Changes In Particle Morphology Research Articles

Surgical dissection of ignition behavior of aluminum nanoparticles using molecular dynamics

Aluminum nanoparticles (ANPs) show great promise in energy technology, yet their atomic behavior during ignition remains a puzzle. This study provides insights into atomic migration processes within ANPs of different chemical layers during ignition and combustion, inspired by surgical peeling techniques. The research reveals that cavity formation in ANPs is inevitable due to disparities in atomic migration rates between core and surface areas, with core aluminum atoms experiencing sudden and significant stress alterations crucial for cavity formation. A linear trend in atom counts across radial layers correlates with particle geometry, influencing reactivity and morphological changes. The proposed Bond Environment Change (BEC) analysis reveals that oxygen atoms in the ANP shell undergo a three-phase evolution: intensive bonding, gradual relaxation, and stable configuration, reflecting the dynamic transformation of the oxide layer during the reaction process. While this research provides a deeper understanding of ANP ignition and combustion mechanisms, it may serve as a reference for refining ANP synthesis and guiding further inquiries in the field of nanoparticle-based energy technologies.

Preparation and release pattern study of long-term controlled release Blonanserin microspheres

To prepare a PLGA microsphere loaded with the antipsychotic Blonanserin without release leg period and released in a near-zero model for long time, in this study, 15 kDa and 75 kDa PLGA were chosen to be mixed with different ratios, and Blonanserin microspheres (Bn-MS) without significant differences in the particle size, drug loading capacity, and encapsulation rate were prepared by microfluidics. The release kinetic model was fitted to the release behavior by monitoring the changes in particle size and morphology during the Bn-MS release to investigate microspheres’ in vitro release pattern. The results showed that the addition of appropriate ratios of mixed molecular weights to Bn-MS could eliminate the release hysteresis period. When the ratio of 15 kDa and 75 kDa was 1:9 (F3), the Bn-MS had a low burst release rate, moderate release rate, no release hysteresis period, a long release period of up to 35 days, and a stable release pattern close to the zero level. The results of the release mechanism study indicated that the hybrid PLGA improved the release behavior of the microspheres by adjusting the dissolution degradation rate of Bn-MS, which in turn affected the release mechanism of the microspheres.

A multi-analytical approach to evaluate the removal efficiency of polystyrene nanoparticles in water treatment processes

The removal of nanoplastics (NP) from water using various treatment processes has gained significant attention recently. This study comprehensively characterizes the degradation of polystyrene nanoparticles (concentration: 200 ppm, diameter: 140 nm) through UVC irradiation. For the first time, we compared four analytical methods to monitor removal efficiency: Py-GCMS, UV–Visible spectroscopy, TOC, and Turbidity. Additionally, DLS, TEM, and SEC were used to understand changes in particle size, morphology, and molecular weight. Results showed that Py-GCMS overestimated the removal rate by a factor of 2 compared to Turbidity and UV–Visible measurements, which were in agreement. Furthermore, after 200 h of irradiation, the styrene signal disappears from the pyrogram, although the mineralization rate reaches only 50%, as determined by total organic carbon (TOC) analysis. The particle size decreased slowly, reaching 100 nm after 150 h, while a significant decrease in molecular weight indicated high chain-scission. These findings emphasize the importance of a multi-analytical approach to accurately assess NP removal efficiency and understand degradation mechanisms.

3D X-ray Tomography Analysis of Mg–Si–Zn Alloys for Biomedical Applications: Elucidating the Morphology of the MgZn Phase

Temporary metal implants, made from materials like titanium (Ti) or stainless steel, can cause metabolic issues, raise toxicity levels within the body, and negatively impact the patient’s long-term health. This necessitates a subsequent operation to extract these implants once the healing process is complete or when they are outgrown by the patient. In contrast, medical devices fabricated from absorbable alloys have the advantage of being biodegradable, allowing them to be naturally absorbed by the body once they have fulfilled their role in facilitating tissue healing. Among the various absorbable alloy systems studied, magnesium (Mg) alloys stand out due to their biocompatibility, mechanical properties, and corrosion behavior. The existing literature on absorbable Mg alloys highlights the effectiveness of silicon (Si) and zinc (Zn) additions in improving mechanical properties and controlling corrosion susceptibility; however, there is a lack of comprehensive quantitative morphological analysis of the intermetallic phases within these alloy systems. The quantification of the complex morphology of intermetallic particles is a challenging task and has significant implications for the micromechanical properties of the alloys. This study, therefore, aims to introduce a robust set of morphometric parameters for evaluating the morphology of intermetallic phases within two as-cast Mg alloys with Si and Zn additions. X-ray Computed Tomography (XCT) was used to capture the 3D tomographic data of the alloys, and a novel pair of morphological parameters (ratio of convex hull to particle volume and convex hull sphericity) was applied to the 3D tomographic data to assess the MgZn phase formed in the two alloys. In addition to the impact of composition, the effect of solidification rate on the morphological parameters was also studied. Furthermore, Scanning Electron Microscopy (SEM) and Energy-Dispersive Spectroscopy (EDS) were employed to gather detailed 2D microstructural and compositional information on the intermetallics. The comprehensive characterization reveals that the morphological complexity and size distribution of the MgZn phase are influenced by both compositional changes and the solidification rate. However, the change in MgZn intermetallic particle morphology with size was found to follow a predictable trend, which was relatively agnostic of the chosen casting conditions.

Title: Study of Structural Evolution of Silicon-Based Anodes in Lithium-Ion Batteries

The need for electrification across various sectors has led to increased demand for high-performance lithium-ion batteries (LIBs). Today’s commercial LIBs typically make use of a pure-graphite anode which offers long lifespans but a relatively meager capacity of 372 mAh/g. Silicon, by comparison, offers a theoretical capacity of 3600 mAh/g but generally suffers from short life spans due to numerous effects. Combining silicon and graphite active materials to form a composite anode can result in electrodes with improved capacities over pure-graphite systems and enhanced longevity over pure-silicon ones. However, introducing silicon to an otherwise stable graphite electrode can induce failure of the electrode partly due to the volumetric expansion/contraction that silicon experiences during lithiation/delithiation cycles. Understanding the morphological evolution of silicon particles in composite electrodes - particularly in a lithiated state - can yield a more comprehensive understanding of the interactions between the active materials which will contribute to the realization of anodes with improved capacities and lifespans. To date, characterizing lithiated silicon-containing anodes has been difficult owing to the reactivity of the lithiated materials and a lack of suitable methods to probe within an electrode’s bulk. In this work, we demonstrate recent successes in imaging lithiated silicon-composite and silicon oxide-composite electrodes via micro and nanoscale computed tomography (MicroCT, NanoCT) and electrochemical analysis to quantify (1) changes in particle size distributions over charge/discharge cycles, (2) lithium content in silicon particles as a function of depth from the electrode’s surface, (3) changes in particle morphology, and (4) electrode thickness. The development of this technique represents a significant step towards characterizing the physical behavior of silicon particles within electrodes without destroying the surrounding structures.

Protective Encapsulation of a Bioactive Compound in Starch-Polyethylene Glycol-Modified Microparticles: Degradation Analysis with Enzymes.

Starch is a promising polymer for creating novel microparticulate systems with superior biocompatibility and controlled drug delivery capabilities. In this study, we synthesized polyethylene glycol (PEG)-modified starch microparticles and encapsulated folic acid using a solvent-mediated acid-base precipitation method with magnetic stirring, which is a simple and effective method. To evaluate particle degradation, we simulated physiological conditions by employing an enzymatic degradation approach. Our results with FTIR and SEM confirmed the successful synthesis of starch-PEG microparticles encapsulating folic acid. The average size of starch microparticles encapsulating folic acid was 4.97 μm and increased to 6.01 μm upon modification with PEG. The microparticles were first exposed to amylase at pH 6.7 and pepsin at pH 1.5 at different incubation times at physiological temperature with shaking. Post-degradation analysis revealed changes in particle size and morphology, indicating effective enzymatic degradation. FTIR spectroscopy was used to assess the chemical composition before and after degradation. The initial FTIR spectra displayed characteristic peaks of starch, PEG, and folic acid, which showed decreased intensities after enzymatic degradation, suggesting alterations in chemical composition. These findings demonstrate the ongoing development of starch-PEG microparticles for controlled drug delivery and other biomedical applications and provide the basis for further exploration of PEG-starch as a versatile biomaterial for encapsulating bioactive compounds.

Study on the effect of sodium removal from citric acid pretreated red mud on the physical properties of red mud.

Red mud is a highly alkaline solid waste discharged from the alumina industry, and its high sodium content is the key factor limiting its wide utilization. Therefore, effective control of the "frosting" phenomenon during the application of red mud has received significant attention. In this study, the changes of particle size, phase, morphology, and pore size of red mud after sodium removal with different amounts of citric acid pretreatment were investigated. The single-factor experiment shows that the Na+ leaching rate is 86.33% under a citric acid dosage of 15%, liquid-to-solid ratio of 7mL/g, leaching temperature of 80°C, stirring speed of 300rpm, and leaching time of 10min. The leachate is characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area analysis. The results reveal that Na+ mainly exists in a combined state in the form of cancrinite. With the increase of citric acid dosage, red mud agglomerates, calcite, and cancrinite are dissolved, and new phases such as calcium oxalate and magnesium aluminum hydroxide are formed. The specific surface area, pore volume, and pore diameter show irregular changes with the increase in the citric acid dosage. Citric acid pretreatment can effectively reduce the sodium content in red mud, the treatment cost of leaching solution is low, and the leaching residue is neutral, which is helpful to promote the practical application of red mud.

Effect of process parameter on the flowability of nanocrystalline CoNiCrAlY powder synthesized by mechanical milling

The present study concerns understanding the effect of process parameters on the characteristics and flowability of nanocrystalline CoNiCrAlY powder synthesized by mechanical milling. Mechanical milling has been conducted in a planetary ball mill with tungsten carbide (WC) ball, with ball to powder ratio of 10:1 at 300 rpm speed, using 1% stearic acid and toluene as process control agent (PCA) with time varying from 10 h to 36 h. The synthesized nanocrystalline powder were characterized by Scanning Electron Microscopy, X-ray Diffraction technique, X-ray Photoelectron Spectroscopy, and Differential Scanning Calorimetry. Subsequently, flowability in terms of Hausner ratio was assessed by Tap Density Tester. Average particle size of the powder was found to decrease from 33 μm to 22 μm after 10 h of milling and further increases to 43 μm and 38 μm after 25 and 36 h of milling, respectively, in stearic acid medium. However, in toluene medium particle size continuously decreases from 33 μm to 9.7 μm with increasing milling time. The particle morphology changes from spherical to platelet shape at low milling hours in both of the media. After 25 h of milling, the shape of the particles is nearly spherical for stearic acid and irregular for toluene used as a PCA. Crystallize size was found to decrease with increasing milling time from 147 nm to 7.7 nm and to 6.4 nm in stearic acid and toluene media, respectively. There was presence of γ, γʹ, β, hcp-Co, Al2O3 and AlOOH phases on the powder particles milled in both the medium. The measured Hausner ratio of the powders was found to vary from 1.18 to 1.32 in stearic acid medium, and was found to increase with increasing milling time. On the other hand, in toluene media flowability decreases (Hausner ratio increases from 1.33 to 1.44) with increasing milling time.

Metal bond strength regulation enables large-scale synthesis of intermetallic nanocrystals for practical fuel cells.

Structurally ordered L10-PtM (M = Fe, Co, Ni and so on) intermetallic nanocrystals, benefiting from the chemically ordered structure and higher stability, are one of the best electrocatalysts used for fuel cells. However, their practical development is greatly plagued by the challenge that the high-temperature (>600 °C) annealing treatment necessary for realizing the ordered structure usually leads to severe particle sintering, morphology change and low ordering degree, which makes it very difficult for the gram-scale preparation of desirable PtM intermetallic nanocrystals with high Pt content for practical fuel cell applications. Here we report a new concept involving the low-melting-point-metal (M' = Sn, Ga, In)-induced bond strength weakening strategy to reduce Ea and promote the ordering process of PtM (M = Ni, Co, Fe, Cu and Zn) alloy catalysts for a higher ordering degree. We demonstrate that the introduction of M' can reduce the ordering temperature to extremely low temperatures (≤450 °C) and thus enable the preparation of high-Pt-content (≥40 wt%) L10-Pt-M-M' intermetallic nanocrystals as well as ten-gram-scale production. X-ray spectroscopy studies, in situ electron microscopy and theoretical calculations reveal the fundamental mechanism of the Sn-facilitated ordering process at low temperatures, which involves weakened bond strength and consequently reduced Ea via Sn doping, the formation and fast diffusion of low-coordinated surface free atoms, and subsequent L10 nucleation. The developed L10-Ga-PtNi/C catalysts display outstanding performance in H2-air fuel cells under both light- and heavy-duty vehicle conditions. Under the latter condition, the 40% L10-Pt50Ni35Ga15/C catalyst delivers a high current density of 1.67 A cm-2 at 0.7 V and retains 80% of the current density after extended 90,000 cycles, which exceeds the United States Department of Energy performance metrics and represents among the best cathodic electrocatalysts for practical proton-exchange membrane fuel cells.

In vitro digestion of microplastics in human digestive system: Insights into particle morphological changes and chemical leaching

Despite the well-reported occurrences and established pathways for microplastics (MPs) ingestion by humans, the eventual fate of these particles in the human gastrointestinal system is poorly understood. The present study tries to gain a better understanding of the fate of four common food-borne MPs, i.e. Polystyrene (PS), Polypropylene (PP), Low-density Polyethylene (LDPE), and Nylon, in a simulated in vitro human digestive system. Firstly, the changes in the physicochemical properties of 20–210 μm sized MPs as well as the leaching of chemicals were monitored using fluorescence microscopy, FTIR, and LC-QTOF-MS. Thereafter, the mass loss and morphological alterations in 3–4 mm sized MPs were observed after removing the organic matter. The interaction of PS and PP MPs with duodenal and bile juices manifested in a corona formation. The increase in surface roughness in PP MPs aligned with MP-enzyme dehydrogenation reactions and the addition of NO groups. A few fragments ranging from 30 to 250 μm, with negligible mass loss, were released during the MP digestion process. In addition, the leaching of compounds, e.g. capsi-amide, butanamide, and other plasticizers and monomers was also observed from MPs during digestion, and which may have the potential to accumulate and get absorbed by the digestive organs, and to subsequently impart toxic effects.

An Image-based method for evaluating changes in particle size and morphology distributions of aggregate materials after vibratory compaction test

Particle breakage and abrasion of aggregate materials can be induced by field compaction during construction, which adversely affects their mechanical properties. However, current compaction quality control testing does not evaluate changes in particle size distribution and particle morphology of aggregate materials due to the lack of fast and inexpensive testing methods. In this study, a modified watershed-based segmentation image analysis method and computational geometry algorithms were used to quickly quantify changes in particle size and morphology distributions of a large amount of contacting aggregate particles. The accuracy and required minimum sample size of the image analysis method were statistically evaluated. Compared to the conventional ASTM C136 aggregate sieve analysis test, the image analysis method conducted on a 40% sample size of the conventional method yielded less than 6% difference between the results, which can meet the ASTM C136 test repeatability criteria. In addition, demonstration tests were conducted to incorporate the image analysis method into a laboratory vibratory compaction test for evaluating the overall particle size and morphology changes of an aggregate material after compaction. Results indicate that the initial gradation and water content of the aggregate material can influence the particle breakage and abrasion characteristics of aggregate materials under compaction.

Improving Oral Bioavailability of Meloxicam: Development and Characterization of Solid Dispersions

This study investigated the development of a solid dispersion to improve the solubility and dissolution of meloxicam, a poorly water-soluble drug. Meloxicam is used to treat pain and inflammation in various conditions. The challenge was to enhance the drug's oral bioavailability by overcoming its low solubility. Two approaches were explored:
 
 1. Kneading method with Poloxamer 407: This method resulted in a formulation with significantly improved solubility compared to the pure drug.
 Solvent evaporation method with PVP K-30: While this method offered satisfactory solubility enhancement, it was not as effective as the kneading method with Poloxamer 407.Following the development of the optimized solid dispersion, a suspension formulation was prepared using various suspending agents. The optimized drug formula was then incorporated into the suspension mix. Characterization studies confirmed compatibility between the drug and excipients. FT-IR analysis showed no interaction between the drug and the carriers. Scanning electron microscopy (SEM) revealed a change in meloxicam particle morphology from crystalline to a more amorphous form, indicating a reduction in particle size and a potential explanation for the improved dissolution profile. The dissolution profile of the solid dispersion suspension prepared by the kneading method with Poloxamer 407 outperformed the one prepared with the solvent evaporation method and PVP K-30.This study demonstrates the effectiveness of the kneading method with Poloxamer 407 in developing a solid dispersion of meloxicam with enhanced solubility and dissolution. The optimized formulation exhibited good stability, acceptable drug content and release, and satisfactory rheological properties. This approach has the potential to improve the bioavailability of meloxicam and lead to a more effective oral dosage form.
 
 Keywords: Oral Bioavailability, Meloxicam:, Solid Dispersions , FT-IR analysis, SEM

Detachment of a Soluble Particle at the Slag-Argon Interface: CFD Study and Experimental Observations

The behavior of non-metallic inclusions at interfaces of high-temperature melt and molten slag affects the removal of inclusions and the consequent melt cleanness. This study presents real-time in situ observations on the behavior of an oxide particle in the vicinity of the slag-argon interface by means of high-temperature confocal scanning laser microscopy (HT-CSLM). On top of that, CFD simulations are conducted to investigate the underlying mechanisms of particle-interface interactions. In addition to revealing the particle motion process from the argon phase toward the slag, a significant particle morphology alteration associated with its dissolution in the slag is experimentally observed. Particularly, upon detachment from the slag-argon interface, the particle exhibits more dissolution at the near-interface area. By combining with numerical simulations, this study indicates that particle separation at the interface can be characterized as two stages. First, a short-term capillary force-driven motion stage happens until the particle initially settles at the interface. The settling position estimated by simulation shows good consistency with experimental measurement. Second, the particle takes a relatively long time to eventually detach from the interface, and this period is accompanied by particle dissolution. Investigations suggest that the concentration variation near the interface arising from particle dissolution triggers a Marangoni flow. This flow, in turn, enhances the local dissolution rate, consequently causing a significant particle morphology change that influences the detachment. This study provides new insight into the mechanism of inclusion removal through slag absorption in metallurgical processes. Both particle dynamics and dissolution kinetics, especially the effect of solutal Marangoni convection, are highlighted in detaching a small-scale particle from the fluid-fluid interface.

An investigation into proton conduction of ga doped boehmite based memristor with simulated synaptic behavior

Artificial synapses based on protonic memristor have great potential in constructing neural morphological computing system. However, further investigation is still required to understand the proton conduction mechanism of protonic memristors. Here, we present a new type of Ga doped boehmite based memristors with artificial synapse functionality, which can achieve variations in conductance levels by precise control of the Ga doping content. Compared with undoped boehmite, there is no obvious change in crystal structure, particle morphology and chemical bond doped with different of concentration Ga. The change in the electrical conductance is found to be a result of proton transfer, closely resembling what takes place in biological neurons. Furthermore, the first-principle density functional theory (DFT) calculation is conducted to elucidate the proton conduction mechanism and zig-zag-like pathways for proton transfer in the memristor was proposed. The results establish a precedent for tuning the proton transfer behaviour in memristor-based neural devices, thereby enhancing their practicality. It provides a novel approach for studying the resistance switching behavior in proton transfer-based memristors.

Morphological and Spectral Characterization of Lunar Regolith Breakdown due to Water Ice

Remote sensing observations of the Moon suggest that the lunar polar regolith environment is affected by several natural processes that may cause the regolith in these regions to become more porous and fine particulate. One of these processes may be the mechanical breakdown of regolith particles through the interaction of water ice and regolith by frost wedging. We present morphological and spectral analyses of high-fidelity lunar regolith simulants LHS-1 (lunar highlands simulant-1) and LMS-1 (lunar mare simulant-1) that have been exposed to varying concentrations of water ice (1, 10, and 30 wt%) over extended periods of time (1, 3, and 6 months) to evaluate the extent at which lunar regolith may be weathered by ice-regolith interactions in the Moon’s polar regions. To characterize changes in regolith particle morphology, we explored grain size and shape parameters with the CILAS ExpertShape suite and characterized the abundance and evolution of clinging fines with scanning electron microscopy and energy dispersive X-ray spectroscopy. Reflectance spectra were taken from 1.0–22.5 μm (444.4–10,000 cm−1) to characterize any differences in spectral features that may occur as a result of regolith breakdown. Both the morphological and spectral investigations display trends that show simulant particle degradation as a function of composition, increasing water concentration, and freezing time. Our study demonstrates that the lunar regolith is susceptible to mechanical breakdown in the presence of water ice and that water ice is likely a contributor to the weathering environment within permanently shadowed regions on the lunar surface.

Achievement of waste sludge deep dehydration under acidic conditions with polydimethyldiallylammonium chloride and ferric chloride: performance and mechanism.

The biological treatment of wastewater generates a substantial amount of waste sludge that requires dewatering before final disposal. Efficient sludge dewatering is essential to minimize storage and transportation costs. In this study, the sludge conditioners polydimethyldiallylammonium chloride (PDMDAAC) and ferric chloride (FeCl3) were sequentially dosed, and the pH was adjusted to 3. As a result, the sludge moisture content (MC) was reduced to 59.4%, achieving deep dewatering. After conditioning, the tightly bound extracellular polymeric substances (TB-EPS) were reduced from 34.5 to 10.2 mg g-1 VSS, with the majority of the reduced fractions being composed of protein (PN). In contrast, soluble EPS increased more than 8 times. Subsequent studies revealed that the decrease in PN from TB-EPS primarily involved tryptophan and tyrosine proteins, accompanied by a significant reduction in the N-H and C[double bond, length as m-dash]C absorption peaks. These results highlight the critical role of TB-EPS dissolution in achieving deep dehydration, with the N-H in PN was identified as the key group influencing sludge dewatering. Combined with the changes in sludge particle size and morphology, the dewatering mechanism can be summarized as follows: PDMDAAC dissolves TB-EPS, simultaneously disrupting the floc structure and refining the sludge. Subsequently, FeCl3 reconstructs these elements, forming larger particle sizes. Finally, hydrochloric acid reduces TB-EPS once again, releasing bound water. This study offers alternative methods and new insights for achieving deep dewatering of waste sludge.

Optical and structural behavior of hydrothermally synthesized ZnO nanoparticles at various temperatures with NaOH molar ratios

Small-sized ZnO nanoparticles were synthesized at varying hydrothermal reaction temperatures of 120 °C, 150 °C, 180 °C and NaOH molar ratios (1:2 and 1:8). As-prepared ZnO samples (i.e. Z1-120, Z1-150, Z1-180 and Z2-120, Z2-150, Z2-180) were characterized using XRD, FESEM, EDX, FTIR, and DRS. These tests showed that the fabricated samples were good in crystalline structure and hexagonal wurtzite, suggesting high purity. ZnO crystalline size samples varied from 16 nm to 35 nm as the reaction temperature and NaOH molar ratios increased. The particle morphology changes from a spherical shape to a flower-like rod shape and then to a cluster rod-like shape due to the difference in growth speed between the different crystallographic planes with rising temperature and molar ratios. Tauc's plot range predicted the band gap of all ZnO nanoparticle samples to be approximately 3.2 eV, lower than bulk ZnO's 3.37 eV, resulting in the absorption edge red-shifted in DRS spectra. The optical band gap energy (Eg) of all ZnO nanoparticles is hardly affected by reaction temperature and NaOH molar concentration, and quantum confinement has little effect. This study concluded that based on its small crystalline size (i.e. 16.67 nm) and flower-like shaped nanorod, the Z1-150 sample of ZnO nanoparticles prepared at 150 °C and 1:2 M ratios is suitable for further study. It has an absorption edge at 382 nm near the red region and an interplanar spacing (d) of 0.2471 nm at the plane (101). This study also reveals that zinc oxide nanoparticles' purpose despite their small size, may well recover application in water purification as a photo-catalyst/adsorbate and further used as nanocomposite.

Fate of ilmenite as oxygen carrier during 1 MWth chemical looping gasification of biogenic residues

Chemical looping gasification (CLG) is a novel gasification technology, allowing for the efficient conversion of different solid feedstocks (e.g. biogenic residues) into a high-calorific syngas. As in any chemical looping technology, the oxygen carrier (OC), transporting heat and oxygen from the air to the fuel reactor, is crucial in attaining high process efficiencies. To investigate the fate of the OC during CLG in an industrial environment, ilmenite samples, collected during >400 hours of chemical operation in 1 MWth scale using three different biomass feedstocks, were analyzed using different lab techniques. In doing so, changes in OC particle morphology and composition induced by CLG operation were determined. Moreover, the most important physical and chemical characteristics of the utilized OC were measured. The ensuing dataset allowed for an in-depth evaluation of the CLG technology in semi-industrial scale in terms of OC lifetime and durability. It was found that in the absence of agglomeration, the cycled OC exhibits an oxygen transport capacity of 2.6 wt.-%, a particle density of 3400 kg/m3 and particle diameters between 60 and 250 µm in steady-state conditions. Moreover, it was found that OC loss via particle attrition determines the lifetime of the OC inside the 1 MWth CLG system. On the other hand, feedstock-related agglomeration, observed during CLG operation with wheat straw, was shown to impede OC circulation between AR and FR and thus prevent efficient CLG operation. In summary, the present study thus not only highlights that generally long-term CLG operation in industry-like conditions is feasible, but also provides important insights into measures to improve OC lifetime and durability inside an industrial chemical looping system, such as an optimization of cyclone efficiency or tailored pre-treatment of the utilized feedstock.

Enhanced magnetoelectric coupling performance in CoFe2O4 @BaTiO3 multiferroic liquid by tuning the CoFe2O4 morphology

Multiferroic materials are identified as a newly emerging area of research because of their obvious magnetoelectric effects between ferroelectric and ferromagnetic orders. This paper uses the ball milling method to prepare CoFe2O4 @BaTiO3 (CFO@BTO) multiferroic liquids with different CoFe2O4 (CFO) particle morphologies. The settling stability and magnetoelectric properties of the CFO@BTO multiferroic liquids with different CFO particle morphologies have been systematically studied. XRD analysis confirmed that the crystal structure of the powders was consistent with that of standard cards, and the CFO powders exhibited irregular spherical shapes, well-dispersed rectangular shapes, and uniform nanowires. TEM images revealed a core-shell structure of the formed particles. The study found that as the CFO particle morphology changed from spherical to rectangular and then to nanowire, both the residual magnetization intensity (Mr) and saturation magnetization intensity (Ms) of both CFO powder and CFO@BTO composite powder increased gradually. The settling rate of the multiferroic liquids with spherical CFO morphology was observed to be 4.6% with good settling stability after resting for 48 h. The dielectric constant and dielectric loss showed similar trends in the presence and absence of magnetic fields. With the change in CFO particle morphology, the maximum polarization strength (Pmax), residual polarization strength (Pr), and coercivity field strength (Ec) of the multiferroic liquids gradually increased. The magnetoelectric coupling coefficient of the multiferroic liquids was found to be the largest when the CFO morphology was rectangular, measuring 23.93 V/(cm·Oe). The study provides insights into improving the magnetoelectric coupling effect of multiferroic materials and opens up new possibilities for further research in this area.

Iron as recyclable electrofuel: Effect on particle morphology from multiple combustion-regeneration cycles

This work describes the morphological and material changes in the iron powder during four regeneration-combustion cycles. The regeneration in H2 and combustion in air experiments were made in a fluidized bed (FB) and an entrained flow reactor (EFR), respectively. The average size of the iron oxide particles more than doubled between the first and fourth combustion cycles, and many of the particles were hollow. The regeneration step did not change the size of the particles but increased their porosity. A mechanism is proposed that describes the formation of large-diameter hollow particles which increases as a function of the regeneration-combustion cycles. The observed increase in particle size and the change in particle morphology complicates the iron fuel concept, as it leads to a degradation of the structural stability of the particle with time.