Agglomeration Of Particles Research Articles

Sustainable Stabilization of Cadmium (Cd)-Contaminated Soil with Biochar-Cement: Evaluation of Strength, Leachability, Microstructural Characteristics, and Stabilization Mechanism

ABSTRACT To facilitate the solid waste reuse of cadmium (Cd)-contaminated soil and biochar and reduce the high emission of cement materials, we employed biochar-cement composite stabilizer to remedy Cd-contaminated soil. We assessed the effects of the biochar-cement composite stabilizer dosage and curing time on stabilized soil strength by using unconfined compressive strength (UCS) tests, leaching concentration and stabilization rate in Cd-contaminated soil stabilized by biochar-cement by using toxicity characteristic leaching procedure, and mechanism of change in strength and leaching characteristics by using scanning electron microscopy and X-ray diffraction. The research results demonstrate that biochar addition to cement-stabilized soil promoted cement hydration reaction and increased particle agglomeration. A low dosage of biochar improved stabilization effects. The optimal biochar dosage was 5%, which enhanced the early growth speed of the UCS. More cement improved the stabilized soil’s UCS. At a 5% cement dosage, adding biochar significantly reduced Cd leaching concentration, and improved the stabilization rate. At a 10% cement dosage, the biochar-cement composite stabilized soil’s stabilization rate was >99.8%. Calcium silicate hydrate, calcium aluminate hydrate, and ettringite were the main products of biochar-cement stabilized soil that filled soil and biochar pores; these substances encapsulated, adsorbed, or exchanged ions of Cd2+, achieving stabilization effects.

Chemical characterization of pellet stove ashes: Elemental fractionation of ashes results in volatile particles with high concentrations of cadmium and lead

Use of wood-based biomass for home heating has increased as a more sustainable and economical alternative to fossil fuel heating sources. However, concerns remain regarding particulate emissions and potential human health effects. Pellet stoves are very efficient combustion sources but still emit high particle numbers of nanoparticles into the environment and generate ash within the stove that could be an exposure source during cleaning. In this study we chemically characterize pellet ash collected from zones (upper and lower) from three stoves and determine the chemical composition of room air during cleaning events. Ash was acid digested using reverse aqua regia and microwave digestion and analyzed by ICP-MS. Indoor air was sampled using impingers before and during stove cleaning to assess ultrafine particulate release and exposure. Within the pellet stove different fractions of ash could be identified by color and macro-scale morphology. Ash fractions collected lower in the stove were predominantly calcium-based, 25 % by weight, and high in refractory trace elements, Fe, Cr, Mn and Ni. In contrast, ash collected higher in the stove was predominantly K and S based (25 and 5 % respectively) and had high concentrations of volatile elements Zn (0.4 %), Cd and Pb. Maximum Cd and Pb ash concentrations were 274 mg/kg and 807 mg/kg respectively corresponding to enrichment factors of 1581 and 870 compared to the respective pellets. Electron microscopy of the particles suggested that ash particles were agglomerates of smaller primary particles and EDS identified areas of high K and S concentration on the particles. Impinger studies of room air during cleaning showed an increase in K, S, Zn, Cd and Pb suggesting a mobilization of upper ash particles into room air upon stove cleaning.

A Study on the Motion Behavior of Metallic Contaminant Particles in Transformer Insulation Oil under Multiphysical Fields.

When using transformer insulation oil as a liquid dielectric, the oil is easily polluted by the solid particles generated in the operation of the transformer, and these metallic impurity particles have a significant impact on the insulation performance inside the power transformer. The force of the metal particles suspended in the flow insulation oil is multidimensional, which will lead to a change in the movement characteristics of the metal particles. Based on this, this study explored the motion rules of suspended metallic impurity particles in mobile insulating oil in different electric field environments and the influencing factors. A multiphysical field model of the solid-liquid two-phase flow of single-particle metallic impurity particles in mobile insulating oil was constructed using the dynamic analysis method, and the particles' motion characteristics in the oil in different electric field environments were simulated. The motion characteristics of metallic impurity particles under conditions of different particle sizes, oil flow velocities, and insulation oil qualities and influencing factors were analyzed to provide theoretical support for the detection of impurity particles in transformer insulation oil and enable accurate estimations of the location of equipment faults. Our results show that there are obvious differences in the trajectory of metallic impurity particles under different electric field distributions. The particles will move towards the region of high field intensity under an electric field, and the metallic impurity particles will not collide with the electrode under an AC field. When the electric field intensity and particle size increase, the trajectory of the metallic impurity particles between electrodes becomes denser, and the number of collisions between particles and electrodes and the motion speed both increase. Under the condition of a higher oil flow velocity, the number of collisions between metal particles and electrodes is reduced, which reduces the possibility of particle agglomeration. When the temperature of the insulation oil changes and the quality deteriorates, its dynamic viscosity changes. With a decrease in the dynamic viscosity of the insulation oil, the movement of the metallic impurity particles between the electrodes becomes denser, the collision times between the particles and electrodes increase, and the maximum motion speed of the particles increases.

Analysis of structural, dielectric, magnetic and impedance spectroscopy of ZnO/CuFe2O4 nanocomposites

The nanocomposites of ZnO/CuFe 2 O 4; abbreviated as (ZnO) x /(COF) 1-x (x; 10 ∼ 50 wt%) were prepared by powder mixing method. The x-ray diffraction pattern revealed the formation of nanocomposites (NCs) with inverse spinel structure of COF and hexagonal wurtzite structure of ZnO. The scanning electron microscope analysis depicts the nano-plates like morphology, non-homogenous mixing and agglomeration of particles. The dielectric properties and impedance spectroscopy of NCPs were measured by LCR meter in the frequency range of 1 kHz to 2 MHz. There is decrease in the real and imaginary parts of dielectric constant (ε′ and ε″) were observed with frequency, which is explained by Maxwell–Wagner’s polarization mechanism. The real and imaginary parts of impedance (Z′ and Z″) also show decreasing trend with frequency owing to increase in hopping of charge carriers that result in enhancement of a.c. conductivity (σ a.c ). The impedance spectroscopy shows a semicircular arc at higher frequency which is attributed to the conduction from grains. Finally, the vibrating sample magnetometer result showed the change in the magnetic nature of NCPs; as saturation magnetization (M s ) and coercivity (H c ) decreases substantially with incorporation of non-magnetic ZnO weight fractions.

Insight into microstructure evolution of in-situ ZrB2np/AA6111 composites with both excellent room and high temperature properties

With rapid development of aerospace and automobile, the service condition of structural components becomes increasingly harsh, diverse and high mechanical properties are urgently needed. In this work, an advanced in-situ ZrB2np/AA6111 composite with excellent room and high-temperature properties was prepared via Al-Zr-B reaction system. The microstructure revealed that ZrB2 nanoparticles with regular polygonal shapes ranged from 10 to 150 nm approximately, and a good α-Al/ZrB2 interface bonding was confirmed. The agglomeration of ZrB2 particles was significantly weakened during hot extrusion. Due to the inhibiting effect on dislocation motion and pinning effect on grain boundaries induced by ZrB2 particles, fine recrystallized grains were obtained in ZrB2/AA6111 composites after extrusion. Compared with AA6111 matrix alloy, the yield strength, ultimate tensile strength and elongation of AA6111-3ZrB2 composites at room temperature and 300 °C were increased by 18.9 %, 12.7 %, 50.0 % and 34.1 %, 22.4 %, 42.4 %, respectively. An excellent room and high-temperature strengthening effect was simultaneously achieved assisted by ZrB2 particles. The improvement of room-temperature properties was mainly owed to the Grain refinement and Orowan bypassing strengthening mechanisms. The good high-temperature properties mainly relied on the superior coarsening resistance of ZrB2 particles which could fully played the Orowan strengthening effect and well protected the grain boundaries at high temperature. This work provides a feasible approach to design high-performance aluminum alloys and is beneficial for the further development of modern industries.

Visual study of hydrate particles agglomeration and rolling characteristic in gas-oil-water phase using a flow loop

Natural gas hydrate blockage always leads to safety problems in oil and gas transportation pipelines. It is important to look for the characteristic of hydrate blockage process. The hydrate blockage was visually investigated under gas-oil-water multi-phase flow conditions in a flow loop in this study. The change of pressure drop with water conversion rate variations were detected. The hydrate particle movements were also observed in the visual pipes at different liquid loadings and water cuts. It was found that the hydrate particles may agglomerate and deposit with an obvious rolling process in low water cut conditions. The oil phase will accelerate particles agglomeration in the contact interface of oil, gas and water, and form a large number of flocculent hydrates. A theoretical hydrate particle rolling model was conducted to analysis the experiment results, and the hydrate particle velocity increases first and then decreases with the increase of particle diameter due to the comprehensive influence of van der Waals force and drag force. The results also confirmed the maximum of the pressure drop increased when the liquid loading increased. However, the hydrate formation and blockage speed also slow down due to small component of the gas phase in high liquid loading. In addition, comparing with 20 % and 80 % water cut, 50 % water cut has the fastest hydrate formation speed in different experimental conditions. Furthermore, the maximum water conversion rate increased with have a higher water cut. More hydrate will form in the condition, which will lead to the decrease of flow velocity in the pipeline.

Analysis of Structural Changes of pH-Thermo-Responsive Nanoparticles in Polymeric Hydrogels.

The pH- and thermo-responsive behavior of polymeric hydrogels MC-co-MA have been studied in detail using dynamic light scattering DLS, scanning electron microscopy SEM, nuclear magnetic resonance (1H NMR) and rheology to evaluate the conformational changes, swelling-shrinkage, stability, the ability to flow and the diffusion process of nanoparticles at several temperatures. Furthermore, polymeric systems functionalized with acrylic acid MC and acrylamide MA were subjected to a titration process with a calcium chloride CaCl2 solution to analyze its effect on the average particle diameter Dz, polymer structure and the intra- and intermolecular interactions in order to provide a responsive polymer network that can be used as a possible nanocarrier for drug delivery with several benefits. The results confirmed that the structural changes in the sensitive hydrogels are highly dependent on the corresponding critical solution temperature CST of the carboxylic (-COOH) and amide (-CONH2) functional groups and the influence of calcium ions Ca2+ on the formation or breaking of hydrogen bonds, as well as the decrease in electrostatic repulsions generated between the polymer chains contributing to a particle agglomeration phenomenon. The temperature leads to a re-arrangement of the polymer chains, affecting the viscoelastic properties of the hydrogels. In addition, the diffusion coefficients D of nanoparticles were evaluated, showing a closeness among with the morphology, shape, size and temperature, resulting in slower diffusions for larger particles size and, conversely, the diffusion in the medium increasing as the polymer size is reduced. Therefore, the hydrogels exhibited a remarkable response to pH and temperature variations in the environment. During this research, the functionality and behavior of the polymeric nanoparticles were observed under different analysis conditions, which revealed notable structural changes and further demonstrated the nanoparticles promising high potential for drug delivery applications. Hence, these results have sparked significant interest in various scientific, industrial and technological fields.

Numerical simulation of sulfur particle agglomeration at bends of high sulfur natural gas gathering pipelines based on Euler–PBM coupling

Sulfur deposition can result in an increase in the wall thickness of high-sulfur natural gas gathering pipelines, leading to issues like unstable pipeline flow. It is crucial to reveal the aggregation of sulfur particles at key locations of high-sulfur natural gas gathering pipelines to predict the location and amount of sulfur deposition in the pipelines. In this paper, the Euler–PBM (Population balance model) coupling is used to establish a numerical simulation model of gas–solid two-phase pipe flow accompanied by sulfur particle agglomeration in the pipe bends, focusing on the influence of sulfur particle volume fraction, pipe inclination angle and inlet flow velocity on sulfur particles agglomeration behavior. The results show that the sulfur particles have a significant agglomeration effect at the bend of the collecting pipeline, and the agglomeration growth occurs to different degrees throughout the bend, and the main area of sulfur particles agglomeration is near the top wall of the pipeline, followed by other areas near the wall of the pipeline. When the inlet volume fraction of sulfur particles was increased from 0.05 to 0.25%, and the inclination angle of the pipe was increased from 30° to 90°, the distribution range of sulfur particle size after agglomeration became wider, and the maximum size of sulfur particles was 187.56 μm, and the effect of sulfur particle agglomeration was enhanced; the inlet flow rate was increased from 3.0 to 9.0 m/s, and the reduction range of sulfur particle size after agglomeration was 5.68–9.87 μm. The maximum particle size of sulfur particles also decreased, and the effect of sulfur particle agglomeration was weakened.

Green Synthesis of Silver Nanoparticles Using Cashew Nutshell Liquid (CNSL): Characterization and Methylene Blue Removal Studies.

In this work, silver nanoparticles (AgNPs) were synthesized from cashew nutshell liquid (CNSL) by varying the concentration of silver ions and the pH of the CNSL extract. The synthesized AgNPs were further characterized to study their surface, structural, and morphological properties and tested for the removal of methylene blue (MB) dye. The results of this study showed that depending on the conditions, particles of various sizes, ranging from 1 to 60 nm, and different degrees of stabilization and agglomeration were produced. The concentration of silver ions equal to 3 mM and the pH of the extract of ~4.5 (AgNP3) resulted in the most efficient synthesis, where particles appeared to be highly stabilized and homogeneously distributed on the surface, exhibiting a small average particle size and a narrow particle size distribution (6.7 ± 6.5 nm). Such particles further showed the highest percent removal of MB, where up to 80% removal was recorded within the first 20 min. Higher concentrations of silver ions and higher pH of the extract resulted in substantial particle agglomeration and particles being over-capped by the CNSL biomolecules, respectively, which further negatively affected the ability of particles to remove MB. Finally, the fact that visible light showed no significant effect on the removal of MB, with the average removal rates found to be about the same as in the dark, suggests the strong catalytic nature of AgNPs, which facilitates the electron transfer reactions leading to MB reduction.

Performance and Microstructure of Grouting Materials Made from Shield Muck.

In response to the environmental pollution caused by transportation and accumulation of large-scale shield muck, the on-site reutilization of shield muck is an effective approach. This study explored the feasibility of silty clay muck to prepare muck grout. Through orthogonal experiments, the effects of cement, fly ash, shield muck, admixture, and the water-solid ratio on the fresh properties and mechanical properties of muck grout were studied. The performance prediction model was established Additionally, the intrinsic relationships between the compressive strength and microstructure of shield muck grouting materials were explored through multi-technology microstructural characterization. The results indicate that the content of muck and the water-solid ratio have a greater significant influence on the bleeding ratio, flowability, setting time, and volume shrinkage rate of muck grout compared to other factors. Cement has a greater significant influence on the compressive strength of muck grout than other factors. An optimal mix proportion (12% for cement, 18% for fly ash, 50% for muck, 0.465 for water-solid ratio, 19.5% for river sand, and 0.5% for bentonite) can produce grouting materials that meet performance requirements. The filling effect of cementitious substances and the particle agglomeration effect reduce the internal pores of grouting materials, improving their internal structure and significantly enhancing their compressive strength. Utilizing shield muck as a raw material for shield synchronous grouting is feasible.

Hydrothermal synthesis of SnO2/MoO3-x/rGO ternary nanocomposites as a high-performance anode for lithium ion batteries

The theoretical specific capacity of tin dioxide (SnO2) as a lithium-ion batteries (LIBs) anode material is up to 1494 mAh·g−1, far exceeding that of graphite. However, the low conductivity, volume expansion, crushing failure and particles agglomeration during charge/discharge cycles limit its application in LIBs. In this work, the SnO2/MoO3-x/rGO composite material was synthesized by one-step hydrothermal method, with SnO2 and amorphous MoO3-x tightly and uniformly anchored at the surface of reduced graphene oxide (rGO). The results of structural characterization and electrochemical performance evaluation show that amorphous MoO3-x can increase the reactive active sites, inhibit Sn particles aggregation, and promote the reversible reaction of SnO2. rGO effectively improves the electrical conductivity of the composite and buffers the volume change of Li-Sn alloying/dealloying during cycles. In addition, due to introduction of MoO3-x and rGO a stable SEI film can be formed at the material's surface to improve the cycle stability. SnO2/MoO3-x/rGO exhibits excellent rate performance and cycle performance. When the rGO content is 10.9 wt%, the reversible capacity of the composite reach 813 mAh·g−1 after 800 cycles at current density of 1.0 A·g−1, and 450.6 mAh·g−1 after 1000 cycles at current density of 5.0 A·g−1, with the capacity retention rate of 96.9%.

One-pot in situ synthesis of ZIF particles to prepare thin-film nanocomposite membranes for CO2 separation

Mixed matrix membranes (MMMs) are more likely to break the Robeson upper bound because they combine the pros of both organic and inorganic membranes. However, in the conventional MMM preparation processes, multi-steps are normally needed and, in many cases, the particle agglomeration and consequent non-selective voids are unavoidable, resulting in poor carbon dioxide (CO2) separation performances. In addition, the agglomeration makes it challenging to fabricate thin-film nanocomposite (TFN) membranes. In this study, zeolitic imidazolate framework (ZIF)-8- and ZIF-67-based TFN membranes were fabricated via a facile one-pot in situ synthesis protocol. The ZIF particles were synthesized in the polymeric solution, then the TFN membranes were fabricated by a dip coating method. With a casting solution concentration of 1.5 wt.%, a selective layer with a thickness of ∼300 nm can be prepared on the porous polyacrylonitrile (PAN) support. The results of thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), Fourier Transform Infrared (FT-IR) spectroscopy, and X-ray diffraction (XRD) showed that ZIFs were successfully synthesized in the casting solution. At 35 °C and 2 bar, the membrane containing 5 wt.% ZIF-67 had a CO2 permeance of 223.35 gas permeation unit (GPU), which was 16.55 % higher than that of pure Pebax.

Composites electron transport layer of PVA-regulated SnO2 for high-efficiency stable perovskite solar cells

As a new and efficient solar cell, perovskite solar cell has attracted wide attention due to its excellent performance. The electron transport layer in perovskite solar cells has a significant impact on device performance. SnO2 films that can be prepared by solution method have become the first choice for electron transport layer due to their simple process and excellent performance. However, the defects in SnO2 thin films and non-radiative recombination sites at the SnO2/Perovskite interface will lead to potential losses in the performance of photovoltaic devices. Therefore, in order to improve the interface loss and interface characteristics and prepare more efficient perovskite solar cells. In this work, a functional polymer, polyvinyl alcohol (PVA), is introduced to regulate the arrangement of SnO2 nanocrystals. The SnO2-PVA composite electron transport layer not only improves carrier transport, but also further affects the growth of perovskite films. PVA inhibits the agglomeration of tin dioxide particles by adding it to the aqueous solution of tin dioxide. Meanwhile, the oxygen vacancy defects in the SnO2 layer have also improved. Correspondingly, SnO2-PVA-based PSCs can be obtained a maximum efficiency of 23.73 %. Attributed to the strengthened interface binding and the improved perovskite crystallization process, the devices obtain good long-term stability, retaining 90 % of their initial performance after 1000 h operation at their maximum power point under 1 sun illumination.

Cost-Effective Microfabricated Silver-Based Paper Cathodes for High-Discharge-Rate Aluminum-Air Batteries

We report a cost-effective microfabricated silver-based air-cathode for high-discharge-rate aluminum-air batteries which are suitable for micro-drone applications. A challenge for batteries for aerial drones is that both high gravimetric energy density and power density are required for extended operation. While air batteries can address the energy density issue, achieving high power density necessitates high loadings of expensive catalytic materials such as platinum (Pt), which can constitute over 99% of the cost in commercial air batteries. [1] Building upon prior research that studied the power performance of an aluminum-air battery (AAB) system with a silver-based cathode, this study further explores the influence of silver (Ag) sputtering conditions and Ag loadings on AAB power performance. [2]The power performance of AAB is significantly influenced by both air flux through the air cathode and electrochemically active catalyst surface area ratio (ECSA). The ECSA is the ratio of the electrochemically active catalyst surface area to its cathode area. Sputtered Ag cathodes with catalyst loadings ranging from 0.03 mg-Ag/cm2 to 0.3 mg-Ag/cm2 consistently show high porosity, indicating good air flux for the microfabricated cathode. Increasing the loading of the sputtered Ag catalyst further can lead to particle agglomeration. To improve power performance and ECSA, a silver-copper (AgCu) co-sputtering technique has been developed, significantly increasing the surface area and power performance.Figure 1 shows cathodes with Ag loadings ranging from 0.038 mg-Ag/cm2 to 0.267 mg-Ag/cm2 under two silver sputtering conditions: 400W+5mTorr and 100W+10mTorr. Within the examined range, the latter sputtering condition shows superior power performance compared to the former. For Ag loadings exceeding 0.1 mg-Ag/cm2, both conditions show decreasing power performance as Ag loading increases, and the 100W+10mTorr curve shows a maximum power at 0.088 mg-Ag/cm2. Figure 2 shows SEM images of 0.038 mg-Ag/cm2, 0.088 mg-Ag/cm2, and 0.19 mg-Ag/cm2 films, using the 100W+10mTorr sputtering condition. Ag particle size increases with higher Ag loading, which can result from particle agglomeration. Figure 3 shows the catalyst layer porosity and the ECSA calculated from the SEM images. All samples show porosity over 90%, indicating good air flux for the microfabricated Ag cathode. The trend of ECSA for different Ag loading correlates well with the power performance, suggesting that the power performance of the microfabricated Ag cathode primarily depends on the ECSA.Further enhancement of the ECSA through AgCu co-deposition is investigated, involving two parent alloy compositions (at%): Ag28Cu72 and Ag16Cu84. Following the co-sputtering, the parent alloy undergoes selective etching of Cu using hydrochloric acid (HCl). Figure 4 compares power performance between Ag28Cu72 and Ag16Cu84. Both curves exhibit an upward trend as the silver loading increases from 0.09 mg-Ag/cm2 to 0.4 mg-Ag/cm2, with Ag28Cu72 samples showing superior power performance. Figure 5 shows an SEM image of Ag28Cu72 parent alloy with 0.32 mg-Ag/cm2 loading after Cu etching, demonstrating that the ECSA increased to 47.52 while maintaining a high porosity of 90.2%. The peak power of Ag28Cu72 0.32 mg-Ag/cm2 sample is increased to 200 mW/cm2. By comparison, a 4mg-Pt/cm2 commercial cathode shows a peak power of 280 mW/cm2.Figure 6 compares the discharge performance of the 0.088 mg-Ag/cm2 cathode with a commercial 4 mg-Pt/cm2 cathode. Both cells can discharge under 1.1 Amp with a power density exceeding 500 W/kgbattery, a threshold sufficient to lift a quadrotor drone. [3] Battery weight encompasses anode, cathode, electrolyte and battery packaging. The 0.088 mg-Ag/cm2 cathode shows a discharge power plateau above 600 W/kgbattery (86% of the 4 mg-Pt/cm2) and an energy density of 228 Wh/kgbattery when discharge power density exceeding 500 W/kgbattery (95% of the 4 mg-Pt/cm2). Remarkably, the material cost of the 0.088 mg-Ag/cm2 cathode is 5000 times less than the 4 mg-Pt/cm2 cathode.

(Digital Presentation) The Effects of Heat Treatment on Electroreduction of Tungsten (VI) Oxide

According to the classic scheme of the FFC Cambridge process, oxides of refractory metals are reduced in the solid state. Before electrolysis, oxides are shaped into cylindrical preforms and annealed at high-temperatures (~1000 °С). Therefore, the purpose of this study is to establish the effect of heat treatment of the initial sample of tungsten trioxide on its electrochemical reduction on a solid cathode in a CaCl2–NaCl melt.There are two types of tablets (preforms) were used for research: non-sintered (only compressed) WO3 and annealed at a temperature of 1000 °C. The surface of a pelletized tungsten trioxide sample without sintering is characterized by a uniform distribution of particles, shown in the SEM image (Fig. a). The particles agglomeration is characteristic for the sample WO3 after heat treatment (1000 °С) (Fig. b), which leads to a decrease in the area and an increase in the size of the voids. The unsintered sample has a larger surface area between the particles due to their dispersed state, which facilitates the penetration of the melt compared to the annealed sample.Electrochemical reduction of pressed WO3 samples (d=0.8 cm, h=0.15±0.20 cm, m=0.45–0.50 g) was carried out under galvanostatic conditions (800 °С) with using steel as the cathode and graphite as the anode. It was established that preliminary heat treatment of WO3 does not contribute to its electrochemical reduction. After applying 1.20 A·h of electricity, the porous granules of unsintered WO3 were completely transformed into metallic tungsten (W), which is shown in Fig. c, line 1. However, sintered samples after electrolysis (quantity of electricity is 1.42 A·h) reduced only partially: W – 74.1%; CaWO4 – 25.9% (Fig. c, line. 2).The results show that the reduction occurs more intensively in samples with more micropores, through which mass transfer occurs at the phase interface: tungsten compound to be reduced molten electrolyte mixture. That is why in the unsintered WO3 sample, the electrochemical reduction is faster. It can be assumed that the degree of reduction of WO3 on a solid electrode in CaCl2–NaCl also depends on its crystal structure. The annealed sample (tetragonal structure) is less susceptible to electrochemical reduction compared to the unannealed sample of tungsten trioxide (monoclinic structure). This is due to the fact that tetragonal WO3 (above 740 °C) is resistant to chemical attack, a poor conductor of electricity and has a low surface area. Monoclinic WO3 (from 17 to 330 °C) is more reactive, a better conductor of electricity and has a higher surface area. Figure 1

Microstructure-Aware Mesoscale Modeling of Chemomechanical Stress Evolution during Cycling in Solid Electrolyte-Cathode Composite

The volume change of cathode active materials during charge-discharge cycling is responsible for the capacity fading of all-solid-state Li batteries due to mechanical degradation in the cathode such as delamination and crack formation. Many strategies to alleviate the chemomechanical stress buildup have been proposed in experiments but rationale of the stress release mechanisms at the mesoscale remain elusive. In this presentation, we present a microstructure-aware mesoscale model to quantitatively predict the stress distribution during cycling in a secondary particle agglomerate of the cathode active material embedded within a solid electrolyte matrix, taking the LiCoO2-Li7La3Zr2O12 (LCO-LLZO) as a model system. We find that the mechanical stress hotspots develop at different stages within the grain boundaries of the LCO agglomerate and the LCO-LLZO interfaces. We investigate the influences of microstructural morphology (columnar versus equiaxial), grain orientations (textured versus random), mechanical properties at the grain boundaries and heterogeneous interfaces, and anisotropy of chemical expansion on the stress hotspot evolution and provide optimal mitigation strategies. The theoretical results can help gain mechanistic understanding on cathode degradation and inform guidelines for experimental design of mechanically optimized cathode materials for long-life solid-state batteries.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and 22-ERD-043.

Consolidation performance and mechanism of composite dust suppressant based on graft modification

AbstractTo solve the severe coal dust pollution and dust hazards in underground coal mines, this study utilized graft copolymerization modification technology and compound technology to develop a mining composite consolidation dust suppressant. On this basis, analysis of its consolidation wettability and dust suppression mechanism was conducted through characterization tests and molecular dynamics simulation methods. The results show that polyacrylamide (PAM) had been successfully grafted onto the soybean protein isolate (SPI) molecule, and form a SPI‐PAM complex. After the dust suppressant acted on the coal dust surface, it utilized its wealthy hydrophilic groups, for the adsorption of water molecules and the positive amide group for binding to produce a large area of agglomeration of coal dust particles at the interface, exhibiting good wetting and consolidation into a shell. At the same time, molecular dynamic simulation verified that the diffusivity of water molecules in the dust suppressant‐coal system was 0.30Å2/ps, decreased by 43.3%, and the interaction energy with coal molecules was −200.27 kcal/mol, absolute value increased by 41.35%, which made the dust suppressant molecules more easily adsorb and agglomerate on the surface, demonstrated an excellent solidification and dust suppression effect.

Study on the adsorption efficiency and mechanism of Sb(V) in aqueous solutions using enhanced surfactant-modified iron-calcium composite

The presence of Sb(V) in aqueous solutions poses a significant threat to the surrounding environment, and current treatment methods are inadequate. In this study, a magnetic surfactant (CTAB)-modified iron-calcium composite (CTAB-IC) was successfully synthesized using iron-calcium composite as the base material. This novel composite was used for the efficient removal of Sb(V) from textile wastewater solutions. Characterization analyses revealed that the CTAB-IC material exhibits a rich long-prismatic structure and superparamagnetic properties, classifying it as a soft magnetic material. Post-adsorption particle agglomerates were found to comprise Ca, S, and O. Sequential batch experiments demonstrated a maximum adsorption capacity of 54.05 mg/g, with adsorption kinetics data fitting the pseudo-second-order model. The intraparticle diffusion model indicated the presence of multiple diffusion steps during the adsorption process. Additionally, the adsorption of Sb(V) by CTAB-IC was identified as a heterogeneous surface adsorption process, best described by the Freundlich model. The primary adsorption mechanisms involved the formation of surface Ca-O-Sb complexes and inner-sphere Fe-O-Sb complexes, as well as amorphous surface precipitation and electrostatic adsorption. Notably, the treatment of textile wastewater often results in iron-calcium-rich sludge, which is challenging to manage and valorize. This study explored the potential for resource recycling by utilizing CTAB to harness the Fe elements in textile wastewater sludge, thereby promoting waste-to-resource conversion.

Comparative study of microwave-assisted and hydrothermal hydroxyapatite synthesis from neutralization slag: Optimization, energy, and adsorption

The study proposes the utilization of microwave-assisted methods for converting neutralization slag (NS) into hydroxyapatite (HAP), offering an alternative to the conventional hydrothermal method. The microwave-assisted approach addresses the challenges encountered in hydrothermal reactions, such as particle agglomeration, reduced specific surface area, prolonged reaction time, high temperature requirements, and inadequate saturation adsorption capacity. By employing the response surface methodology with a Box-Behnken design, the study found that the microwave-assisted method significantly reduced the synthesis time from 90 to 25 min and the temperature from 120 °C to 56 °C. Furthermore, the microwave method consumed only 1/43 of the energy utilized in hydrothermal synthesis. To assess the performance of the synthesized HAP, various detection methods were utilized, including XRD, SEM-EDS, FTIR, Zeta potential, and ICP, which analyzed the crystal structure, crystallinity, morphology, chemical composition, and surface charge of HAP. The BET method was used to measure the specific surface area, further confirming the successful synthesis of HAP. The HAP synthesized through this microwave-assisted method exhibited a saturation adsorption capacity of up to 98.4 mg/g of fluoride ions from vanadium industrial raffinate. This study demonstrates that the microwave-assisted method provides a viable solution for reducing energy consumption and enhancing HAP synthesis efficiency for wastewater treatment in the vanadium industry.

Interfacial engineering and defect passivation of SnO2 through agmatine sulfate in carbon-based perovskite solar cells

Electron transport layer has always played a crucial role in the performance of the perovskite solar cells (PSCs). Particularly, SnO2-based PSC has sparked considerable interest due to its superior properties. Even with such remarkable properties, certain challenges persist such as agglomeration of SnO2 particles which can lead to interfacial defects and poor morphology. To solve this problem, Agmatine Sulfate (AGTS) has been introduced as an interfacial modification agent which with the help of its active functional group including amide (-NH2) and hydroxyl (OH) has allowed to facilitate the interaction at the interface between SnO2 and perovskite. The interaction facilitates the growth of perovskite crystals while tuning the energy levels which has boosted the charge transfer capability of the layer. All these improvements in the properties have led to enhanced power conversion efficiency (PCE) from 11.17 % to 15.20 % for the encapsulated device. Furthermore, the modification also improved the long-term stability of the device as the AGTS-modified devices retained 87 % of their performance at 15–25 °C with humidity levels between 10 and 20 % for over a period of 31 days. Finally, the devices prepared with the AGTS also showed repeatability in their performance while boosting the overall performance of carbon-based PSCs (C–PSCs) and indicating a novel approach to not only increase but also accelerate the commercialization of C-PSC.