Decline In Particle Size Research Articles

The influence of different gums compared with surfactants as encapsulating stabilizers on the thermal, storage, and low-pH stability of chlorophyllin

Sodium copper chlorophyllin (SCC), with a higher stability and water solubility than chlorophyll, has limited applications in acidic products due to precipitation. We investigated the effect of pectin (PE), carboxymethyl cellulose (CMC), xanthan gum (XG), carrageenan gum (CG), gellan gum (GG), tragacanth gum (TG), gum Arabic (GA), and polysorbate 80 (PS80) on SCC stability in acidic model solutions (pH = 3.5). These stabilizers led to a significant reduction in particle size and zeta-potential compared to control sample. GA (33.3:1), PE (8:1), CMC (4:1), XG (1.33:1), and PS80 (0.67:1) stabilized SCC in acidic systems for 28 days. The FTIR analysis showed that mainly electrostatic and hydrogen bonds between SCC and stabilizers led to a substantial decline in particle size, improving SCC distribution and stability within acidic environment. Thus, XG and CMC could be effectively used for SCC stabilization under acidic solutions where applying PS80 surfactant is a health concern.

Testing of magnetic and dielectric traits of microwave plasma treated NiCuZn spinel ferrites for efficient energy storage and high-frequency applications

In this study, the dielectric, microstructural, and magnetic characteristics of NiCuZnFe2O4 ferrites, produced by an auto-ignition method, were tuned through microwave non-thermal plasma treatment. XRD analysis confirmed the cubic spinel structure with an average crystallite size of 47.7 nm. It was also witnessed that plasma treatment slightly increased the porosity of prepared samples. FTIR analysis confirmed the appearance of absorption bands in the range of 450–700 cm−1, which are assigned to spinel ferrites. The pristine spinel ferrite microstructures demonstrated sharp grain boundaries and agglomeration appeared in all specimens due to magnetic interactions. A slight decline in particle size in the plasma-treated sample was noticed in these investigations. VSM analysis revealed saturation magnetization of 31.70 emu/g and 53.20 emu/g for pristine ferrite and after 45 min of plasma treatment, respectively. Dielectric measurements demonstrated that plasma exposure significantly reduced the dielectric loss and improved the dielectric constant.

Physical Properties and Storage Stability of Buton Rock Asphalt Modified Asphalt.

Buton Rock Asphalt (BRA) refers to the natural rock asphalt natively produced on the Buton island of Indonesia. It is often used as a modifier to enhance the performance of asphaltpavement. However, the segregation of BRA in BRA-Modified Asphalt (BRA-MA) has restricted its application. This study aims to investigate how the particle size and content of BRA affect the physical properties and storage stability of BRA-MA. Penetration, softening point, viscosity, and viscosity-temperature susceptibility (VTS) were analyzed. The evaluation method of storage stability was discussed and determined. The segregation of BRA in BRA-MA of static storage and transportation process were simulated and tested. The results suggest that the softening point and viscosity were positively correlated to BRA content and inversely determined by particle size. Penetration, VTS, and ductility were reduced due to the decline in particle size and increment of BRA content. The index of segregation value based on viscosity difference showed better statistical and quantitative significances than the softening-point difference in evaluating the storage stability. The particle size and content of BRA are positively correlated to the segregation of BRA-MA. Both the storage temperature and time were positively correlated to the segregation of BRA-MA. We prove that the relationship between specific surface area and segregation are power functional. BRA-MA with BRA whose 50% particle sizes are lower than 13.6 μm showed low segregation in transportation.

Treatment of fracturing wastewater by anaerobic granular sludge: The short-term effect of salinity and its mechanism

The effects of salinity shock on the anaerobic treatment of fracturing wastewater regarding chemical oxygen demand (COD) removal performance, sludge characteristics and microbial community were investigated. Results showed COD removal efficiency decreased from 76.0% to 69.1%, 65.6%, 33.7% and 21.9% with the increase of salinity from 2.5 g/L to 10, 15, 25 and 45 g/L, respectively. The cumulative biogas production decreased by 13.8%–81.1% when salinity increased to 15–85 g/L. The increase of salinity led to the decline in particle size of granular sludge, and the activity of granular sludge, including SMA, coenzyme F420 and dehydrogenase, was inhibited significantly. Flow cytometry indicated the percentage of damaged cells in granular sludge gradually increased with the increase of salinity. Sequence analysis illustrated that microbial community structure in anaerobic digestion reactor was influenced by the salinity, high salinity reduced the diversity of archaea and decreased the abundance of methanogens, especially Methanosaeta.

Grindability Evaluation of Fragmented Clay Bricks for Performance Analysis of Cement Paste Incorporating Clay Brick Powder

.Milling treatments for evaluating grindability of pozzolanic materials using ball mill have been employed with limited research focused on fragmented clay bricks. Of great importance of the milling treatments are the milling times and sample masses. Moreover, the applications of grindability of Clay Brick Powder (CBP) in cement paste are found to be limited. In this paper, the effects of increasing milling time and increasing sample mass of fragmented clay bricks on fineness of resulting CBP were examined using ball milling and particle size distribution curves. The Scanning Electron Microscope (SEM) was implemented to characterise the morphological properties of CBP. Compliance of CBP with minimum requirements for pozzolanic characteristics was verified using X-Ray Fluorescence and X-Ray Diffraction. Extensive Image analysis using ImageJ and Origin was employed to verify significant variations of particle size, particle distribution, porosity and surface roughness for different sample mass. Properties of cement paste containing CBP were assessed to capture essential elements on the influence of CBP fineness on density and prismatic compressive strength of cement paste. The overall influence of grinding illustrated that a decline in particle size of CBP was facilitated in samples subjected to prolonged milling times. On the other hand, the reduction of sample mass fed in ball mill corresponded to enhancement of fineness of CBP. Meanwhile, qualitative evaluation of three-dimensional reconstruction of SEM images using ImageJ proved that significant enhancement of fineness led to reduction of surface roughness. Quantification of surface porosity demonstrated that reduced surface porosity originated from finer CBP. Consequently, the research established the feasibility of incorporating finer CBP in cement paste, which significantly contributes to enhancement of prismatic compressive strength. Concerning cement paste density, the inclusion of CBP in cement was not of significant consequence on its density due to similar packing densities of CBP.

Investigation of particle characteristics and enhancing the pozzolanic activity of diatomite by grinding

This study aimed to assess the influence of grinding on improving the pozzolanic activity of a low porosity diatomite. To that end, three diatomites were produced, with 50% passing particle sizes (D50) between 7 and 40 μm, and characterized based on oxide composition, loss on ignition, X-ray diffraction (XRD), particle size distribution, and gas adsorption (specific surface area and porosity). Pozzolanic activity was assessed by electrical conductivity, modified Chapelle test, mechanical testing of lime-based mortar at 7 days, and performance index with Portland cement at 28 days. Additionally, portlandite (CH) consumption by diatomite was monitored up to 91 days of hydration by XRD-Rietveld refinement measurements in CH-diatomite pastes combined with controlled calcination at 900 °C. The grinding procedure ensured effective particle size reduction and produced an ultrafine diatomite (D50 below 10 μm) with low energy consumption. The decline in particle size caused an increase in the specific surface area (SSA) of diatomite without significantly changing pore volume and size. The larger SSA raised the silica solubility and pozzolanic activity of diatomite, altering its classification in terms of pozzolanicity. As evidenced by hydration analysis, the increased reactivity and change in pozzolanicity was due to the rise in CH consumption as the SSA of the diatomite increased.

The multi-scale pore structure of superfine pulverized coal. Part 1. Macropore morphology

The accurate description of the complex multi-scale pore structure plays a crucial role in efficient coal utilization. However, there are few studies about the macroporosity in pulverized coals, which is important for understanding the migration paths and mechanisms. In this work, both macropore geometry and topology of superfine pulverized coal were characterized through mercury intrusion porosimetry (MIP). Furthermore, the permeability of coal with different sizes was addressed based on the percolation theory, and the compressibility was discussed. Finally, the macropore morphology was comprehensively evaluated based on three different fractal models. The results show the pore geometry in superfine pulverized coal can be depicted as the isolated large pore clusters occurring in continuous small pore networks. With the decline in particle size, the compressibility drops by 2.7 × 10−11 Pa−1 and 1.2 × 10−11 Pa−1 for NMG and HN samples. In addition, the fractal analyses confirm that with decreasing particle sizes, the surface fractal dimensions increase for both NMG and HN, whilst the structure fractal dimensions show the opposite. The pore geometry and topology have a combined effect on the permeability, which is correlated to both surface and structure fractal dimension, leading to the maximum permeability around 20 μm for studied coals (954.87 mD for NMG_18.7 and 482.08 mD for HN_23.9). The macropore morphology obtained here is useful for constructing a more comprehensive coal pore network, and better understanding the mass and heat transfer in coal particles, which sheds lights on further exploring the reaction mechanisms of new clean coal utilization technologies.

Hydrogen storage properties of Mg-Li-Al composite system doped with Al2TiO5 catalyst for solid-state hydrogen storage

A systematic investigation was performed on the 4MgH2 + LiAlH4 destabilized system with the inclusion of 5 wt% Al2TiO5 that was prepared by a ball milling process, and the hydrogen sorption performances were studied for the first time. A great advancement of the onset dehydrogenation temperature and de/rehydrogenation kinetics of 4MgH2 + LiAlH4 composite was achieved by doping Al2TiO5 to the composite. For the first and second desorption stages, the 4MgH2 + LiAlH4 + 5 wt% Al2TiO5 composite began to liberate hydrogen at 85 °C and 230 °C. In comparison, the undoped system commenced to liberate hydrogen at 120 °C and 270 °C, which were 35 °C and 10 °C lower, respectively when contrasted with the undoped composite. For the rehydrogenation kinetics, about 1.9 wt% hydrogen was absorbed within 5 min for the 5 wt% Al2TiO5-doped 4MgH2 + LiAlH4 system, whereas the neat sample only absorbed about 1.2 wt% hydrogen under similar conditions. As for the dehydrogenation kinetics, 4MgH2 + LiAlH4 + 5 wt% Al2TiO5 composite desorbed 1.7 wt% hydrogen within 10 min of desorption, while the 4MgH2 + LiAlH4 system released 0.8 wt% hydrogen in the same time frame. The apparent activation energy for the MgH2-relevant decomposition decreased from 121 kJ/mol (4MgH2 + LiAlH4 system) to 102 kJ/mol, after 5 wt% Al2TiO5 was introduced into the destabilized system. The decline in particle size also enhance the hydrogen storage behaviors. The synergistic effect of Al2TiO5 on the hydrogen storage behavior of 4MgH2 + LiAlH4 sample is attributed to the formation of new species of TiH2, AlTi2 and LiTi2O4 after ball milling and heating process, which acted as a real catalyser in the 4MgH2 + LiAlH4 + 5 wt% Al2TiO5 destabilized system.

Investigation of the kinetics of spontaneous combustion of the major coal seam in Dahuangshan mining area of the Southern Junggar coalfield, Xinjiang, China

In the present paper, with using diverse methods (including the SEM, the XRD, the TPO, the FTIR, and the TGA) , the authors analysed samples of the major coal seam in Dahuangshan Mining area with different particle sizes and with different heated temperatures (from 50 to 800 °C at regular intervals of 50 °C). The results from SEM and XRD showed that high temperature and high number of pores, fissures, and hierarchical structures in the coal samples could facilitate oxidation reactions and spontaneous combustion. A higher degree of graphitization and much greater number of aromatic microcrystalline structures facilitated spontaneous combustion. The results from TPO showed that the oxygen consumption rate of the coal samples increased exponentially with increasing temperature. The generation rates of different gases indicated that temperatures of 90 °C or 130 °C could accelerate coal oxidation. With increasing temperature, the coal oxidation rate increased, and the release of gaseous products was accelerated. The FTIR results showed that the amount of hydroxide radicals and oxygen-containing functional groups increased with the decline in particle size, indicating that a smaller particle size may facilitate the oxidation reaction and spontaneous combustion of coal. The absorbance and the functional group areas at different particle sizes were consistent with those of the heated coal samples, which decreased as the temperature rose. The results from TGA showed that the characteristic temperature T3 declined with decreasing particle size. After the sample with 0.15–0.18 mm particle size was heated, its carbon content decreased, and its mineral content increased, inhibiting coal oxidation. This result also shows that the activation energy of the heated samples tended to increase at the stage of high-temperature combustion with increasing heating temperature.

Characterization and comparison of α-lactalbumin pre-and post-emulsion

The main purpose of this research was to comparatively explore the influence of ultrasound (US, 600 W for 30 min) high-pressure homogenization (HPH, 80 MPa for 4 cycle) and combined (US-HPH) treatments on oil-in-water (O/W) emulsion stabilized with α-lactalbumin (α-LA) pre- and post-emulsification. Compared with US pre-treatment, US post-treatment resulted in increase in emulsifying activity (from 103.23 to 113.38 m2/g), emulsifying stability (from 50.79 to 63.74 min) and zeta-potential (from 29.4 to 31.8 mV) of α-LA stabilized emulsion. Particle size and polydispersity index (PDI) of US-HPH α-LA post-emulsion reduced by about 8.94% and 29% than those of US-HPH α-LA pre-emulsion, respectively. US-HPH α-LA post-emulsion had no phase separation for two weeks of storage at ambient temperature upon visual appearance. The observations of the confocal laser scanning microscopy (CLSM) revealed that a remarkable decline in particle size was observed in US-HPH α-LA post-emulsion. Flow behavior of emulsion stabilized with α-LA was detected to be shear-thinning in all treatments. There was no significant alteration in SDS-PAGE in all treatments of pre-and post-emulsification (p > 0.05). The most suitable processing method to produce a fine and stable emulsion was a combined US-HPH post-treatment, having an improving influence on physiochemical and emulsifying properties of emulsion stabilized with α-LA for potential industrial applications.

Vertical and horizontal distribution of regional new particle formation events in Madrid

Abstract. The vertical profile of new particle formation (NPF) events was studied by comparing the aerosol size number distributions measured aloft and at surface level in a suburban environment in Madrid, Spain, using airborne instruments. The horizontal distribution and regional impact of the NPF events was investigated with data from three urban, urban background, and suburban stations in the Madrid metropolitan area. Intensive regional NPF episodes followed by particle growth were simultaneously recorded at three stations in and around Madrid during a field campaign in July 2016. The urban stations presented larger formation rates compared to the suburban station. Condensation and coagulation sinks followed a similar evolution at all stations, with higher values at urban stations. However, the total number concentration of particles larger than 2.5 nm was lower at the urban station and peaked around noon, when black carbon (BC) levels are at a minimum. The vertical soundings demonstrated that ultrafine particles (UFPs) are formed exclusively inside the mixed layer. As convection becomes more effective and the mixed layer grows, UFPs are detected at higher levels. The morning soundings revealed the presence of a residual layer in the upper levels in which aged particles (nucleated and grown on previous days) prevail. The particles in this layer also grow in size, with growth rates significantly smaller than those inside the mixed layer. Under conditions with strong enough convection, the soundings revealed homogeneous number size distributions and growth rates at all altitudes, which follow the same evolution at the other stations considered in this study. This indicates that UFPs are detected quasi-homogenously in an area spanning at least 17 km horizontally. The NPF events extend over the full vertical extension of the mixed layer, which can reach as high as 3000 m in the area, according to previous studies. On some days a marked decline in particle size (shrinkage) was observed in the afternoon, associated with a change in air masses. Additionally, a few nocturnal nucleation-mode bursts were observed at the urban stations, for which further research is needed to elucidate their origin.

Conversion of α-Chitin Substrates with Varying Particle Size and Crystallinity Reveals Substrate Preferences of the Chitinases and Lytic Polysaccharide Monooxygenase of Serratia marcescens

Industrial depolymerization of chitinous biomass generally requires numerous steps and the use of deleterious substances. Enzymatic methods provide an alternative, but fundamental knowledge that could direct potential development of industrial enzyme cocktails is scarce. We have studied the contribution of monocomponent chitinases (ChiA, -B, and -C) and the lytic polysaccharide monooxygenase (LPMO) from Serratia marcescens on depolymerization of α-chitin substrates with varying particle size and crystallinity that were generated using a converge mill. For all chitinases activity was positively correlated to a decline in particle size and crystallinity. Especially ChiC, the only nonprocessive endochitinase from the S. marcescens chitinolytic machinery, benefited from mechanical pretreatment. Combining the chitinases revealed clear synergies for all substrates tested. CBP21, the chitin-active LPMO from S. marcescens, increased solubilization of substrates with high degrees of crystallinity when combined with each of the three chitinases, but this synergy was reduced upon decline in crystallinity.

Magnetic properties of single-domain SrFe12O19 particles synthesized by citrate precursor technique

Nanosize particles of SrFe12O19 have been synthesized by a citrate precursor technique with various Fe/Sr ratios of 12.0 to 9.0. X-ray diffraction (XRD) studies showed the formation of ultrafine, monophasic SrFe12O19 particles with comparable unit cell parameters. Magnetic clusters were observed by scanning electron microscopy and Branauer–Emmett–Teller surface area measurements. Mossbauer results reveal the ferrimagnetic and superparamagnetic nature and the change in hyperfine parameters with decline in particle size and Fe/Sr ratios. The magnetic properties of small SrFe12O19 particles (Fe/Sr=12.0) showed a considerable enhancement in TC from a bulk value of 750–883 K measured for 20–5.7 nm XRD particle size. The shift in Curie temperature is well defined by the finite size scaling formula [TC(D)−TC(∞)]TC(∞)−1=(D/D0)−1/ν with ν=0.75–0.02 and D0=1.52 nm. The change in Hic, σs, and σr values were observed with the decline in particle size and the Fe/Sr ratios where Hic of 6500 Oe is achieved for isotropic SrFe12O19 particles with a Fe/Sr ratio of 10.8. Such changes are explained by the additional Sr leading to the formation of a nonmagnetic layer around the particles which inhibits their growth, limiting them to single-domain size.

The downstream gradation of particle sizes in the Squamish river, British Columbia

AbstractThe exponential downstream decline in particle size predicted by Sternberg (1875) is examined within a highly active alpine fluvial environment, the gravel‐bed Squamish River in southwestern British Columbia. Transect survey procedures for sampling within the coarse alluvial gravels are described in detail. Downstream trends for various particle size statistics, plotted with distance from a major sediment source, are considered according to two scenarios. Evaluation of overall trends indicates that the downstream expression derived by Sternberg (1875) is not the most appropriate; rather, curves are better described by power functions. This reflects a very rapid decline in particle size immediately downstream of the major sediment source. Secondly, evaluation of downstream trends in relation to channel planform determines that exponential functions with different coefficients describe adequately relations within individual planform reaches. There is insufficient evidence to suggest which of these two scenarios may be appropriate. Several lines of evidence suggest that the trends found are more the result of selective sediment transport phenomena than of abrasion, a condition attributed to channel competence within a system dominated by sediment‐supply conditions.