AlOH Research Articles

Spider Webs‐Inspired Aluminum Coordination Hydrogel Piezoionic Sensors for Tactile Nerve Systems

AbstractPiezoionics, a new frontier that employs mobile ions as energy and charge carriers, plays an important role in new energy and intelligent electronics. However, a significant challenge consists in balancing the structural design of metal ions coordination hydrogel (HG‐MI) piezoionics for current conduction, voltage generation, and especially mechanical adaptability. Herein, inspired by the spider webs' unique structure, a strategy by realizing the full potential of metal‐ligand ions ([(OH)Cl2]3−) to facilitate the keggin‐type structure AlOHAlOH generation together with activate functional carboxyls is introduced. Impressively, the whole property of the product HG‐AlPAC, especially the mechanical performance is improved. For example, the toughness of HG‐AlPAC is 2.75 MJ m−3, more than twofold that of traditional HG‐AlAS/AC/AN samples. Due to the stable fixation of ─Al─OH─ thus promoting Cl− separation upon external force, HG‐AlPAC achieves a piezoionic coefficient of 0.89 mV KPa−1 and energy conversion efficiency of 1.29%, promising for mechanical‐electrical conversion and sensing. Combined with the good mechanical performance with the excellent piezoionic properties, underscores its potential as a tactile nerve system of analgesia patients to prevent them from being injured. This work intends to provide a stride toward mechanically robust self‐powered piezoionic sensors and offer insights into ionotropic materials for energy harvesting, human‐machine interaction, and biointerface.

Resistance to acid, alkali, chloride, and carbonation in ternary blended high-volume mineral admixed concrete

The World Bank study predicts that 4 °C warming will bring high temperatures, sea-level rise, and saltwater intrusion to coastal areas, damaging coastal concrete structures. Increased CO2 from industrialization exacerbates this, necessitating durable, low-carbon concrete. Combined use of fly ash (FA) and ground granulated blast furnace slag (GGBFS) as high-volume OPC replacements boosts performance while reducing concrete’s carbon footprint. In this perspective current study examines the durability of concrete against aggressive agents (H2SO4, MgSO4, NaCl, and CO2) causing premature deterioration of concrete structures. Initially, three cost-effective sustainable concrete mix designs were developed, incorporating 50% replacement of OPC with locally available supplementary cementitious materials, specifically FA and GGBFS. These mixes were then evaluated for their mechanical and durability performances. The impact of aggressive ions (SO4 2−, Cl−, and CO3 2−) was studied by examining the changes in mechanical performance and phase assemblages. Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) techniques were used to estimate the phase compositions. Ternary blended concrete having 50% OPC+ 30% GGBFS + 20% FA exhibited optimal synergistic performance, enhancing pozzolanic and hydraulic reactions for better resistance to harmful ions. The sorptivity test confirmed that as the GGBFS content increased, the sorption rate decreased, indicating the higher reactive nature of GGBFS to that of FA. Deleterious compounds formed due to the action of SO4 2-, Cl-, and CO3 2- were identified to be ettringite (Ca6Al2(SO4)3(OH)12.32H2O, AFt) and gypsum (CaSO4.2H2O, Gy), Friedel’s salt (Ca4Al2(OH)12Cl2.4H2O, Fs) and polymorphs of calcium carbonate (CaCO3), respectively through TG mass loss curve. These results were corroborated by FTIR analysis, which showed predominant characteristic bands at 662 cm−1 for SO4 2−, 459 cm−1 for Mg–O stretching, 790 cm−1 for Al–OH bending, and 1431-1443 cm−1 for C–O, confirming the presence of the deleterious compounds.

Utilizing supercritical fluid for efficient preparation of kaolinite nanosheets to enhance Ga(Ⅲ) adsorption

This study explores the efficient preparation of few-layered or monolayered kaolinite (K) nanosheets using supercritical gasification exfoliation technology, aiming to enhance their adsorption capacity for Ga(III). Crystal structure and morphology analysis indicated that the exfoliated K nanosheets maintained an excellent hexagonal lamellar crystal shape, with significantly reduced thickness (∼10 nm) while maintaining an unchanged lateral dimension (400 ∼ 600 nm). The exfoliation mechanism primarily relies on the considerable impact force generated by the rapid expansion of supercritical carbon dioxide (CO2) volume during fast pressure release, which facilitates exfoliation between K layers where the interlayer hydrogen bonds have been disrupted by potassium acetate. Batch adsorption experiments demonstrated a significant improvement in the removal rate of exfoliated K for Ga(III), increasing from 50.66 % to 80.47 % under the conditions of a Ga(III) concentration of 15 mg/L and an adsorbent dosage of 0.4 g/L, attributed to the exposure of numerous active sites. Kinetic and isotherm fitting results indicated a monomolecular adsorption process primarily controlled by chemical adsorption, with a maximum theoretical adsorption capacity of 32.90 mg/g for Ga(III). In multivariate mixed adsorption experiments, exfoliated K exhibited good adsorption selectivity for Ga(III), primarily through chemical adsorption of aluminum hydroxide (Al–OH) functional groups and electrostatic adsorption of silicon oxide (Si–O). Density functional theory (DFT) calculations further demonstrated that the bidentate adsorption coordination of K with Ga(III) exhibits higher stability compared to monodentate adsorption coordination, indicating that the adsorption process is mainly dominated by bidentate adsorption. Consequently, the supercritical gasification exfoliation technology, as a recyclable green process, offers efficient exfoliation of K, holding significance implications for the high-value and high-efficiency utilization of K resources, as well as for establishing a green, low-carbon, and recycling development economic system.

Adsorption behavior of NH4+ and Mg2+ at kaolinite surfaces: Effect of the ion concentration, NH4+/Mg2+ mixing ratio, and layer charge

AbstractThe adsorption behavior of NH4+ and Mg2+ at kaolinite surfaces was investigated by using molecular dynamics (MD) simulations, considering the factors such as ion concentration, NH4+/Mg2+ mixing ratio, and layer charge of kaolinite. The results showed that the increase in ion concentration did not affect the adsorption modes of NH4+ and Mg2+ ions but promote the increase in the adsorption capacity. The total adsorption capacities of Mg2+ and NH4+ were 3.25 × 10−6 and 2.85 × 10−6 μmol·mm−2 at the ion concentration of 1.5 mol·L−1, respectively. When NH4+ and Mg2+ were co‐adsorbed, they could inhibit the adsorption of each other at the surface of kaolinite, except that the inner‐sphere (IS) adsorption of NH4+ at aluminum hydroxyl (Al–OH) surface could be enhanced by the presence of Mg2+. Both NH4+ and Mg2+ tended to adsorb at the siloxane (Si–O) surface of kaolinite rather than Al–OH surface. When layer charge occurred in kaolinite, a small number of Mg2+ began to adsorb in the IS complexes at 1.7 and 2.3 Å above the Al and O atoms of the lattice‐substituted tetrahedra of the Si–O surface, and at 1.7 Å above the hexahedra of the Al–OH surface. However, most of NH4+ were adsorbed in IS complexes at 1.7 Å above the center of the oxygen six‐membered ring of the Si–O surface and above the hexahedron of the Al–OH surface. The adsorption capacity of Mg2+ changed little with the increase of layer charge density, while the IS and total adsorption capacity of NH4+ increased significantly.

The use of ASTER and landsat remote sensing data for exploring hydrothermal mineral in Arabian-Nubian Shield

Multispectral remote sensing data provided valuable information for hydrothermal minerals exploration. In this article, Landsat-8 Operational Land Imager (OLI) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data were processed and analyzed using band ratio and principal component techniques to demarcate areas of hydrothermal mineral resources by highlighting the most influenced zone of hydrothermal alteration (high-grade) in Egypt. The area is a part of the Arabian-Nubian Shield, covering 1068 km2, and comprises wide varieties of Pre- and Pan-African rock assemblages. Preparing and integrating thematic layers consisting of the grade of hydrothermal intensity in a GIS technique supported generating a hydrothermal mineral predictive map (HMPM) using a multi-criteria decision-making technique. The plausible zone of very high mineral resources covers about 6.57 %. Analysis of ASTER data revealed that this zone is reliable with phyllic and argillic minerals and iron-oxides. The results of OLI data helped in demarcating potential areas of hydrothermal alteration areas (Al–OH) mixed with iron oxides. Field observations and investigations enabled the validation of the HMPM. The spatial distribution of hydrothermal zones throughout the study was reliable to that observed in the mine areas. Field and ore microscopic examination verified the existence of Au-sulfide minerals connected with hydrothermal alteration zones (HAZs) in different areas e.g., Abu-Marawat, Gidami, Semna, Abu-Gaharish, and Hamama mines. Overall, integrating multi-spectral data through overlay analysis techniques can provide valuable information about hydrothermal mineral resources in an accurate and cost-effective approach.

Short-Wavelength Infrared Characteristics and Indications of Exploration of the Jiawula Silver–Lead–Zinc Deposit in Inner Mongolia

For the Jiawula lead–zinc deposit, as easily accessible resources become depleted, mines are becoming deeper to replenish ore reserves. Identifying large, continuous, and high-grade ore bodies in deep areas has become a daunting problem. Moreover, separating lead–zinc-bearing complex ore bodies from waste material and extracting them from associated minerals are also difficult. Thus, pioneering exploratory strategies and technological methodologies are required to make breakthroughs in mineral discovery. Based on extensive-scale structural lithofacies mapping, this paper uses short-wave infrared (SWIR) spectroscopy technology to investigate hydrothermal alteration minerals in the mining area. It has identified a total of 16 hydroxyl-bearing alteration minerals, including chlorite, muscovite, illite, calcite, ankerite, kaolinite, and smectite. These minerals establish zoning characteristics around the ore bodies and on their flanks. They comprise a segmented assemblage that follows the pattern of comb-textured quartz–illite–chlorite–carbonate → muscovite–illite–chlorite–ankerite → illite–smectite–chlorite → chlorite–kaolinite–calcite. Deep-zone illitization with a lower Al–OH absorbance peak wavelength (<2206 nm) and higher crystallinity indices (>1.1) and chloritization with higher Fe–OH absorbance peak wavelengths (>2254) and higher crystallinity indices (>3.0) are indicators of potential hydrothermal centers in the deeper regions. By finding hydrothermal centers and connecting their spatial distribution with existing ore bodies, a pertinent relationship between diabase + andesite, Fe-chlorite + illite, and high-grade mineralization has been established. They correspond well with the lithology-alteration mineralization. This research provides a basis for predicting the positioning of concealed ore bodies deep inside a mine or at the periphery.

Investigation of the composition and morphology of raw materials from the Aral Sea region

Abstract Clay and clay-based minerals have attracted research attention because of their unique properties and a vast range of applications in industry. In order to assess the potential applications, four different processed local kaolin-based raw minerals were collected from the Aral Sea region of Uzbekistan, and the total mineralogical properties have been explored. The results reveal that the structural, vibrational and electronic properties of metakaolinites only slightly differ from those of kaoline. The presence of corundum, quartz and kaolinite structural phase in minerals was determined by XRD analysis. FTIR and Raman studies expose the primary peaks which are associated with the functional groups of Al–OH, Al–O and Si–O in higher-frequency stretching and lower-frequency bending modes. The elemental and chemical compositional (XRF and XPS) analysis demonstrates the presence of major elements (Al, Si, Na, Fe, Ti) in the raw mineral and other metal contaminations (Mg, Ca, S, Cr, Zr). The SEM analysis demonstrates the morphological nature of kaolin-based raw minerals that can be exploited for industrial purposes.

Atomic transport properties of water in barium–strontium aluminosilicates: Coupling of reactions and diffusion

AbstractBarium–strontium aluminosilicate (BSAS), with excellent resistance to water vapor corrosion and low water permeability, is considered an ideal environmental barrier coating material. Water vapor plays an important role on the failure of BSAS when it is exposed to service environments. Herein, the atomic transport properties of water in BSAS are investigated using ab initio calculations. The metastable structure of water in BSAS mainly consists of hydroxyl group and H+, where the hydroxyl group mainly exists in the form of Al–OH structure. In BSAS crystals, water first reacts with the aluminosilicate network to form metastable hydroxyl group and H+, and then hydroxyl group and H+ diffuse through the aluminosilicate network. Alkaline earth elements limit the diffusion behavior of water and improve the resistance to water vapor corrosion by maintaining the desired local charge balance of the Al–O4 tetrahedron structure. Furthermore, the ab initio molecular dynamics calculations at service temperature and pressure of BSAS are carried out to verify the above conclusions.

Characterization of Acid Activation of Bentonite Clay of Hadar, Afar, Ethiopia

The applications of various clay minerals are related to their structural, physical, and chemical characteristics. These properties of the clay minerals dictate their utilization in the industries and beneficiation required before usage. The study aimed at establishing the potentiality of acid‐activated clay mineral from Hadar, Afar, Ethiopia. XRD, SEM, energy‐dispersive X‐ray fluorescence (EDXRF), and FT‐IR spectroscopies were employed to characterize the chemical compositions and interaction in the bentonite samples. The XRD results revealed that the native and activated bentonite clay contains similar minerals, such as montmorillonite (MMT) ([Ca, Na]0.33 [Al, Mg]2[Si4O10][OH]2.nH2O), quartz (SiO2), albite (NaAl2SiO6), zeolite (CaAl2O3.SiO2.nH2O), and aluminum silicate. Thus, attributes of the bentonite clay was composed of SiO2 and Al2O3 indicating that it is an aluminosilicate mineral, and the morphology of bentonite was supported by SEM. The chemical analysis by EDXRF revealed that the native bentonite (NB) consisting of 58.18 wt% (SiO2), 14.28 wt% (Al2O3), and Na2O > CaO are the major constituents of the clay with other oxides present in low amount. There was an increase in the SiO2 content in activated bentonites, and the Al2O3, Fe2O3, and MgO contents have decreased by 48.56%, 66.36%, and 84.42%, respectively. The FT‐IR spectra bands at 1627 cm−1 and 1027 cm−1 were attributed to Al–Mg–OH, Al–Al–OH, and Al–OH–O–Si stretching vibration, and the reduction of the content of the octahedral cations is accompanied by a decrease of both OH bending vibrations at 1627 and 3401 cm−1. The FT‐IR result is in clear agreement with the SEM, XRD, and EDXRF studies which indicate sequential degradation of the clay sheet upon acid treatment. Hence, rendering the activated bentonite clay of Hadar has accounted for their demand for different industrial applications such as its use as detoxifier, sealant, binder, fillers for paper, pharmaceutical products, absorbent, adsorbent, catalyst, and nanoclays.

Interface, thermal, and Fourier transform—infrared spectroscopy investigation on polylactic acid/polyhydroxyalkanoate composites with silane‐treated aluminum particles and intercalated montmorillonite inclusions for semiconductor devices

AbstractIn this investigation, the dielectric properties of silane‐influenced aluminum conductive particles in polylactic acid, polyhydroxyalkanoates, and intercalated montmorillonite (MMT) composite were assessed for enhancing the dielectric constant, dielectric loss, and AC conductivities. Eight different sets of samples were fabricated with untreated and silane‐treated batches of biopolymer composites where the highest recorded dielectric constant was 3.98 at relaxation frequency of 10 kHz. One of the notable observations in the dielectric loss was with PLA/PHA/iMMT/Al (10 wt%) (silane‐treated) composites exhibited the lowest losses past relaxation frequencies. Furthermore, FT‐IR spectra were conducted on the samples to identify stretching and bonds created by silane and aluminum particles. The IR spectra confirm the formation of the SiOAl bond when treated with 3‐glycidyloxypropyl‐trimethoxysilane (GPTMS) solution and confirm the bond of AlOH hydroxyl bonds in the untreated composite samples. Other IR spectra information that was gathered would include carbonyl group stretching at 1750 cm−1 and absorption bands of hydroxy acids, between 3511 and 3640 cm−1, respectively. Scanning electron microscopy was performed on the sample to observe the formation of matrix cracks and exfoliation. A rough surface can be seen on PLA/PHA blends and the crystallization of these polymer blends regions can be vividly seen from the micrographs. Lastly, thermogravimetry analysis on the composite samples shows a predominant mass loss at 300°C before complete degradation and the notable composite with the lowest mass loss would be PLA/PHA/iMMT/Al (10 wt%) (ST) composite samples and with the inclusion of a constant 5 wt% organoclay MMT fillers imposed a high‐onset degradation temperature, which was remarkable for composites that were fabricated through standard hot‐press compression molding and cooling procedures.

Bioactivity properties of hydroxyapatite/clay nanocomposites

The need for bioactive and non-toxic biomaterials is on a high demand in tissue engineering applications nowadays. Hydroxyapatite (HAp) is the chief constituent of teeth and bones in mammas. One of the major challenges with the use of HAp in engineering application is its brittleness and to overcome this, it’s important to react it with a material that can enhanced it’s fragility. To this end, HAp and HAp/clay nanocomposites were developed via wet chemical process to mimic natural HAp and to equally confer special properties such as mechanical properties, high surface area, crystallinity, high porosity, and biocompatibility on the biomaterial. The functional groups properties of the as-prepared nanocomposites analyzed by FT-IR showed that the HAp and clay posed reactive centers such as Al–Al–OH, Si–Si–OH, Si–O, PO43−, –OH, and Si–O–Al. The XRD results confirmed the formation of HAp/clay nanocomposite, while SEM and TEM images showed the morphologies of the prepared nanocomposites to be round shape particles. Besides, EDX result revealed the Ca/P ratio of HAp and HAp-C to be lower than that of stoichiometric ratio (1.67) which implies the presence of K, Na, Ca, Mg, Si and Al in the HAp/clay nanocomposite. The mechanical properties of the apatite were greatly enhanced by the addition of clay. The physiological behaviour of the fabricated apatite composites in saline solution showed steady increase in the values of the saline pH of the various biomolecules until day 5 and became fairly constant at day 7 with pH range of 7.30–7.38. Though the saline solution was acidic at the beginning due to dissolved carbon dioxide, the pH of the saline solution containing the nanocomposites gradually became neutral and fairly alkaline over time as a result of the presence of Lewis basis structures in the composites which helps in neutralizing the acidic solution. Furthermore, proliferation of apatites particles onto the surface of the nanocomposites was observed after treatment with simulated body fluids (SBF) media for 7 days. Thus, HAp/clay nanocomposites can be useful biomaterials in bone tissue engineering.

Application of the Landsat-8 Data Set and the Digital Elevation Model SRTM to Prediction Gold-Polymetallic Mineralization to the Central Part of the Malouralskaya Zone, the Polar Urals

For the first time for the central part of the Malouralskaya zone of the Polar Urals, a new approach to processing data from remote sensing of the Earth was applied. The data were obtained using the Landsat-8 spacecraft. It consists in integration hydrothermal alteration propagation patterns and lineament density maps. They are based on the results of statistical processing of remote sensing data and digital elevation model SRTM (The Shuttle Radar Tpography Mission). The work was carried out in order to identify morphological features and patterns, features of the deep structure and identify promising areas of localization of gold-polymetallic mineralization in the study area. As a result of the study, it was found that areas promising for the gold-polymetallic type of mineralization in the central part of the Malouralskaya zone are localized within trans-regional fault zones, crossing favorable horizons and structures, and controlling ore mineralization, morphostructures, complicated by radial discontinuous faults of the 1st order NE and NW direction with a length of up to 30 km, as well as zones of increased indices II and III, less often hydroxide-(Al–OH, Mg–OH) and carbonate-containing minerals.

Plasma power effect on crystallinity and density of AlN films deposited by plasma enhanced atomic layer deposition

Aluminum nitride (AlN) film is a promising material which is used in various fields. In this study, AlN films with different plasma powers were grown by remote plasma atomic layer deposition. Saturation experiments have been applied in the plasma power between 1000 and 3000 W. The influence of plasma power on preferential orientation, chemical, optical, and electrical properties of AlN films are investigated. AlN films displayed multiphase hexagonal wurtzite crystal structure with (002) preferential orientation for higher plasma power, while the predominant orientation shifted toward (100) at lower plasma power. The optical emission spectroscopy analyses show that NH and NH2 radicals conduce to the deposition of AlN films and H radicals selectively dissociate Al–OH bonds which were on AlN film surface and etch deposition films. Atomic force microscopy measurements show that the 1500 W prepared AlN film with smallest surface roughness may be related to the relatively smaller concomitant crystal grains of (100) and (002). X-ray photoelectron spectroscopy investigation presents that oxygen content decreases as the plasma power increases. The obtained maximum value of dielectric constant and breakdown electrical field of AlN film deposited at 3000 W is 8.23 and 5.42 MV/cm, respectively.

An overlooked crystallization effect during the O3 participated coagulation improves the performance of dual-membrane process

Till now, the transformation of amorphous flocs formed during the hydrolysis stage of coagulation has not been fully addressed. In this work, by using a conventional coagulant (alum), the transformation process was explored by observing the interactions between O3 and the amorphous alum flocs formed during flocculation at neutral pH. It was found that O3 promoted the transition of the in-situ formed alum flocs from tetrahedral Al (Al(O)4) to octahedral Al (Al(O)6) structures, through an accelerated dehydroxylation process, and therefore facilitated the crystallization process to form boehmite. During this process, the surface functional groups of amorphous Al flocs (Al–H2O and Al–OH) were observed to take part in the O3 catalytic oxidation with the generation of hydroxyl radicals (OH). This synergistic effect significantly favored the performance of the subsequent dual-membrane (UF-NF) process in terms of both fouling alleviation (1.78 and 1.60 times higher flux of UF and NF, respectively) and final effluent quality improvement, including the reduction in disinfection byproduct (DBP) formation potential (48.1% and 22.4% lower generation of total trihalomethanes and total haloacetic acid, respectively) and the corresponding calculated toxicity. The results obtained here provide a greater understanding of the transformation of amorphous Al flocs formed during flocculation with O3, and valuable information regarding its practical application in membrane filtration process with greater treatment performance.

Lithological discrimination and mineralogical mapping using Landsat-8 OLI and ASTER remote sensing data: Igoudrane region, jbel saghro, Anti Atlas, Morocco

This study aims to delineate the lithological formations, in addition to a mineralogical mapping comparing between the ASTER and Landsat-8 OLI sensors in the Igoudrane region. The research was accomplished using BR along with spectral profiles of minerals, PCA, MNF, ICA, XRD, and reflectance spectrometry. The BR measured with ASTER revealed the presence of amphibole, illite, smectite, muscovite, phengite, basic degree index SiO2, calcite, chlorite, epidote, dolomite, hydroxides, and ferrous silicates. Furthermore, Landsat-8 OLI BR highlighted areas with oxides, hydroxides, and laterite. The spectral profiles of minerals showed their absorption in the VNIR and SWIR regions. The muscovite and illite (phyllic alteration) are distinguished by Al–OH absorption at 2.20 μm. The argillitic alteration is additionally defined by muscovite, illite, and Kaolinite, where Kaolinite has a high absorption at 0.9 μm. Chlorite and carbonates characterized the propylitic alteration zone, with an absorption ranging between 2.3 μm and 2.35 μm due to CO3 and Mg–OH compositions. The oxidation (hematite and jarosite) was distinguished by absorption near 0.95 μm and 2.3 μm, respectively, whereas the goethite spectral profile exhibits absorption near 1.4 μm and 2.2 μm. The absorption of smectite is 1.4 μm, near 2.2 μm. The amphibole had absorption near 1.4 μm and 2.3 μm, whereas the pyroxene had absorption near 1.4 μm and 2.3 μm. The first three components of PCA, MNF, and ICA showed the highest eigenvalues and gave an appreciable discrimination of the lithologies, especially with ASTER. Moreover, the XRD quantified the mineralogy of the rocks, which were compared to the BR of ASTER. The reflectance spectrometry also provided alteration minerals, such as muscovite, phengite, illite, Fe–Mg chlorite, Fe-chlorite, iron oxides, hydroxides, hornblende, and calcite. Overall, the methodology adopted has shown great performance and strong potential for mapping alteration areas and lithological discrimination in similar arid regions.

Mechanism insight into ethylene oligomerization on zeolite K-LTA surface: A DFT and kMC study

The regeneration gas used in the K-LTA zeolite dryer of the MTO plant is planning to be changed from high purity nitrogen to the top gas of the demethanizer tower with high ethylene content, which is helpful to energy saving and emission reduction. However, there is a risk of ethylene oligomerization and carbon deposition when the regeneration gas passes through the K-LTA zeolite. The reaction mechanism of ethylene oligomerization on the K-LTA zeolite surface must be clarified. DFT calculations showed that ethylene could be physically adsorbed on Si–OH, Al–OH, the incomplete α- and β-cage on [100]-D4R-e surface. Butoxide forms through ethylene dimerization by stepwise and concerted mechanisms first. Then the reaction of ethylene and butoxide to n-hexyloxide leads to the continued growth of the carbon chain. The oligomerization reaction barriers of rate-determining steps are between 1.65∼1.75 eV, which is more difficult to occur than other zeolites. The ethylene oligomerization reaction can be divided into stepwise polymerization path, concerted polymerization path and concerted butene path. kMC simulation found that the dominant reaction paths are different under different temperatures. When the regeneration temperature reaches 473 K, trace n-butene is generated. At 513 K, ethylene oligommerization occurs and carbon deposition is formed. The results put forward higher requirements for strictly controlling the temperature of the dryer to ensure the excellent performance of K-LTA zeolite.

Understanding the changes in engineering behaviors and microstructure of FA-GBFS based geopolymer paste with addition of silica fume

Geopolymers are attracting attention as a new green cementitious material. However, the severe early drying shrinkage deformation of geopolymers limits the use of geopolymer materials in construction projects. Therefore, this study investigates the effect of silica fume (SF) on the drying shrinkage behavior of geopolymer composite. Fly ash (FA) and granulated blast furnace slag (GBFS) were activated by a combination of sodium hydroxide and water glass solutions to produce geopolymer paste. The modification mechanism of SF content on the drying shrinkage and mechanical properties of FA-GBFS geopolymer paste was studied, as well as the important effect of SF on the internal geopolymerization process of geopolymer composite. The results indicate that the SF changes the binding energy and relative content of Si–O-T (T: Si or Al) structure and tetrahedral coordinated Al–OH bond in FA-GBFS geopolymer composite, delaying the early geopolymerization and calcium silicate hydration reaction in the geopolymer. It diminishes the polymerization degree of gel structure in the geopolymer, which also lowers the early strength of the geopolymer paste. In addition, when the SF content reaches 20%, it not only improves the 28d compressive strength of FA-GBFS geopolymer, but also greatly reduces the relative content of harmful pores inside the geopolymer, which reduces the early drying shrinkage strain by about 50%.

Surface Properties and Microstructures of Al-SBA-15 under Different Temperature Calcinations in Relation to Adsorption Performance

In this study, the calcination temperature was adjusted to influence the properties, including surface alumina types, microstructure, and surface acidity, and then to explore their association with the performance of As(V) adsorption after preparing aluminum-modified SBA-15 (Al-SBA-15x) by the incipient wetness impregnation method. The results showed that calcination promoted the formation of aluminum oxides with different coordination environments on SBA-15 carriers, resulting in different kinds of acid sites and Al–OH groups, which were the adsorption sites for As(V). However, with the increase in the calcination temperature, the total surface acidity on the Al-SBA-15x samples gradually decreased, and the dehydration and dehydroxylation reactions of aluminum oxides occurred, which reduced the Al–OH groups and changed the acid–base environment on the samples. Besides, high-temperature calcination caused a partial collapse of mesoporous channels, which was not conducive to dispersing the active adsorption centers on the surface and further reduced the effective utilization of active adsorption centers. Therefore, the adsorption capacity of an Al-SBA-15x adsorbent for As(V) decreased with the increase of the calcination temperature. Furthermore, kinetic models were used to investigate the relationship between the microstructure and adsorption processes. Finally, recycling tests were performed to demonstrate the reusability of Al-SBA-15x samples.

Designing Hybrid Lanthanum Stannate/Functionalized Halloysite Nanotubes as Electrode Material for Electrochemical Detection of 4-(Methylamino)phenol (Metol) in Environmental Samples

Electrochemical applications such as electrical conductivity, sensitivity, selectivity, cost-effectiveness, and sampling techniques of different forms of pyrochlore oxide have been a field of current interest. In this regard, pyrochlore structured lanthanum stannate nanoparticles (LSO) decorated with functionalized halloysite nanotubes (f-HNT) were prepared via hydrothermal followed by sonochemical synthesis. The obtained samples were characterized through various spectroscopic and microscopic methods to investigate the LSO@f-HNT structure and morphology. Electrocatalytic studies of LSO@f-HNT were performed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The beneficial response of LSO interacting with the hollow structured f-HNT groups of aluminol (Al–OH) and siloxane (Si–O–Si) enhances the electron transmission channel and active site size, both of which contribute to improved electrocatalytic performance. The fabricated sustainable LSO@f-HNT electrocatalyst exhibits outstanding selectivity and linear range (0.01–480 μM) with a detection limit of 2.1 nM and produces good recovery results (97.8–99.68%) under the optimized measurement conditions. This study discusses the design of the LSO@f-HNT composite and its application as an electrode material for the sensitive and focused electrochemical detection of hazardous Metol. This research demonstrates that LSO and f-HNT (LSO@f-HNT) is an excellent electrode material for electrochemical detection of Metol in real-world samples.

Insights on the dissolution of water in an albite melt at high pressures and temperatures from a direct structural analysis

The water dissolution mechanism in silicate melts under high pressures is not well understood. Here we present the first direct structure investigation of a water-saturated albite melt to monitor the interactions between water and the network structure of silicate melt at the molecular level. In situ high-energy X-ray diffraction was carried out on the NaAlSi3O8-H2O system at 800 °C and 300 MPa, at the Advanced Photon Source synchrotron facility. The analysis of the X-ray diffraction data was augmented with classical Molecular Dynamics simulations of a hydrous albite melt, incorporating accurate water-based interactions. The results show that metal–oxygen bond breaking at the bridging sites occurs overwhelmingly at the Si site upon reaction with H2O, with subsequent Si–OH bond formation and negligible Al–OH formation. Furthermore, we see no evidence for the dissociation of the Al3+ ion from the network structure upon breaking of the Si–O bond in the hydrous albite melt. The results also indicate that the Na+ ion is an active participant in the modifications of the silicate network structure of the albite melt upon water dissolution at high P–T conditions. We do not find evidence for the Na+ ion dissociating from the network structure upon depolymerization and subsequent formation of NaOH complexes. Instead, our results show that the Na+ ion persists as a structure modifier with a shift away from Na–BO bonding to an increase in the extent of Na-NBO bonding, in parallel with pronounced depolymerization of the network. Our MD simulations show that the Si–O and Al–O bond lengths are expanded by about 6% in the hydrous albite melt compared to those of the dry melt at high P–T conditions. The changes in the network silicate structure of a hydrous albite melt at high pressure and temperature, as revealed in this study, must be considered in the advancement of water dissolution models of hydrous granitic (or alkali aluminosilicate) melts.