Volume Average Diameter Research Articles

Relation between bubble behaviors in spray sheet and bubbly flow inside an air-induction fan nozzle: A visualization study

The present study aims to elucidate the relationship between bubble behaviors in the spray sheet and internal bubbly flow of the air-induction nozzle. An experimental work was performed using the visualization technique. Effects of the air inlet position and spray pressure were investigated. The results show that compared with the bubbles inside the air-induction nozzle, bubbles in the spray sheet have smaller volume but larger average diameter. Disturbance propagates in the horizontal air-inlet segment. When the air inlet position shifts toward the nozzle outlet, overall bubble volume inside the nozzle decreases by about 56%, while in the spray sheet, the bubble volume decreases by about 77%. Bubble breakup causes a decrease in overall bubble volume as bubbles travel from the inner flow passage of the nozzle to the environment. The coalescence and compression of bubbles induce the increase in average bubble diameter. When the spray pressure increases from 0.1 to 0.3 MPa, both the total bubble volume and average bubble diameter increase.

Model for atomization droplet size and energy distribution ratio at the distal end of an electrostatic nozzle

Electrostatic atomization minimum quantity lubrication (EMQL) employs the synergistic effect of multiple physical fields to atomize minute quantities of lubricant. This innovative methodology is distinguished by its capacity to ameliorate the atomization attributes of the lubricant substantially, which subsequently augments the migratory and infiltration proficiency of the droplets within the complex and demanding milieu of the cutting zone. Compared with the traditional minimum quantity lubrication (MQL), the EMQL process is further complicated by the multiphysical field influences. The presence of multiple physical fields not only increases the complexity of the forces acting on the liquid film but also induces changes in the physical properties of the lubricant itself, thus making the analysis of atomization characteristics and energy distribution particularly challenging. To address this objective reality, the current study has conducted a meticulous measurement of the volume average diameter, size distribution span, and the percentage concentration of inhalable particles of the charged droplets at various intercept positions of the EMQL nozzle. A predictive model for the volume-averaged droplet size at the far end of the EMQL nozzle was established with the observed statistical value F of 825.2125, which indicates a high regression accuracy of the model. Furthermore, based on the changes in the potential energy of surface tension, the loss of kinetic energy of gas, and the electric field work at different nozzle orifice positions in the EMQL system, an energy distribution ratio model for EMQL was developed. The energy distribution ratio coefficients under operating conditions of 0.1 MPa air pressure and 0 to 40 kV voltage on the 20 mm cross-section ranged from 3.094‰ to 3.458‰, while all other operating conditions and cross-sections had energy distribution ratios below 2.06‰. This research is expected to act as a catalyst for the progression of EMQL by stimulating innovation in the sphere of precision manufacturing, providing theoretical foundations, and offering practical guidance for the further development of EMQL technology.

Effectiveness of Porous Durian Shell-based Activated Carbon for Methylene Blue Adsorption

In this study, durian shell-based activated carbon (DAC) was produced via chemical activation method by utilising durian shell and sulphuric acid (H2SO4) as the starting material and activating agent, respectively. The incorporation of H2SO4 in the DAC production process resulted an improvement in the surface properties and adsorption capacity of the produced DAC adsorbent. Field emission scanning electron microscopy analysis further showed that the produced DAC possessed a porous structure which was beneficial for dye adsorption application. Under operating conditions of 500°C and 3 hours carbonisation temperature and time, the Brunauer–Emmett–Teller (BET) surface area, total pore volume and BET average pore diameter were measured to be 242.03 m2/g, 0.028 cm3/g and 2.28 nm, respectively. The adsorption performance of the produced DAC was then investigated using methylene blue (MB) as the model adsorbate. The optimum MB dye removal and adsorption capacity were found to be 92.05% and 0.767 mg/g, respectively, with 0.6 g of DAC dosage, 10 ppm of initial MB dye concentration and 15 min of contact time.

Identification of Quantitative Trait Loci Controlling Root Morphological Traits in an Interspecific Soybean Population Using 2D Imagery Data.

Roots are the hidden and most important part of plants. They serve as stabilizers and channels for uptaking water and nutrients and play a crucial role in the growth and development of plants. Here, two-dimensional image data were used to identify quantitative trait loci (QTL) controlling root traits in an interspecific mapping population derived from a cross between wild soybean 'PI366121' and cultivar 'Williams 82'. A total of 2830 single-nucleotide polymorphisms were used for genotyping, constructing genetic linkage maps, and analyzing QTLs. Forty-two QTLs were identified on twelve chromosomes, twelve of which were identified as major QTLs, with a phenotypic variation range of 36.12% to 39.11% and a logarithm of odds value range of 12.01 to 17.35. Two significant QTL regions for the average diameter, root volume, and link average diameter root traits were detected on chromosomes 3 and 13, and both wild and cultivated soybeans contributed positive alleles. Six candidate genes, Glyma.03G027500 (transketolase/glycoaldehyde transferase), Glyma.03G014500 (dehydrogenases), Glyma.13G341500 (leucine-rich repeat receptor-like protein kinase), Glyma.13G341400 (AGC kinase family protein), Glyma.13G331900 (60S ribosomal protein), and Glyma.13G333100 (aquaporin transporter) showed higher expression in root tissues based on publicly available transcriptome data. These results will help breeders improve soybean genetic components and enhance soybean root morphological traits using desirable alleles from wild soybeans.

Green synthesis and high-performance fluoride ion removal using lanthanum-modulated MOF-808 (Zr)

In a water solution and with a low reaction temperature of 85 °C, the green preparation of lanthanum-modulated MOF-808 (Zr) was realized, the obtained La-MOF-808 have smaller grain size, larger specific surface area, higher pore volume and larger average pore diameter. When the molar ratio of La: Zr=1:1, 1L-MOF-808 had the best fluoride ion removal performance, and its maximum adsorption capacity for F- reached 101.4 mg/g, which was higher than that of the unmodulated MOF-808 and some other reported fluorine adsorbents. Meanwhile, the regeneration experiment demonstrated that even after five cycles, 1L-MOF-808 retained 73.8 % of its initial adsorption capacity, highlighting its commendable reusability. In addition, when 1L-MOF-808 was applied to actual fluorine-containing wastewater, with the fluoride ion concentration of 25.3 mg/L and an adsorbent dosage of 0.6 g/L, 1L-MOF-808 exhibited excellent resistance to anionic interference (SO42-, Cl-), the concentration of fluoride ions in effluent was lower than 10 mg/L, meeting the stipulations of fluoride ion discharge outlined in GB39371–2020. Further adsorption mechanism investigation revealed that 1L-MOF-808's affinity for F- was attributed to electrostatic interaction and ligand exchange. Overall, the as-synthesized 1L-MOF-808 not only presents an environmentally friendly approach to producing MOF materials without organic solvents but also develops a new strategy for the design of high-performance adsorbent for effectively removing fluoride ions from wastewater.

Effect of Na3AlF6 contents in refining flux on 3D characteristics of pore and mechanical properties of recycled Al-Mg-Si alloy

Fluoride is an essential and effective component in solid refining flux due to its ability to dissolve Al2O3. In this paper, the effects of Na3AlF6 content in refining flux on the pores and mechanical properties of recycled Al-Mg-Si alloy was investigated by tensile testing, scanning electron microscope (SEM) and Synchrotron radiation X-ray computed tomography (SRXCT). The results show that addition of Na3AlF6 transformed the shrinkage pores with large-sized irregular-shaped to highly spherical hydrogen pores, resulting in a significant reduction in pore volume fraction. When the refining flux with 5% Na3AlF6 is added to the melt, the volume fraction and average equivalent diameter of pores in the recycled alloy decreased by 84% and 23.2%, respectively, compared to those flux of without Na3AlF6. Furthermore, adding Na3AlF6 improves pore distribution uniformity while reducing the equivalent diameter of the largest pore by 83.7%. Although increasing Na3AlF6 content slightly increases pore equivalent diameter, it significantly reduces both larger pores (Equivalent diameter ≥20 μm) and their proportion. Moreover, the elongation of recycled Al gradually increases with higher Na3AlF6 content and reaches up to 21%, which is 40% higher than that without Na3AlF6. This improvement can be attributed primarily to reduced size and sphericity of shrinkage pores.

Mining elite loci and candidate genes for root morphology-related traits at the seedling stage by genome-wide association studies in upland cotton (Gossypium hirsutum L.)

Root system architecture plays an essential role in water and nutrient acquisition in plants, and it is significantly involved in plant adaptations to various environmental stresses. In this study, a panel of 242 cotton accessions was collected to investigate six root morphological traits at the seedling stage, including main root length (MRL), root fresh weight (RFW), total root length (TRL), root surface area (RSA), root volume (RV), and root average diameter (AvgD). The correlation analysis of the six root morphological traits revealed strong positive correlations of TRL with RSA, as well as RV with RSA and AvgD, whereas a significant negative correlation was found between TRL and AvgD. Subsequently, a genome-wide association study (GWAS) was performed using the root phenotypic and genotypic data reported previously for the 242 accessions using 56,010 single nucleotide polymorphisms (SNPs) from the CottonSNP80K array. A total of 41 quantitative trait loci (QTLs) were identified, including nine for MRL, six for RFW, nine for TRL, 12 for RSA, 12 for RV and two for AvgD. Among them, eight QTLs were repeatedly detected in two or more traits. Integrating these results with a transcriptome analysis, we identified 17 candidate genes with high transcript values of transcripts per million (TPM)≥30 in the roots. Furthermore, we functionally verified the candidate gene GH_D05G2106, which encodes a WPP domain protein 2 in root development. A virus-induced gene silencing (VIGS) assay showed that knocking down GH_D05G2106 significantly inhibited root development in cotton, indicating its positive role in root system architecture formation. Collectively, these results provide a theoretical basis and candidate genes for future studies on cotton root developmental biology and root-related cotton breeding.

Combined Application of Nitrogen and Phosphorus Promotes the Growth and Nutrient Accumulations of Cinnamomum camphora Container Seedlings

Combining the application of nitrogen and phosphorus is widely recognized as an effective measure to promote seedling growth. The purpose of this study was to investigate the effects of the combined application of nitrogen and phosphorus on the growth and nutrient status of C. camphora container seedlings. Exponential fertilization was applied to a range of fertilizers, including single nitrogen fertilizer, single phosphorus fertilizer, and combinations of nitrogen and phosphorus to C. camphora. Eight distinct fertilization levels of treatment (CK, N1, N2, N3, P, N1P, N2P, and N3P) were established. The height and ground diameter of the seedlings were determined periodically in each treatment group. Biomass, root system (including root length, root surface area, and root volume), and nutrient accumulation (content of soluble sugars, soluble proteins, and starch in the root system, stems, and leaves) were determined for each treatment group of seedlings. The N3P treatment (N: 9000 mg∙plant−1 + P: 6000 mg∙plant−1) had the most significant effect on the height and ground diameter of C. camphora container seedlings, while the N3 treatment (N: 9000 mg∙plant−1) proved to be the most beneficial for biomass accumulation among the eight different fertilizer levels. In addition, a single P fertilizer (P: 6000 mg∙plant−1) emerged as the most effective fertilizer for enhancing root morphology (root length, root surface area, root volume, and root average diameter) and accumulating nutrient composition (soluble sugar, soluble protein, and starch). Furthermore, it was discovered that a high level of nitrogen fertilization hindered the accumulation of nutrient composition in C. camphora container seedlings. Our comprehensive analysis revealed that nitrogen fertilizer promoted the morphological growth of C. camphora container seedlings, while phosphorus fertilizer proved to be the most beneficial for root growth and nutrient composition accumulation. Additionally, it was emphasized that controlling the quantity of nitrogen fertilizer is also a crucial measure.

CORRELATION BETWEEN AGING TIME PERIOD OF METAL PRECURSOR SOL – PHASE COMPOSITION AND TEXTURAL PROPERTIES OF ZIRCONIA NANOPOWDERS

This article investigates the effect of the time of aging of ZrO2 powders, obtained from zirconium butoxide sols, stabilized using complexating agents on the volume phase fractions tetragonal phase (T) and baddeleyite crystalographic phase (B), pore size distribution and pore volume. It was proved that the aging time period influences ratio between these two polymorphs of zirconia. The sample Zr3d possesses the largest content of baddeleyite phase having the greatest crystallites in comparison to another two powders. The increasing of aging period leads to a gradual increase in (101) peak intensity of T phase, while all the samples are microporous regardless of the aging time. The longest time aged sample possesses higher pore volume and higher average pore diameter than the other two powders. The physico-chemical features of the prepared ZrO2 nanosized powders could be beneficial as catalysts/photocatalysts in different catalytic reactions, corrosion inhibition particles, etc.

Arbuscular Mycorrhizal Fungi, Especially Rhizophagus intraradices as a Biostimulant, Improve Plant Growth and Root Columbin Levels in Tinospora sagittata

Tinospora sagittata is a columbin-rich medicinal plant, but its columbin levels are reduced under artificial cultivation conditions. The objective of this study was to analyze the effects of inoculations with Diversispora versiformis (Dv), Funneliformis mosseae (Fm), Rhizophagus intraradices (Ri), and mixed inoculation (Dv + Fm + Ri) (Mix) on growth performance, root morphology, leaf photosynthetic physiology, and root columbin levels in T. sagittata. These arbuscular mycorrhizal fungi (AMF) were able to colonize the roots, as evidenced by a root mycorrhizal colonization rate ranging from 17% to 48% and soil hyphal lengths ranging from 17.51 cm/g to 32.02 cm/g, with the Mix treatment being the greatest. AMF inoculations improved plant height (16–151%), leaf number (119–283%), shoot (37–211%), and root biomass (22–318%) to varying extents, with Ri and Mix treatments being the most prominent. AMF-treated plants presented relatively greater root total length, projected area, surface area, volume, and average diameter, especially those treated with Ri and Mix. AMF inoculations also significantly improved the leaf nitrogen balance index, transpiration rate, and stomatal conductance, while the photosynthesis rate and chlorophyll index varied by AMF species, along with a decrease in intercellular CO2 levels. Root columbin levels ranged from 0.524 mg/g to 5.389 mg/g, and AMF inoculation significantly increased root columbin levels by 228–928%, with Ri being the most significant. Root columbin levels were significantly positively correlated with soil hyphal length, root total length, root projected area, root surface area, root volume, and root average diameter, but not root AMF colonization rate. This study demonstrates for the first time that AMF, especially Ri, can be employed as a biostimulant to promote growth as well as root columbin levels in T. sagittata, where AMF-triggered improvement in root morphology is an important reason for promoting root columbin levels.

Synthesis of Autofluorescent Phenanthrene Microparticles via Emulsification: A Useful Synthetic Mimic for Polycyclic Aromatic Hydrocarbon-Based Cosmic Dust.

Phenanthrene is the simplest example of a polycyclic aromatic hydrocarbon (PAH). Herein, we exploit its relatively low melting point (101 °C) to prepare microparticles from molten phenanthrene droplets by conducting high-shear homogenization in a 3:1 water/ethylene glycol mixture at 105 °C using poly(N-vinylpyrrolidone) as a non-ionic polymeric emulsifier. Scanning electron microscopy studies confirm that this protocol produces polydisperse phenanthrene microparticles with a spherical morphology: laser diffraction studies indicate a volume-average diameter of 25 ± 21 μm. Such projectiles are fired into an aluminum foil target at 1.87 km s-1 using a two-stage light gas gun. Interestingly, the autofluorescence exhibited by phenanthrene aids analysis of the resulting impact craters. More specifically, it enables assessment of the spatial distribution of any surviving phenanthrene in the vicinity of each crater. Furthermore, these phenanthrene microparticles can be coated with an ultrathin overlayer of polypyrrole, which reduces their autofluorescence. In principle, such core-shell microparticles should be useful for assessing the extent of thermal ablation that is likely to occur when they are fired into aerogel targets. Accordingly, polypyrrole-coated microparticles were fired into an aerogel target at 2.07 km s-1. Intact microparticles were identified at the end of carrot tracks and their relatively weak autofluorescence suggests that thermal ablation during aerogel capture did not completely remove the polypyrrole overlayer. Thus, these new core-shell microparticles appear to be useful model projectiles for assessing the extent of thermal processing that can occur in such experiments, which have implications for the capture of intact PAH-based dust grains originating from cometary tails or from plumes emanating from icy satellites (e.g., Enceladus) in future space missions.

Atomization mechanism and machinability evaluation with electrically charged nanolubricant grinding of GH4169

Nanofluid minimum quantity lubrication (NMQL), which offers excellent economic and environmental benefits, has the greatest potential to replace traditional metal grinding with fluids. However, insufficient infiltration performance, poor atomization properties, and inferior controllability are found in pneumatic atomization minimum quantity lubrication (MQL), hindering the improvement of grinding performance. Electrostatic atomization MQL (EMQL) is expected to address the coexistence of grindability and sustainability through electrical charge empowerment. Nevertheless, studies addressing the effects and mechanisms of electrically charged nanolubricants in the grinding of nickel-based superalloys remain scarce. In this study, the atomization characteristics of EMQL are experimentally investigated, and results show that the droplet volume average diameter and diameter Rosin–Rammler distribution span of EMQL decreased by 7.1 % and 40.3 %, respectively, in comparison with those of MQL. Then, a series of grinding experiments on GH4169 with different cooling conditions are conducted. Results show that compared with those for MQL grinding, the coefficients of friction for EMQL and NMQL grinding decreased by 9.35 % and 15.62 %, the specific grinding energies decreased by 16.71 % and 29.06 %, and the values of surface roughness Sa decreased by 3.04 % and 14.33 %, respectively. The optimal combination of atomization method and medium for grinding GH4169 is EMQL and nanolubricant. Sa showed a 16.12 % decrease for the surface machined via the optimal combination compared with the surface machined via flooding. Last, to support the interpretation of the grinding outcomes, the antifriction mechanisms of electrically charged nanolubricants are analyzed in combination with the wetting, infiltration, and film-formation capabilities of droplets. The findings of this work are expected to provide experimental references for the surface integrity improvement of the nickel-based superalloy grinding process.

Charge Obtained by Electrodispersing Waste of the LS58-3 Alloy in Distilled Water

The purpose of this study was to conduct metallographic studies of the composition of the charge obtained by the method of electrodispersion of lead brass waste in distilled water.Methods. Waste electrodispersion of lead brass brand LS58-3 was carried out on an experimental setup. Metallographic studies of charge samples from LS58-3 alloy waste were performed using the equipment of FGBOU VO SWGU and NRU BelGU: the shape, size and structure of charge particles, as well as its granulometric composition.Results. On the basis of the conducted experimental studies aimed at studying the composition, structure and properties of the charge obtained from the waste of the LS58-3 alloy in distilled water, the high efficiency of using the electrodispersion technology is shown, which provides, at low power costs, the production of new copper-lead powders suitable for industrial use. materials. It is noted that the powder materials obtained by electroerosion of lead brass waste of grade LS58-3 in distilled water have the following characteristics: the geometric shape of the charge particles is mainly spherical; particle sizes from 0.45 to 29.63 microns; the volume average particle diameter is 7.1 μm.Conclusion. The research carried out will allow for a gradual transition to advanced production technologies and materials through the use of progressive, environmentally friendly, low-tonnage and waste-free technology of electroerosive dispersion in the production of new copper-lead powder materials from LS58-3 alloy waste.

Effect of oxygen-containing functional groups and pore structure characteristics of coal on the slurryability of coal wastewater slurry

The physical and chemical characteristic of coal have an important influence on the slurryability of coal wastewater slurry. In this paper, eight different coals are used to make coal wastewater slurry, and the effects of oxygen containing functional groups and pore structure characteristics of different coal samples on the slurryability are analyzed. Results show that (a) Coal with more oxygen-containing functional groups on surface have stronger hydrophilicity, higher surface activity and have stronger adsorption capacity for water molecules, this will lead to the reduction of free water and the increase of viscosity of the slurry. (b) Coal with larger BET specific surface area and pore volume and smaller average pore diameter have the stronger ability to adsorb and store water in coal wastewater slurry, thus the concentration of coal wastewater slurry prepared from these coal is low. The conclusion of this paper can provide reference for coal selection in the preparation of coal wastewater slurry.

H2/NH3 Addition Effects on Flame Characteristics and Soot Formation in Ethylene Inverse Diffusion Flame

Zero-carbon alternative fuels such as hydrogen and ammonia are gaining popularity. Blending these fuels with hydrocarbons is an intermediate approach to mitigate soot and carbon dioxide production. Recent studies have concentrated their attention to the effects of ammonia and hydrogen on the soot production of hydrocarbon fuels. It is still necessary to completely comprehend how this influence is dependent on the type of fuel and flame configuration. In this work, the effect of hydrogen and ammonia addition on soot production in ethylene laminar inverse diffusion flames (IDF) was numerically examined for the first time. The thermal, chemical, and combined effects of hydrogen and ammonia were assessed by fictitious species. The experimental results from the literature were used to validate the temperature and soot volume fraction profiles. Results indicated that the flame temperature and the production of radicals are promoted chemically by hydrogen addition but inhibited under the thermal effect of ammonia. The principal source of the reduction in OH-represented flame height, soot volume fraction, average diameter, and primary particle number density in the IDF is the thermal effect of additives, and hydrogen addition performs better than ammonia. The major and intermediate species, the aromatic hydrocarbons, and the soot formation or oxidation reaction rates are decreased mainly by the hydrogen and ammonia thermal effect while increased moderately by the chemical effect. Therein, the reduction in soot generation is mainly due to the polycyclic aromatic hydrocarbon condensation rate being slowed down by additives. The inhibition is attributed to the thermal effect of additions, and hydrogen behaves better than ammonia.

Mechanism and Experimental Study on Electrostatic Atomization Using Needle-Shaped Electrodes

The conventional pneumatic Minimum Quantity Lubrication (MQL), when not properly designed, may have poor atomization and insufficient wetting performance, resulting in higher oil mist concentration and poor film formation ability in the cutting zone. The intervention of an external electric field can change the atomization mechanism of microdroplets and enhance the lubrication and cooling capability of MQL. However, the mechanism of the effect of jet parameters on the atomization performance of Electrostatic Minimum Quantity Lubrication (EMQL) under the synergistic effect of multiple fields has not been fully analyzed. In this paper, based on the designed needle electrode charging nozzle, the atomization medium charging and atomization mechanisms are investigated, and a mathematical model of the volume average diameter of droplets (VAD) is established. Based on multi-parameter atomization experiments, the electrode conical jet atomization model is validated and the mechanism of the influence of jet parameters on the atomization characteristics is analyzed. The results show that the VAD is negatively correlated with air pressure and electrical. The atomization performance of the droplets was improved under the applied voltage condition, which was manifested by the obvious refinement of the VAD, with a maximum reduction of 34.67%, a maximum reduction of 20% in the droplet group size distribution span (R.S.), and a different degree of reduction in the percentage concentration of fine particulate matter. In addition, the model fitted well with the experimental values, with an overall error of about 10%.

The methyl blue adsorption performance and mechanism of NaX zeolite synthesized from Huadian oil shale ash

BackgroundAs a by-product of oil shale retorting process, oil shale ash would cause serious environmental problems. The similar composition to that of zeolites makes oil shale ash suitable to synthesize zeolites, which can be used to remove dyes from wastewater with low cost. This could provide not only an effective way for the potential utilization of oil shale ash but also a cheap raw material for the preparation of zeolites. It is of great significance to realize the win-win situation of environment and economic benefit of oil shale and dyeing industries. MethodsIn this work, NaX zeolite was synthesized successfully from Huadian oil shale ash by the alkaline fusion hydrothermal method and used to remove methyl blue. Significant findingsThe specific surface area, pore volume and BJH adsorption average pore diameter of the synthetic zeolite are 366.8672 m2/g, 0.208501 cm3/g and 7.0101 nm, respectively. Under the optimum conditions, the removal percentage of methyl blue could reach to 96.0%, and the synthetic zeolite has an excellent reusability. The existence of salts and salinity would influence the MB removal efficiency. The adsorption mechanism study indicates that electrostatic attraction, hydrogen bonds and pore diffusion facilitate the methyl blue adsorption on the synthetic NaX zeolite.

Prediction model of volume average diameter and analysis of atomization characteristics in electrostatic atomization minimum quantity lubrication

Minimum quantity lubrication (MQL) is a relatively efficient and clean alternative to flooding workpiece machining. Electrostatic atomization has the merits of small droplet diameter, high uniformity of droplet size, and strong coating, hence its superiority to pneumatic atomization. However, as the current research hotspot, the influence of jet parameters and electrical parameters on the average diameter of droplets is not clear. First, by observing the shape of the liquid film at the nozzle outlet, the influence law of air pressure and voltage on liquid film thickness (h) and transverse and longitudinal fluctuations are determined. Then, the mathematical model of charged droplet volume average diameter (VAD) is constructed based on three dimensions of the liquid film, namely its thickness, transverse wavelength (λh), and longitudinal wavelength (λz). The model results under different working conditions are obtained by numerical simulation. Comparisons of the model results with the experimental VAD of the droplet confirm the error of the mathematical model to be less than 10%. The droplet diameter distribution span value Rosin-Rammler distribution span (R.S) and percentage concentrations of PM10 (particle size of less than 10 µm)/PM2.5 (particle size of less than 2.5 µm) under different working conditions are further analyzed. The results show that electrostatic atomization not only reduces the diameter distribution span of atomized droplets but also significantly inhibits the formation of PM10 and PM2.5 fine-suspension droplets. When the air pressure is 0.3 MPa, and the voltage is 40 kV, the percentage concentrations of PM10 and PM2.5 can be reduced by 80.72% and 92.05%, respectively, compared with that under the pure pneumatic atomization condition at 0.3 MPa.

Monte-Carlo simulation of mass density field coupled dynamics for microstructural evolution of Fe-Cr binary alloys

The phase transformation kinetics and micro-structure evolutions of four different Fe-Cr binary alloys, i.e. Fe-Cr (12.8%), Fe-Cr (20.0%), Fe-Cr (30.0%) and Fe-Cr (40.0%) at 673 K, are investigated by using the kinetic Monte-Carlo simulation combined with spatial coarse-grained mass density field description. For all studied Fe-Cr alloys, it is found that the number density of Cr-rich precipitate undergoes a rather rapid increasing at the nucleation stage and then gradually decreases with the simulation time increasing in the coarsening stage during aging. Increasing the Cr concentration in Fe-Cr alloy can significantly reduce the duration of nucleation and the time interval between nucleation and coarsening. From the coarse-grained mass density field models of Cr-rich precipitates at different aging stages for the four Fe-Cr alloys, we discover that the Cr-rich phase shows the isolated spherical particle-like morphology for the aged Fe-Cr (12.8%) alloy, revealing the nucleation and growth (NG) mechanism. Meanwhile, the Cr-rich precipitates possess a characteristic three-dimensional interconnected microstructure, a signature of spinodal decomposition mechanism. Otherwise, the Cr-rich phase morphology in Fe-Cr (20.0%) exhibits the characteristics of both NG mechanism and SD mechanism. It is also found that the short-range order parameter of Cr atoms in Fe-Cr alloy is indeed very sensitive to the change of atomic structure at the early stage of aging or nucleation stage, which, however, is almost independent of the changing of morphology of Cr-precipitates in the later coarsening process. Finally, the phase transformation kinetics of Cr-rich precipitates during aging are analyzed by calculating the phase volume fraction, average diameter and number density, concluding that the Cr-rich phase growth kinetics in Fe-Cr (20.0%) alloy can be described by the well-known Lifshitz-Slyozov-Wagner law in the coarsening stage. However, the coarsening kinetics of Fe-Cr (12.8%), Fe-Cr (30.0%) and Fe-Cr (40.0%) alloys are not caused by the LSW mechanism.

Fabrication of Polyvinylpyrrolidone‐Stabilized Nano Zero‐Valent Iron Supported by Hydrophilic Biochar for Efficient Cr (VI) Removal from Groundwater

AbstractToday, eco‐friendly and cost‐effective nanomaterials are vital to ultimately removing contaminants from groundwater as an essential part of freshwater. In this study, polyvinylpyrrolidone (PVP)‐stabilized nano zero‐valent iron (nZVI) supported by hydrophilic wheat straw biochar (HWS) (PVP‐nZVI@HWS) was prepared and compared with the nZVI‐HWS sample for Cr (VI) removal from aqueous media. The morphology and functional group structure of PVP‐nZVI@HWS composites demonstrated that nZVI could be dispersed homogeneously on the hydrophilic biochar substrate by adding PVP (owing to a large number of −OH functional groups). Based on BET analysis, despite a minimal reduction in the surface area of the PVP‐nZVI@HWS hybrid material compared to the nZVI‐HWS sample (7.19 m2 g−1), the pore volume and adsorption average pore diameter increased. Superior reduction efficiency (99.63 % elimination in only 5 min) of 20 ppm Cr (VI) was achieved using the proposed hybrid material. Pseudo‐ second‐order kinetics (R2=1) and Langmuir isotherm models (R2=0.9407) were attained via the PVP‐nZVI@HWS (0.2 g L−1) under groundwater condition (sodium chloride solution at pH=3.2). In addition, on a large scale, the proposed hybrid material could reduce 97.22 % of Cr (VI) in 180 minutes from the water. The mechanism of catalytic and absorption behaviour for two catalysts was compared, and the investigations showed that absorption action for the nZVI‐HWS sample, and catalytic behaviour for the PVP‐nZVI@HWS hybrid material were predominant.