Adsorption Structure Research Articles

Nanotube-Like Electronic States in [5,5]-C90 Fullertube Molecules.

Fullertubes, that is, fullerenes consisting of a carbon nanotube moiety capped by hemifullerene ends, are emerging carbon nanomaterials whose properties show both fullerene and carbon nanotube (CNT) traits. Albeit it may be expected that their electronic states show a certain resemblance to those of the extended nanotube, such a correlation has not yet been found or described. Here it shows a scanning tunneling microscopy (STM) and spectroscopy (STS) characterization of the adsorption, self-assembly, and electronic structure of 2D arrays of [5,5]-C90 fullertube molecules on two different noble metal surfaces, Ag(111) and Au(111). The results demonstrate that the shape of the molecular orbitals of the adsorbed fullertubes corresponds closely to those expected for isolated species on the grounds of density functional theory calculations. Moreover, a comparison between the electronic density profiles in the bands of the extended [5,5]-CNT and in the molecules reveals that some of the frontier orbitals of the fullertube molecules can be described as the result of the quantum confinement imposed by the hemifullerene caps to the delocalized band states in the extended CNT. The results thus provide a conceptual framework for the rational design of custom fullertube molecules and can potentially become a cornerstone in the understanding of these new carbon nanoforms.

PEGylation of a Peptide-Based Amphiphilic Delivery Agent and Influence on Protein Delivery to Cells.

The cell membrane is a restrictive biological barrier, especially for large, charged molecules, such as proteins. The use of cell-penetrating peptides (CPPs) can facilitate the delivery of proteins, protein complexes, and peptides across the membrane by a variety of mechanisms that are all limited by endosomal sequestration. To improve CPP-mediated delivery, we previously reported the rapid and effective cytosolic delivery of proteins in vitro and in vivo by their coadministration with the peptide S10, which combines a CPP and an endosomal leakage domain. Amphiphilic peptides with hydrophobic properties, such as S10, can interact with lipids to destabilize the cell membrane, thus promoting cargo internalization or escape from endosomal entrapment. However, acute membrane destabilization can result in a dose-limiting cytotoxicity. In this context, the partial or transient deactivation of S10 by modification with methoxy poly(ethylene glycol) (mPEG; i.e., PEGylation) may provide the means to alter membrane destabilization kinetics, thereby attenuating the impact of acute permeabilization on cell viability. This study investigates the influence of PEGylation parameters (molecular weight, architecture, and conjugation chemistry) on the delivery efficiency of a green fluorescent protein tagged with a nuclear localization signal (GFP-NLS) and cytotoxicity on cells in vitro. Results suggest that PEGylation mostly interferes with adsorption and secondary structure formation of S10 at the cell membrane, and this effect is exacerbated by the mPEG molecular weight. This effect can be compensated for by increasing the concentration of conjugates prepared with lower molecular weight mPEG (5 to ∼20 kDa) but not for conjugates prepared with higher molecular weight mPEG (40 kDa). For conjugates prepared with moderate-to-high molecular weight mPEG (10 to 20 kDa), partial compensation of inactivation could be achieved by the inclusion of a reducible disulfide bond, which provides a mechanism to liberate the S10 from the polymer. Grafting multiple copies of S10 to a high-molecular-weight multiarmed PEG (40 kDa) improved GFP-NLS delivery efficiency. However, these constructs were more cytotoxic than the native peptide. Considering that PEGylation could be harnessed for altering the pharmacokinetics and biodistribution profiles of peptide-based delivery agents in vivo, the trends observed herein provide new perspectives on how to manipulate the membrane permeabilization process, which is an important variable for achieving delivery.

Electron regulation and gas-sensitivity analysis of hBN-Graphene lateral heterojunctions——First principle study

In this paper, the first-principle calculations of the lateral heterojunction model synthesized by hBN-Graphene were carried out, and it was found that the bandgap of graphene varied with the change in the proportion of hBN, and the bandgap was best regulated with a bandgap of 1.177 eV when the proportion of hBN was 66.67 %. At this time, the adsorption structures of HCN, CO, NH3, and Cl2 were established and energy band calculations were performed on the hBN and Graphene portions of the hBN-Graphene lateral heterojunctions, respectively, and it was found that the adsorption of Cl2 resulted in a significant change in the band gap, which showed a very high electrical sensitivity. To further investigate the adsorption mechanism of Cl2 on the surface of hBN-Graphene lateral heterojunction, the energy band structure, PDOS, charge transfer, adsorption energy, and recovery time of each stabilized adsorption site of Cl2 on the surface of hBN-Graphene lateral heterojunction were calculated. The results show that the adsorption of Cl2 on the surface of hBN-Graphene lateral heterojunction is a stable chemisorption, and the band gap of C-Top1 increases to 1.274 eV, and the band gaps of C-Top3, N-Top1, and N-Top2 decrease to 0.684 eV, 0.376 eV, and 0.398 eV, respectively, and the changes of band gaps are significant and easy to be electrically detection. The recovery time of Cl2 on the surface of hBN-Graphene lateral heterojunction was 7.36 s–2.59 s in visible light and in the temperature interval of 273 K–283 K. The recovery time of Cl2 on the surface of hBN-Graphene lateral heterojunction was 7.36 s–2.59 s in visible light and in the temperature interval of 273 K–283 K. These findings have implications for the research and application of graphene-based Cl2 gas sensors.

CO adsorption on two-dimensional 2H-ZrO2 and its effect on the interfacial electronic properties: implications for sensing

Environmental pollution is commonly caused by direct and indirect greenhouse gasses and various traces of toxic gasses. CO is a tasteless, colourless and highly hazardous greenhouse gas that can bind with the hemoglobin much easier than oxygen. Materials with effective CO sensing capability are highly desirable. In this work, we have studied the repercussions of the molecular adsorption of toxic carbon monoxide (CO) on the structural, electronic, interfacial electronic and gas sensing properties of the two-dimensional (2D) 2H phase of zirconium dioxide (2H-ZrO2) using density functional theory (DFT) calculations. The most suitable adsorbent structure is screened out and interaction strengths between adsorbate molecule and adsorbent layer are provided in terms of binding energies. As a result of CO adsorption, the energy band gap (Eg) is altered and the resulting change in the conductivity of 2H-ZrO2 monolayer has implications for sensing. Energy band profiles relating to CO adsorbed 2H-ZrO2 reveal that fermi level shifts towards conduction bands exhibiting a development of n-type semiconducting character. Eg values relating to pristine and CO adsorbed 2H-ZrO2 sites such as TM, H, CB and B are 1.58, 1.98, 2.05, 2.06 and 2.03 eV, respectively. Further insights into the adsorption reveal that charge is accumulated near 2H-ZrO2 in the case of H and B adsorption sites, whereas for the case of TM and CB sites, depletion is noted. Essential gas sensing properties such as conductivity sensitivity (S), and recovery time (τ) are also reported. Notably, TM, CB, and B absorption sites depicted 17%, 2%, and 6% lower S values than H site. Furthermore, the H site achieved a shorter (32 ps) than the other adsorption sites. Response of pristine and CO adsorbed 2H-ZrO2 to that of incident photons is investigated with the help of real and imaginary parts [ and ] of complex dielectric function, electron energy loss function [] and joint density of states [] for a broader range of 0 to 10 eV. Major differences in dielectric function exist along in-plan and out-of-plan directions. After a detailed comparison, it is reported that more number of optical transitions exist between the linked states for the case of CO adsorbed 2H-ZrO2.

Improve the anchoring of 2D Ti2O electride in lithium-sulfur batteries through surface modification strategy: First principle study

Lithium-sulfur battery stands out in the next generation of rechargeable lithium batteries because of its high theoretical capacity (1675 mAh/g) and energy density (2600 Wh/kg). However, the shuttle effect seriously hinders the development and practical application of lithium-sulfur batteries. Here, we systematically studied the anchoring performance of two-dimensional (2D) Ti2O electride modified with N, O, F, P, S and Cl atoms in this paper. It was found that Ti2OF2 and Ti2OS2 showed excellent adsorption energy (1.21–2.62 eV), and their adsorption systems remained stable without obvious distortion, after the first principle calculation of the adsorption structure of Ti2OM2. In addition, Ti2OF2 and Ti2OS2 not only have excellent conductivity but maintain excellent conductivity after adsorbing Li2Sn, which indicates that they can effectively inhibit the shuttle effect and promote the performance of the battery.

Identifying Noble Metal Catalysts for the Hydrogenation and Dehydrogenation of Dibenzyltoluene: A Combined Theoretical-Experimental Study.

We present a comprehensive theoretical and experimental investigation of the hydrogenation and dehydrogenation of dibenzyltoluene (DBT) using Pd-, Pt-, Ru-, and Rh-supported metal catalysts to identify the optimal catalysts for hydrogen storage and release processes. Our results demonstrated significant variation in the catalytic activity of the metal catalysts. 5 wt % Rh/Al2O3 and 5 wt % Pt/Al2O3 showed the highest activity for hydrogenation and dehydrogenation with the highest selectivity and turnover frequency (TOF), respectively. Conversely, 5 wt % Pd/Al2O3 and 5 wt % Ru/Al2O3 exhibited lower catalytic activity toward full hydrogenation and dehydrogenation. Rh/Al2O3 showed the best catalytic hydrogenation activity with a TOF of 26.49 h-1 and a hydrogenation degree of 92.69% in 2 h, while Pt/Al2O3 exhibited the best catalytic dehydrogenation activity with a released H2 volume of 3755 mL, a dehydrogenation degree of 78.23%, and a TOF of 39.56 h-1 in 2 h. Additionally, we estimated the activation energies for hydrogenation and dehydrogenation to be 67.20 and 82.78 kJ/mol, respectively. Notably, the produced hydrogen gas was of high purity and suitable for use in fuel cells. Density functional theory (DFT) calculations were used to analyze the adsorption structure and reaction energy changes of all intermediate products of DBT on the surface of the chosen catalysts. Our research provides valuable insights into developing efficient catalysts for liquid organic hydrogen carriers.

Adsorption of NO2, SO2, H2S, and NH3 on Os-Doped WSe2 Monolayers: A First-Principles Study.

In this study, DFT calculations are used to analyze the adsorption of industrial waste gases (NO2, SO2, H2S, and NH3) on WSe2 monolayers. The adsorption energy, energy band, density of states, charge transfer, and recovery time of the adsorption structures between the target gas molecules and the Os-doped WSe2 are studied. Compared with pure WSe2 monolayer, Os surface bonding doping WSe2 (Os-modified WSe2) and Os doping with Se vacancy of WSe2 (Os-embedded WSe2) exhibit improved gas molecule adsorption ability. Among them, the adsorption energy of the Os-modified WSe2 monolayer on NO2, SO2, H2S, and NH3 is greater than that of the WSe2 monolayer. At the same time, it is proved that the Os-embedded WSe2 can be used as a gas sensor for H2S and NH3 gas molecules at a high temperature.

Theoretical investigation of outer-sphere adsorption of hydrated yttrium ion on the basal surfaces of kaolinite: A density functional study

Ion-adsorption deposits (IADs) are important types of REE deposits. Previous studies have found that, in IAD, REE3+ adsorb on the surface of clay minerals in the form of multi-coordinated hydrated complexes, [REE(H2O)8/9]3+, forming exchangeable outer-sphere adsorption complex. Actually, there are two types of basal surfaces in clay minerals, the (001) surface and the (00−1) surface, and it is not clear whether there are differences in the adsorptions on these two types. Additionally, the electron transfer mechanism in the adsorption structures cannot be revealed. To address these issues, we employ first-principles calculations based on density functional study to simulate the outer-sphere adsorption structures of representative Y3+ ion on the two types of basal surface of kaolinite. The study reveals that both the (001) surface and the (00–1) surface can serve as adsorption surfaces, but the (00–1) surface forms more stable adsorption structures with adsorbate-[Y(H2O)8]3+ due to the absence of hydroxyl group repulsion effects. The adsorption process involves electron transfer from the kaolinite basal surface to the adsorbate, forming hydrogen bonds. The primary orbital interaction in this process is between the O-2p orbitals of the adsorbate and the surface O-2p orbitals. This work contributes to a quantum-level understanding of the nature of ion adsorption in ion-adsorption deposit.

Research on the Effect of Coordinated Remediation of Heavy Metal Pollution in Roadbed Slope Soil by Combining Biochar with Reed

This study investigated the effect of modified activated carbon combined with plants on the coordinated restoration of heavy metal pollution in roadbed slope soil. This study used wheat husks as raw materials, potassium hydroxide and permanganate as modifiers, and aquatic plant reeds to remediate heavy metals in roadbed slope soil. The adsorption amount and removal rate of heavy metals Cu, Pb, and Cr were investigated under adsorbent dosage, adsorbent physical structure parameters, different pH environments, and ternary composite heavy metal body experimental conditions. According to the experimental results, after activation, the total pore volume and total specific surface area of biochar increased significantly, 21.4 and 111.7 times those before activation, respectively. The order of removal rates of heavy metal ions by different adsorbents was Pb > Cr > Cu. When the adsorbent was biochar–reed joint remediation, the maximum adsorption capacity of Cu, Pb, and Cr was 31.25, 136, and 52.3 mg/g. The adsorption capacities of the two adsorbents (biochar and biochar–reed) for Pb were the highest, and the adsorption sensitivity of the adsorbents for Pb was higher than that for Cr and Cu. Under single-component conditions, the adsorption capacity of biochar to heavy metals Cu, Pb, and Cr was ranked as Pb > Cu > Cr. In a ternary solution system, the adsorption capacity of biochar to heavy metals Cu, Pb, and Cr was ranked as Cu > Cr > Pb. Considering the adsorption capacity and removal rate of nutrient-rich substances, as well as the cost and effect of the use of the adsorbent, the recommended amount of the adsorbent was 4–6 g.

Efficient Cr(VI) sequestration from aqueous solution by chemically modified Garcinia kola hull particles: characterization, isotherm, kinetic, and thermodynamic studies.

There is a need for the removal of hexavalent chromium from contaminated water prior to its discharge into the environment, as part of industrial effluents, due to its toxic nature. In this present study, an adsorbent prepared via chemical modification of Garcinia kola hull particles (GK-HP) using NaOH was applied for Cr(VI) sequestration from aqueous solution. Both the raw (rGK-HP) and chemically modified Garcinia kola hull particles (cMGK-HP) were characterized using BET, SEM, XRD, FTIR, TGA, and EDS. The effects of pH, contact time, adsorbent dose, adsorbate initial concentration, and temperature on Cr(VI) sequestration were examined. The adsorbent, cMGK-HP, proved to be more effective for the adsorption process than rGK-HP with 96.25% removal efficiency at a pH of 2, a contact time of 60 min, an adsorbent dose of 5 g/L, Cr(VI) initial concentration of 20 mg/L and a temperature of 40°C. Isotherm and kinetic studies showed experimental data to be well-fitted with Langmuir isotherm and follow the pseudo-second-order kinetic model. The thermodynamic study revealed adsorption nature to be feasible, occur via physisorption, spontaneous, and exothermic. Changes in morphological structure, textural property, spectral peak, phase composition, and chemical composition of adsorbents before and after Cr(VI) sequestration from solution were proved by SEM, BET, FTIR, XRD, and EDS analyses, respectively. cMGK-HP possessed excellent reusability attribute and high thermal stability as shown by TGA. In conclusion, the adsorption capacity of cMGK-HP is better than many other adsorbents generated from agrowastes used in previous studies for Cr(VI) removal.

Effects of Charged Surfactants on Interfacial Water Structure and Macroscopic Properties of the Air-Water Interface.

Surfactants are used to control the macroscopic properties of air-water interfaces. However, the link between the molecular structure of surfactant adsorption and macroscopic properties is poorly understood. Using sum-frequency generation spectroscopy and molecular dynamics simulation, we show that two ionic surfactants (dodecyl trimethylammonium bromide and sodium dodecyl sulphate) with the same carbon chain lengths and head group charge magnitude (but different signs) can interact and reorient interfacial water molecules differently. DTAB forms a thicker but sparser interfacial layer than SDS. It is due to the deep penetration into the adsorption zone of Br- counterions compared to smaller Na+ ones, and also due to the flip-flop orientation of water molecules. SDS alters two distinctive interfacial water layers into a layer where H+ points to the air, forming strong hydrogen bonding with the sulphate headgroup. In contrast, only weaker dipole-dipole interactions with the DTAB headgroup are formed as they reorient water molecules with H+ point down to water. Hence, with more molecules adsorbed at the interface, SDS builds up a higher interfacial pressure than DTAB, producing lower surface tension and higher foam stability at a similar bulk concentration. Our findings offer improved knowledge for understanding various processes in the industry and nature.

Progress in Hemoperfusion Adsorbents of Common Toxins in Liver and Kidney Failure.

Liver and kidney failure can lead to extensive accumulation of toxic metabolites in the blood and tissues, such as bilirubin, blood ammonia, endotoxins, cytokines, creatinine, uric acid, and urea, which aggravate the progression of the disease. Hemoperfusion can effectively adsorb and remove toxins from the blood and treat liver and kidney failure. However, the adsorption efficiency and safety of traditional hemoperfusion adsorbents are not ideal. Thus, it is urgent to develop new toxin adsorbents with good blood compatibility, as well as high adsorption and strong selective capacities, to fulfill the growing clinical needs. In recent years, new hemoperfusion adsorption materials that can improve the adsorption performance of blood toxins while maintaining good blood compatibility have been developed, with promising potential for clinical applications. This review classifies and summarizes the recent research progress in hemoperfusion adsorbents for common blood toxins (bilirubin, blood ammonia, endotoxins, cytokines, creatinine, uric acid, and urea) produced by liver and kidney failure. The composition and structure of various toxin adsorbents, toxin adsorption performance, biocompatibility, blood safety, and the mechanisms of toxin adsorption are discussed. Based on a summary of recent studies, feasible strategies have been explored for designing and preparing hemoperfusion adsorbents to fulfill future development requirements. The trends and clinical application prospects of various toxin adsorbents are also discussed. This article is protected by copyright. All rights reserved.

Density functional theory study on the formation mechanism of CaClOH in municipal solid waste incineration fly ash.

Municipal solid waste incineration (MSWI) fly ash is defined as a kind of hazardous waste because of its high levels of multiple pollutants. The main component of MSWI fly ash is CaClOH, and the characteristics have not achieved consensus. And density functional theory (DFT) was used to calculate the formation process of CaClOH in this study, which mainly included HCl adsorption on CaO (0 0 1) surface and Ca(OH)2 (0 0 1) surface and the surface reaction process. The reaction mechanism was investigated. The results showed that the maximum adsorption energies of HCl on CaO and Ca(OH)2 surfaces reached - 195.17kJ/mol and - 83.48kJ/mol, respectively, representing strong chemisorption. The chemisorption process was shown as the adsorption of H atom on O site, and the adsorption capacity was reflected in the adsorption range of O site. The significant electron density overlap between O site and H atom meant that a new chemical bond formed, which made the adsorption structure stable. The adsorption energy of multi-HCl adsorption on the crystal surfaces was not proportional to the number of HCl molecule, indicating that the adsorption processes were influenced by each other. After surface reaction, the H-Cl bond was broken completely, and the structure of CaO and Ca(OH)2 changed to new structures. According to transition state (TS) search, the formation of CaClOH had a higher priority, easier than that of CaCl2, explaining the presence of CaClOH in fly ash. The study provides helpful information for the solidification treatment of fly ash.

Oil structuring from porous starch to powdered oil: Role of multi-scale structure in the oil adsorption and distribution

Oil structuring from porous starch is a potential alternative for the industrial production of powdered oil, but their relationship between starch multi-scale structure and oil adsorption characteristics was not clear. This study compared the role of multi-scale structure of porous starch (PS) prepared by normal and waxy maize starch in the oil adsorption. Waxy maize porous starch exhibited higher oil adsorption capacity (32.43 %–98.71 %) and more oil distributed on the surface of granules than normal maize porous starch, resulting from the more pores, larger specific surface area (1.01–1.53 m2/g), and pore size (8.45–9.32 nm). The enzymolysis time of native starch dominated oil distribution, leading to different granule adhesion and aggregation state. Pearson correlation analysis further showed oil adsorption capacity was negatively correlated with particle size, but positively correlated with enzymolysis rate and specific surface area of PS. The formation of powdered oil was mainly through the physical adsorption, including surface adsorption and pore adsorption. These findings could provide a promising route for the preparation of powdered oil with controlled multi-scale structure of PS.

Bioinspired supramolecular arrayed heterojunction-based room-temperature sensor for high-performance gas detection

Nitrogen dioxide (NO2) has been severely polluting the atmosphere and deteriorating human beings’ sustainable lives. Therefore, development of gas sensors for high-selectivity and high-sensitivity detection of NO2 has been attracting increasing attention. The state-of-the-art inorganic NO2 gas sensors require harsh fabrication conditions or toxic materials, making the devices intrinsically eco-unfriendly. Furthermore, in most cases the sensors work at high temperatures. These disadvantages severely impede their practical applications. Herein, we report a room-temperature and highly-integrated NO2 sensor composed of p-type self-assembled peptide fibrillar nanoforests (SPNFs) scaffolded with n-type SnO2 nanoparticles (NPs) heterojunctions. The p-n conformations provide efficient access to target gases and allow reliable electron transformations, while the SPNFs afford a large specific surface area and multiporous structures for gas adsorption and SnO2 NPs dispersion, resulting in an ultrahigh selectivity for NO2 detection. Especially, the sensing performance can be optimized by modulating the thickness and density of the SPNFs, showing a high response, short response and recovery times, along with a low detection limitation. Our strategy demonstrates the development of a bioinspired platform by utilizing peptide self-assemblies to fabricate integrated sensors for polluting gas detections.

Adsorption and sensing performances of air decomposition components (CO, NOx) on Cr modified graphene surface

The adsorption and sensing abilities of air decomposition components such as CO, NO, and NO2 on a Cr-graphene monolayer were investigated using the first principles of density functional theory. Firstly, three possible doping points of Cr atoms on the surface of graphene were studied, and the most stable Cr-graphene monolayer was obtained through modeling and computational analysis. Then, various adsorption structures were constructed and optimized based on the model. The most stable adsorption structure of Cr-graphene monolayer for the three characteristic gases was determined by comparing their adsorption energy and other relevant parameters.Furthermore, state density, differential charge, and molecular orbital theory analyze the gas sensing mechanism and desorption time. The results show that the surface of the pristine graphene has a weak adsorption effect on these gases, and the Cr-graphene monolayer has good adsorption performance for the three gases. Although the calculation results show that Cr-graphene monolayer has strong adsorption and gas sensitivity performance for the three components, the recovery performance of the Cr-graphene monolayer needs to be improved because of the immense adsorption energy of Cr-graphene monolayer for the three components. The calculation can provide a theoretical guidance for gas sensors based on graphene and its modified materials.

The adsorption behaviors of Cl2 on TiC (100) surface: A density functional theory study

It is important to study the adsorption behavior of Cl2 molecules on the TiC surface and the formation and transfer of reaction products to understand and to regulate the low-temperature chlorination reaction process of carbonized titanium-bearing slag. Based on the first-principles ab initio calculation method of density functional theory (DFT), the adsorption models of Cl2 molecules on the TiC (100) intact surface and the surface with carbon vacancy are established, and the adsorption structures, electronic properties, differential charge density and partial density of states (PDOS) are calculated and analyzed. The formation process and the optimal formation path of the adsorption reaction product are explored. The investigated results indicate that the Cl atoms in the system bonded to the surface Ti atoms are more stable than the structure formed by bonding to the surface C atoms. The electron flow direction is Ti → C and Ti → Cl. In the reaction of TiC with Cl2 molecules, the TiCl3 intermediate is easier to form than the TiCl2 intermediate. The energy barrier to be overcome to form the TiCl3 intermediate is lower and the energy to be supplied is easily met by external conditions. TiCl3 is then further chlorinated to form TiCl4.

Adsorptive separation of CH4, H2, CO2, and N2 using fullerene pillared graphene nanocomposites: Insights from molecular simulations.

The adsorptive separation performances of fullerene pillared graphene nanocomposites (FPGNs) with tunable micro and meso porous morphology are investigated for the binary mixtures of CH4, H2, CO2 and N2 by using grand canonical Monte Carlo (GCMC) simulations. Different fullerene types are considered in designs as pillar to investigate the effects of porosity on the gas separation performances of FPGNs, and the GCMC simulations are performed for an equimolar binary mixture of CO2/H2, CO2/CH4, CO2/N2 and CH4/H2 inspired by industrial gas mixtures. It is found that CO2/N2, CO2/H2 and CH4/H2 selectivity of FPGNs are about 72, 410 and 145 at 298K and 1bar, which are higher than those for several adsorbent materials reported. Five different FPGN models which contain covalently bonded periodical fullerene and graphene units were constructed using C60, C180, C320, C540 and C720 fullerenes, followed by geometry optimization using Open Babel. All GCMC simulations of adsorption were performed in the RASPA. The adsorption isotherms of FPGNs for pure gases are comparatively examined, and their performances are discussed based on the pore structure and isosteric heat of adsorption. Then, the separation factors of FPGNs for equimolar binary mixtures of these gases are elucidated from the difference in the heat of adsorption and the adsorption selectivity.

Role of imperfect coordination of amorphous metal oxide in its chemical reaction with epoxy resin in metal − polymer hybrid material

The chemical bonding between laser − induced metal oxide and polymer highly determines the interfacial bonding performance of metal − polymer hybrid materials. To achieve reliable interfacial chemical bonding, it is crucial to gain a molecular/atomic level understanding of the chemical reaction mechanism between the metal oxide and epoxy resin (main components of epoxy polymer). Previous research has demonstrated that laser ablation induces the formation of amorphous aluminium oxide on aluminium alloy surfaces. Our solid − state nuclear magnetic resonance (ssNMR) investigation reveals that this amorphous aluminium oxide is consisted mainly of 4 − fold and 5 − fold coordinated Al sites. Through an innovative combination of ssNMR and density functional theory calculations, this aluminium oxide was confirmed to form Al − O − C bonds with epoxy resin, preferentially at imperfectly coordinated Al sites due to active donor − acceptor interactions. It is clarified that imperfect coordination of amorphous aluminium oxide plays a more critical role than its amorphous nature in forming stable adsorption structure with epoxy resin. Furthermore, compared to on crystalline surface, 5 − fold coordinated Al site on amorphous surface exhibits higher reactivity, and the origin of activity is revealed through distortion/interaction analysis. This study provides a research guidance for further regulation and optimization of interfacial reactivity and bonding characteristics of metal − polymer hybrid materials.

Facile and controllable preparation of nanosheet hierarchical Y for enhanced adsorptive denitrogenation from fuels

Adsorptive removal of nitrogen containing compounds (NCCs) from high temperature coal tar over Y zeolites has received more attention for its mild operating conditions. In order to eliminate the diffusion limitation caused by zeolites micropores, a series of nanosheet hierarchical Y zeolites have been synthesized through a three–stage temperature method without the addition of template in this work. The results indicate that the particle size, pore structure and acid properties of synthesized samples can be easily tuned by controlling the H2O/SiO2 ratio of precursor gel, which was confirmed by a series of analysis. The adsorbent with the H2O/SiO2 ratio at 20.1 consists of best relative crystallinity of primary zeolite, the highest BET surface of 850 m2·g−1, the highest total acidity of 0.43 mmol·g−1 and the largest amount Lewis acid sites (LAS) of 928.2 μmol·g−1, which made it a superior candidate for denitrogenation adsorbents. In addition, the relationship between the structure of adsorbents and their denitrogenation performance was evaluated by batch adsorption experiments in model fuels. The results demonstrate that the ZY20.1 exhibited the highest adsorption capacity of 17.09 mg N·g−1 adsorbent for quinoline (QUI) and 21.51 mg N·g−1 adsorbent for indole (IND), respectively, which is roughly twice that of the conventional NaY. ZY20.1 also has an excellent adsorption selectivity for NCCs and can effectively resist the effect of competitive components. Furthermore, the adsorption performance in real fraction and its good regeneration performance of ZY20.1 confirm its potential commercial application. In this study, a kind of structurally controllable nanosheet Y zeolite with enhanced adsorptive denitrogenation was prepared by a green and environmental method, which will provide useful guidance for the development of efficient denitrogenation material.