A comparison model, showing the possible interactions among reagents, particles, and bubbles in the pulp with different PEI dosages, is proposed.

Nonaqueous gel casting using multicomponent concentrated slurries through Michael additive reaction for fabricating silicon nitride dense ceramics

A novel gel casting system using nonaqueous, multicomponent, and concentrated slurries was designed for manufacturing Si3N4 dense ceramics with complex structures. The proposed process involves the dispersion of reagent particles in α-terpineol aided by the saturated adsorption of polyethyleneimine partially complexed with oleic acid (PEI-OA) as well as the addition of small amounts of multifunctional acrylates (MAs). The occurrence of the Michael additive reaction between the MAs and the remaining amines of PEI-OA fixed on the reagent particles resulted in a gradual increase in the viscosity of the slurry until its solidification. Using the Si3N4/α-terpineol slurry as a model system, the effects of processing parameters such as OA complex ratio, particle volume fraction, and MA structures on the solidification behaviors were systematically investigated. A slurry having higher particle concentration which was treated with PEI-OA comprised from lesser OA ratio found to effectively solidify within 2 h when mixed with MA having larger number of acryloyl group per molecule. The proposed gel casting process was then applied to the multicomponent Si3N4–Y2O3–Al2O3–TiO2–AlN/α-terpineol system. The gel casted complex structured green compacts were successfully densified up to 98% by liquid phase sintering at 1750 °C under 0.9 MPa N2 gas pressure.

Monolayer transition-metal dichalcogenides with polyethyleneimine adsorption

Monolayer transition-metal dichalcogenides MX2 (M = Mo, W; X = S, Se, Te) have attracted much attention for use in electronic and optical applications. Due to their sensitivity to gases, the surface of these materials has been protected by coating with polymers such as polyethyleneimine (PEI). However, the effects of such coating layers on the electronic and optical properties of MX2 are not well understood. In this work, density functional theory calculations are used to study the effects of adsorption of PEI on monolayer MX2 substrates based on the electronic and optical properties before and after PEI adsorption. The results show that the bandgap of the substrate decreases significantly upon PEI adsorption, while the optical spectra show only slight modification with a decrease of intensity at short wavelengths around 300 nm. The results also indicate that PEI adsorption results in n-type doping states in MX2 but does not deteriorate the optical properties in the visible range.

Probing the Molecular Structure of Coadsorbed Polyethylenimine and Charged Surfactants at the Nanoemulsion Droplet Surface.

Nanoemulsions, nanoscale oil droplets dispersed in an aqueous medium, can be stabilized by polymer-surfactant (PS) mixtures, making them ubiquitous in commercial, industrial, and pharmaceutical applications. It is well-known that the presence of PS layers coadsorbed at the droplet surface plays a significant role in droplet stability and functionality; however, little is understood about the molecular nature of this coadsorption. Such insights are especially important for application in drug delivery where physiological conditions can vary the environmental pH and significantly impact stabilization. Hence, the focus of this study examines the surface properties of ∼300 nm nanoemulsions stabilized by the coadsorption of polyethylenimine (PEI) and charged alkyl surfactants sodium dodecyl sulfate (SDS) and dodecyltrimethylammonium bromide (DTAB). PEI is a common charge-tunable polymer used in nanocarrier templates. This study employs vibrational sum frequency scattering spectroscopy, coupled with ζ-potential and surface pressure measurements performed as a function of varying concentrations and pH. The surface specific spectroscopic results reported herein reveal that PEI adsorption and molecular ordering is influenced by both electrostatic and hydrophobic interactions. While the degree of PEI adsorption is stronger in the presence of anionic SDS than cationic DTAB, for both surfactants, PEI is molecularly disordered in acidic conditions and adopts a persistent net ordering as the solution pH becomes more basic. Both surfactants also display degrees of interfacial conformational ordering that is altered by the presence of the coadsorbed polymer. These results demonstrate the molecular-level diversity in PEI behavior at the droplet interface and provide insight into how such behavior can be controlled to yield nanocarrier technology with specific functions and enhanced efficacy.

Electrochemical and thermodynamic study on the corrosion performance of API X120 steel in 3.5% NaCl solution

The present work studied the effect of temperature on the corrosion behavior of API X120 steel in a saline solution saturated with CO2 in absence and presence of polyethyleneimine (PEI) as an environmentally safe green inhibitor. The effect of PEI on the corrosion behavior of API X120 steel was investigated using destructive and non-destructive electrochemical techniques. The overall results revealed that PEI significantly decreases the corrosion rate of API X120 steel with inhibition efficiency of 94% at a concentration of 100 μmol L−1. The adsorption isotherm, activation energy and the thermodynamic parameters were deduced from the electrochemical results. It is revealed that the adsorption of PEI on API X120 steel surface follows Langmuir adsorption isotherm adopting a Physi-chemisorption mechanism. Finally, the samples were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques to elucidate the effect of aggressiveness of corrosive media on the surface morphology and the corrosion performance of API X120 steel. The surface topography result indicates that the API X120 steel interface in PEI presence is smoother than CO2 with Cl− ions or Cl− ions only. This is attributed to the compact protective film limits the aggressive ions transfer towards the metallic surface and reduces the corrosion rate. Moreover, PEI inhibition mechanism is based on its CO2 capturing ability and the PEI adsorption on the steel surface beside the siderite layer which give the PEI molecules the ability to reduce the scale formation and increase the corrosion protection due to capturing the CO2 from the brine solution.

Electronic and optical properties of monolayer MoS2 under the influence of polyethyleneimine adsorption and pressure.

MoS2 is one of the well-known transition metal dichalcogenides. The moderate bandgap of monolayer MoS2 is fascinating for the new generation of optoelectronic devices. Unfortunately, MoS2 is sensitive to gases in the environment causing its original electronic properties to be modified unexpectedly. This problem has been solved by coating MoS2 with polymers such as polyethyleneimine (PEI). Furthermore, the application of pressure is also an effective method to modify the physical properties of MoS2. However, the effects of polyethyleneimine and pressure on the electronic and optical properties of monolayer MoS2 remain unknown. Therefore, we elucidated this matter by using density functional theory calculations. The results showed that the adsorption of the PEI molecule significantly reduces the width of the direct bandgap of the monolayer MoS2 to 0.55 eV because of the occurrence of the new energy levels in the bandgap region due to the contribution of the N-2pz state of the PEI molecule. Remarkably, the transition from semiconductor to metal of the monolayer MoS2 and the MoS2/PEI system occurs at the tensile pressure of 24.95 and 21.79 GPa, respectively. The bandgap of these systems approaches 0 eV at the corresponding pressures. Importantly, new peaks in the optical spectrum of the clean MoS2 and MoS2/PEI appear in the ultraviolet region under compressive pressures and the infrared region under tensile strains.

Polyethylenimine-Grafted HKUST-Type MOF/PolyHIPE Porous Composites (PEI@PGD-H) as Highly Efficient CO2 Adsorbents

Searching for highly efficient and robust CO2 adsorbents is very important for CO2 capture, utilization, and storage. In this study, new polyethylenimine-grafted metal–organic framework (MOF)–polymer composites, abbreviated as PEI@PGD-H, were synthesized via high internal phase emulsion (HIPE) template polymerization of divinylbenzene and glycidyl methacrylate, followed by in situ generation of HKUST-type MOF in the presence of hydrophobic-modified CuO nanoparticles via the reaction of CuO with 1,3,5-benzenetricarboxylic acid and then polyethylenimine (PEI) functionalization via epoxy–amine reaction and amine–metal sites interaction. The coexistence of the hierarchical interconnected porous skeleton of poly(glycidyl methacrylate–divinylbenzene) (PGD), high specific surface area of MOF, and chemical CO2 adsorption of PEI endows PEI@PGD-H with high CO2 adsorption capacity, rate, and selectivity. PEI70@PGD-H shows a CO2/N2 separation factor as high as 76 and CO2 adsorption capacities of 4.3, 3.0, and 1.8 mmo...

CO2 Adsorption on Premodified Li/Al Hydrotalcite Impregnated with Polyethylenimine

In this study, Li/Al hydrotalcite (HT) was treated with calcination and potassium hydroxyl-ethanol to form bcHT (basic-modified calcined hydrotalcite). This material was then polyethylenimine (PEI)-functionalized to create a new sorbent that has ultralow energy consumption. Various methods were applied to characterize the sorbent, including N2 adsorption–desorption, Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. CO2 adsorption capacity, which was affected by PEI loadings and adsorption temperatures, was assessed with the CO2 adsorption isotherms and cyclic CO2 adsorption–desorption performance. Results showed that the optimal CO2 adsorption capacity of 1.723 mmol/g was reached when operating with temperature of 323 K and PEI loading of 40%. The Freundlich model was applied to provide optimal correlations with the experimental data, and the correlation coefficients reached 0.997. The average isosteric heat of CO2 adsorption was calculated to be 67.492 kJ/mol. ...

Концентрирование некоторых антибиотиков фторхинолонового ряда методом магнитной твердофазной экстракции на наночастицах магнетита


 
 Исследовано влияние рН, природы буферного раствора, способа и времени установления
 сорбционного равновесия, концентрации антибиотика, температуры на степень извлечения, констан- ту распределения и коэффициент концентрирования энрофлоксацина, левофлоксацина и пефлоксаци- на на наночастицах магнетита, модифицированных полиэтиленимином. Показано, что количествен- ное извлечение антибиотиков в интервале концентраций 10-6-10-5 М со степенью извлечения 95-98% возможно при рН 3-4 из объема 50 см3 при использовании 18 мг наномагнетита. Получена изотерма сорбции, которая согласуется с моделью Ленгмюра. Методом просвечивающей микроскопии опреде- лены форма и размеры модифицированных наночастиц магнетита.

Smart delivery of vaccines.

A strategy to enhance antigen immunogenicity was developed by adsorption of polyethyleneimine on a mesoporous silica microrod vaccine for the presentation of tumour viruses and neoantigens, demonstrating their ability to drive anti-tumour immunity.

Magnetic Fe3O4-polyethyleneimine nanocomposites for efficient harvesting of Chlorella zofingiensis, Chlorella vulgaris, Chlorella sorokiniana, Chlorella ellipsoidea and Botryococcus braunii

A reduction in energy consumption at every stage of the down streaming process is needed to make 3rd generation of biofuels economically viable. In this study, magnetite (Fe3O4) nanoparticles were synthetized by coprecipitation of FeCl2 and FeCl3 in alkaline medium at two different temperatures. The particle sizes were 11.5 ± 4 and 9.5 ± 4 nm for the nanoparticles prepared at 80 °C and 25 °C, respectively. The adsorption of polyethyleneimine (PEI) onto Fe3O4 was studied by equilibrium batch measurements. A mono-layer absorption of PEI was found. The Fe3O4–PEI nanocomposites had a positive zeta potential, which decreased with increasing pH of the solution. The nanocomposites were used for magnetic harvesting of negatively charged Chlorella zofingiensis, Chlorella vulgaris, Chlorella sorokiniana, Chlorella ellipsoidea and Botryococcus braunii microalgae strains. Upon dosage of 200 mg/L of Fe3O4–PEI harvesting efficiencies of 68–97% were achieved at pH 4 within 1 min. The harvesting efficiency decreased with increasing pH of the suspension. The results demonstrate that Fe3O4 nanoparticles synthesized at the lower temperature (25 °C) could be used for an efficient magnetic harvesting of different microalgae strains. The lower synthesis temperature may thereby contribute to the cost reduction of microalgae harvesting.

Electrophoretically deposited halloysite nanotubes coating as the adsorbent for the removal of methylene blue from aqueous solution

Halloysite nanotubes (HNTs) coatings were prepared by electrophoretic deposition (EPD) from different alcoholic suspensions using polyethyleneimine (PEI) as the dispersant. The results of conductivity, zeta potential, FTIR and thermal analysis showed that PEI is protonated in alcoholic suspensions and then adsorbed on the surface of HNTs enhancing their zeta potential and so colloidal stability. Optimum concentration of PEI decreased with molecular size of alcohol due to the more adsorption of PEI on HNTs. Kinetics of EPD was the fastest from the suspensions with the highest zeta potential. HNTs coatings exhibited high resistance against cracking during their drying due to the self-reinforcement provided by long HNTs and the presence of PEI in their composition which acts as the binder. The coating (6cm2) deposited from ethanolic suspension with 0.5 g/l of PEI (optimum suspension) removed 36% of MB from its aqueous solution (concentration: 5 mg/l and volume: 30 ml) within 2 h.

CO2 adsorption performance of polyethyleneimine-modified ion-exchange resin

ABSTRACTA series of solid amine adsorbents were prepared by the template method with ion-exchange resin (D001) as the carrier and polyethyleneimine (PEI) as the modifier. The absorbents were characterized by energy disperse spectroscopy (EDS), scanning electron microscope (SEM), N2 adsorption–desorption, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) techniques. The effects of PEI loading, adsorption temperature and influent velocities on CO2 adsorption capacity in a fixed-bed reactor were investigated. The results show that the solid amine adsorbent prepared by the template method had a better PEI dispersion, stability and CO2 adsorption capacity. The maximum CO2 adsorption capacity was 3.98 mmol·g−1 when PEI loading was 30%, the adsorption temperature was 65°C and the influent velocity was 40 mL·min−1. The CO2 adsorption capacity decreased only by 9.50% after 10 cycles of adsorption–desorption tests. The study of kinetics indicates that both chemical adsorption and physical adsorption occurred in the CO2 adsorption process. The CO2 adsorption process included fast breakthrough adsorption and gradually approaching equilibrium stage. The particle internal diffusion process was the control step for CO2 adsorption.