Particle Specific Surface Area Research Articles

Particle Sizing and Surface Area Measurements: A Comparative Assessment of Commercial Air Permeability and Laser Light Diffraction Instruments

Six different commercial powders, finer than 45 μm, were used for examining the effects of particle characteristics on mean particle size and specific surface area. The measurements were carried out using the most commonly used air permeability- and laser light diffraction (scattering) techniques. As the air permeability method has been used as a benchmark for decades in the powder metallurgy (P/M) industry, the physical phenomena that govern the passage of gas through the powder bed under laminar flow conditions were also presented. The experimental data indicate that both methods give similar results for spherical powders. The advantage of laser light systems over gas permeameters is the ability to provide additional information on particle size distribution. Irregularly shaped powders should be analyzed by both techniques, relying on gas permeametry for surface area measurements and on laser light diffraction for the estimation of mean particle size and size distribution. Application of scanning electron microscopy as a complementary technique was found very helpful in the interpretation of data through visualization of individual particles.

Impact of annealing on Cu2O doped with Na/Co: Structural, optical, and electrochemical consequences

Impact of annealing on Cu2O doped with Na/Co: Structural, optical, and electrochemical consequences

Fabrication of Highly Sensitive Electrochemical Sensor Based on Chromium-Doped Ferrite Nanoparticles: Hybrid Graphene Nanosheets for the First Voltammetric Determination of Asenapine Maleate in Formulations and Human Plasma

Ferrite nanoparticles are interesting materials given their unique physical and chemical properties and wide applications. A novel electrochemical sensor based on a series of chromium-nano-ferrites {Fe3+[Fe2+Fe3+ (1-x)Cr3+ x ]O4; x (0.0–1.0} was fabricated for determination of Asenapine maleate (ASE.M). X-ray diffraction revealed the formation of crystallite nano-particles of lattice constant of (8.299–8.345 Å) with a single phase of cubic inverse spinel structures. Particle size and specific surface area were (9.10–27.60 nm) and (60–175 m2g−1) using Transmission electron microscopy and Brunnauer-Emmett-Teller (BET) analysis, respectively. Among this Cr x Fe(3−x)O4 series, (CrFe2O4; x = 1) was appeared to get the smallest particles size and highest BET surface area. The charge transfer resistance (RCT) of (2220, 1680, 765, and 490 Ω) were achieved for Cr x Fe(3−x)O4 NPs/CPE (x = 0.0, 0.4, 0.8, and 1.0), respectively. CrFe2O4 performance was then improved via incorporation of 2D-graphene atomic crystals in a new ferrite-graphene nanocomposite of [0.25%(w/w) CrFe2O4 NPs: 7%(w/w) graphene nanosheets]. The feasibility of this sensor is achieved for determination of ASE.M in brand Saphris® and local Asenapine pharmaceutical products. In addition, a wide linear concentration range of (6.5 × 10−9–1.0 × 10−6 M) with LOD value of 8.88 × 10−10 M were achieved in human plasma.

Production and applications of lead (II) oxide/poly(aniline-co-thiophene) composite materials for enhanced supercapacitor performance

In this work, a novel approach was employed to prepare and utilize lead (II) oxide and poly(aniline-co-thiophene) (PANI-co-PTh) composite materials as electrode materials for supercapacitors, marking the first instance of such utilization in the literature. PANI-co-PTh was synthesized in bulk through chemical polymerization, and the conducting polymers underwent comprehensive spectroscopic, physical, and microscopic characterization. Subsequently, the material, incorporating lead (II) oxide (PbO) as a composite, was employed as electrode materials in asymmetric-type supercapacitors. The main results indicate a clear relationship between the surface area of conducting polymers and their specific capacitance. Notably, PANI-co-PTh-6, possessing the highest surface area, demonstrated the highest specific capacitance. Particle size distribution and specific surface area for PANI-co-PTh-6 were determined as 130 μm and 64.76 m2g−1, respectively. The PbO@PANI-co-PTh-3 configuration exhibited the highest specific capacitance, reaching 294 Fg−1 at a 10 mVs−1 scan rate. Remarkably, during long-cycle experiments, this system demonstrated a capacity retention of 70.69% after 1000 cycles. The inaugural application of the PbO@PANI-co-PTh-3 supercapacitor showcased notable capacitance values, establishing a substantial foundation for future research endeavors in this field.

Effects of cavitation jet combined with ultrasound, alkaline hydrogen peroxide and Bacillus subtilis treatment on the properties of dietary fiber

In this study, we compared the effects of three methods on the structural, physicochemical, and functional properties of insoluble dietary fiber (IDF) in okara: cavitation jet plus ultrasonic treatment (UC), cavitation jet plus alkaline hydrogen peroxide treatment (HC), and cavitation jet plus fermentation with Bacillus subtilis (FC). Compared to UC-IDF, the two types of co-modified IDF showed significant differences in particle size and specific surface area. Structural analyses showed that HC-IDF had a porous structure and complex morphological structure, with a significant increase in the absorption peak area at around 3420 cm−1 and 1051 cm−1, and a significant decrease in thermal stability and crystallinity. Of the three treatments, HC most effectively enhanced the physicochemical and adsorption properties of IDF, including the emulsion stability (84.49% ± 3.5%), water-holding capacity (16.04 ± 0.05 g/g), glucose absorption capacity (53.17 ± 3.44 g/g), cholesterol absorption capacity (32.87 ± 0.89 mg/g), and nitrite absorption capacity (211.7 ± 0.17 μg/g). These results demonstrate the potential of HC-modified okara IDF as a valuable functional food ingredient. Therefore, the cavitation jet combined with alkaline hydrogen peroxide method has a good potential for application in the study of dietary fiber modification.

Influence of the Steel Slag Particle Size on the Mechanical Properties and Microstructure of Concrete

The present paper probes into the influence of the steel slag particle size on the mechanical properties and microstructure of concrete, with steel slag serving as the primary raw material. Steel slag with different particle sizes was selected as the partial substitute material for concrete by mechanical grinding. The influence of steel slag on the compressive strength, bending strength, and microstructure of concrete was determined by laser particle size analyzer, specific surface area analyzer, strength experiment, X-ray diffraction (XRD), and scanning electron microscope (SEM). The results show that mechanical grinding has significant effects on the particle size distribution and specific surface area of the steel slag. The optimal grinding time is 20 min and the specific surface area is 0.65 m2/g. D10, D50 and D90 are 0.91 μm, 16.57 μm and 46.40 μm, respectively. The steel slag with a fine particle size can better fill the pores in concrete and improve the compactness, thus enhancing the mechanical properties of concrete. The change in the steel slag particle size does not change the type of hydration products, but the smaller the particle size of steel slag, the better the gelling activity, the larger the hydration products, the denser the structure, and the better the mechanical properties. Therefore, the present study provides an important theoretical basis and practical guidance for the application of steel slag as an additive in the concrete industry.

Quantitative Analysis of the Physical Properties of Ti6Al4V Powders Used in a Powder Bed Fusion Based on 3D X-ray Computed Tomography Images.

The physical properties of Ti6Al4V powder affect the spreadability of the powder and uniformity of the powder bed, which had a great impact on the performance of built parts made by powder bed fusion technology. Micro-computed tomography is a well-established technique used to analyze the non-destructivity of the objects' interior. Ti6Al4V powders were scanned with micro-CT to show the internal and external information of all the particles. The morphology, particle size distribution, hollow particle ratio, density, inclusion, and specific surface area of the powder samples were quantitatively characterized, and the relationship of flowability with these physical properties was analyzed in this work. The research results of this article showed that micro-CT is an effective way to characterize these items, and can be developed as a standard method of powder physical properties in the future.

Effect of milled pegmatite quarry wastes powders on structure, microstructure and mechanical properties of pegmatite-based geopolymers

In this investigation, mechanical activation (MA) of pegmatite quarry wastes was perform via an eccentric vibratory mill to improve the geopolymeric reactivity. The MA at miscellaneous times (0 to 90 min) resulted in different activation degrees of samples with improved the fineness of particle size and specific surface area from 2.974 to 5.311 m2.g− 1. Geopolymer binders were synthesized by partly replacing the pegmatite quarry waste with 12.5 wt% of metakaolin. The activating solution used was a mixture of 10 M NaOH and Na2SiO3 solution with a volume ratio of 1:1. Reaction kinetics, compressive strength, water absorption, chemical (FT-IR, XRD, 27Al and 29Si MAS NMR), and microstructural (SEM/EDS and TEM) analyses were done to characterize the obtained geopolymer binders. The microstructural characterization reveals that undissolved/unreacted particles decreased while the non-bridge particles increased with pegmatite milled. Under SEM/EDS and TEM, fineness of pegmatite particles is highlighted by the formation of more reaction product. As a result, the compressive strength of geopolymer binders improved from 22.3 to 51.6 MPa for 0 to 60 min of milling. From these results, there is feasibility of valorising feldspathic (pegmatite) quarry wastes as alternative aluminosilicate precursors to develop environmentally-friendly geopolymer binders. The resulting binders with high-strength and low water absorption (≤ 8.6%) associated to minimization of CO2-emissions can be used as potential candidate in structural applications.

Influence of type, dispersion and amount of alumina on the properties of pressed refractories based on fused zirconia stabilized with ~10 % yttrium oxide

The influence of three types of α­alumina, which differ in dispersion — the specific surface area of particles of 1, 3, and 5 m2/g (two of them are active alumina) and their amount (up to 4 %) on the main properties of samples from fused ZrO2 stabilized with ~10 % Y2O3, fired at 1580 °C was studied. The optimum additive, as well as its amount (1 % alumina of lower dispersion), which ensures the production of fired samples with high property indicators, were determined: content of ZrO2 + HfO2 87.80 wt. %, Y2O3 9.20 wt. %, Fe2O3 0.15 wt. %, apparent density 4.71 g/cm3, open porosity 21.0 %, cold crushing strength 31 N/mm2, thermal shock resistance 13 heat cycle (1300 °C — water). No significant advantage of the Al2O3 additive in the form of active alumina has been established, so less dispersed alumina is preferred for economic reasons.
 As a result of the research performed at JSC “URIR named after A. S. Berezhnoy” institution, the technology of products made of fused ZrO2 stabilized with ~10 % Y2O3 was improved, which ensures the production of these products with a higher (although slightly) cold crushing strength and ~3 times higher thermal shock resistance (1300 — water) compared to similar characteristics of currently manufactured products. This can ensure a longer service life of refractories made of fused ZrO2 stabilized with ~10 % Y2O3 and with Al2O3 additive (due to their much higher thermal shock resistance compared to refractories of the same composition but without Al2O3 additive) in various thermal units at consumers’ facilities where this characteristic of refractories is most important.
 Based on the study results, regulatory documentation was developed and full­scale samples of industrial­format products were manufactured.

Using an economic method to prepare TiO2 from natural ilmenite for photodegradable dye removal

In this work, nanoparticles of ilmenite powder (47 nm) were prepared via ball-milling of natural ilmenite ore to enhance the specific surface area of particles. The photocatalytic activity of magnetically separable ilmenite nanoparticles was investigated in the degradation of methyl orange (MO) and methylene blue (MB). The Band gap of the ilmenite nanoparticles was calculated 3.05 eV. The photodegradation results show that ilmenite nanoparticles completely destruct MO and MB in 40 and 50 min under visible irradiation. In order to choose of optimum values of factors, the leaching process was optimized by applying a “Rotatable Central Composite Design” (CCD) technique. For preparing of required precursor, the grind ilmenite was crushed into small particles by ball milling method. In addition, in order to purifying the titanium slag, reduction process was carried out. Effective Factors on sulfuric acid process as follows leaching time, temperature, acid concentration and solid/liquid (S/L) ratio, were studied.

Investigating the impact of x‐ray computed tomography imaging on soluble organic matter in the Murchison meteorite: Implications for Bennu sample analyses

AbstractX‐ray computed tomography (XCT) is a valuable reconnaissance tool for three‐dimensional imaging and identification of distinct lithologies in extraterrestrial samples. It will be used as part of the preliminary examination of samples returned from asteroid (101955) Bennu by the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS‐REx) mission. However, it must first be established whether x‐rays generated during XCT could degrade or alter the organic composition of the returned samples by radiolysis. To test this, we split a crushed sample of the Murchison CM2 meteorite, kept one portion as a control, and irradiated the other portion up to the maximum x‐ray dosage (~180 Gy) that a Bennu sample would experience during an XCT imaging experiment. We then extracted organic compounds from both splits and conducted (i) nontargeted soluble organic analyses to compare the chemical distributions of C‐, H‐, O‐, N‐, and S‐bearing species and (ii) targeted measurements to quantify the abundances of 96 individual soluble organic molecules that included protein amino acids, amines, carboxylic acids, hydroxy acids, carbonyl compounds, polycyclic aromatic hydrocarbons, alcohols, sugars, and N‐heterocycles. We found that XCT imaging of the Murchison meteorite had no measurable impact on the relative abundances or enantiomeric compositions of most of the soluble organic compounds targeted in this study. Elevated total abundances of several soluble organic compound classes were observed in the XCT‐scanned Murchison sample relative to the control. This is likely related to particle size heterogeneity and specific surface area differences between the sample aliquots used for the extractions, rather than a result of the x‐ray exposure. Assuming the samples returned from asteroid Bennu by OSIRIS‐REx have a similar composition to carbonaceous chondrites, these data provide confidence that XCT will not significantly alter their soluble organic compositions.

Mapping of density-dependent material properties of dry manufactured snow using μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu$$\\end{document}CT

Despite the significance of snow in various cryospheric, polar, and construction contexts, more comprehensive studies are required on its mechanical properties. In recent years, the utilization of μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu$$\\end{document}CT has yielded valuable insights into snow analysis. Our objective is to establish a methodology for mapping density-dependent material properties for dry manufactured snow within the density range of 400–600 kg/m3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^3$$\\end{document} utilizing μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu$$\\end{document}CT imaging and step-wise, quasi-static, mechanical loading. We also aim to investigate the variations in the structural parameters of snow during loading. The three-dimensional (3D) structure of snow is captured using μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu$$\\end{document}CT with 801 projections at the beginning of the experiments and at the end of each loading step. The sample is compressed at a temperature of − 18 o\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathrm {^o}$$\\end{document}C using a constant rate of deformation (0.2 mm/min) in multiple steps. The relative density of the snow is determined at each load step using binary image segmentation. It varies from 0.44 in the beginning to nearly 0.65 at the end of the loading, which corresponds to a density range of 400–600 kg/m3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^3$$\\end{document}. The estimated modulus and viscosity terms, obtained from the Burger’s model, show an increasing trend with density. The values of the Maxwell and Kelvin–Voigt moduli were found to range from 60 to 320 MPa and from 6 to 40 MPa, respectively. Meanwhile, the viscosity values for the Maxwell and Kelvin–Voigt models varied from 0.4 to 3.5 GPa-s, and 0.3–3.2 GPa-s, respectively, within the considered density range. In addition, Digital Volume Correlation (DVC) was used to calculate the full-field strain distribution in the specimen at each load step. The image analysis results show that, the particle size and specific surface area (SSA) do not change significantly within the studied range of loading and densities, while the sphericity of the particles is increased. The grain diameter ranges from approximately 100 μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu$$\\end{document}m to nearly 400 μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu$$\\end{document}m, with a mode of nearly 200 μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu$$\\end{document}m. The methodology presented in this study opens up a path for an extensive statistical analysis of the material properties by experimenting more snow samples.

Effects of explosion puffing on the native structural organization and oil adsorption properties of starch

The effects of explosion puffing (EP) on the native structural organization (i.e., thermal properties, crystalline structure, short-range order, granule morphology and powder properties) and oil adsorption properties of puffed starch (PS) were investigated. The results showed that EP treatment could decrease the melting enthalpy of starch double helices and increase the V-type crystallinity. The highest V-type crystallinity (24.7 %) was obtained when the puffing pressure was 0.4 MPa and the starch:ethanol:water ratio was 1:2:1 (w/w). By controlling the puffing conditions, EP treatment can alter the morphology, and increase the particle size, flowability and specific surface area of PS. The high amorphous proportion and porous sheet structure of PS resulted in the highest oil adsorption capacity when the starch:ethanol:water ratio was 1:1:1 (w/w). Pearson correlation analysis showed that oil adsorption capacity was significantly and positively correlated with the 1022/995 cm−1 value and V-type crystallinity, but negatively correlated with bulk density and angle of repose. Furthermore, oil retention capacity was strongly dependent on V-type crystallinity. These findings demonstrated that EP is an innovative technology with the potential to enhance the V-type crystallinity and adsorption performance of starch.

Influence mechanism of dispersion and agglomeration characteristics of micron/nano carbon dust on its combustion kinetics and explosion process

Due to the widespread use of lithium-ion batteries, evaluations of the flammability and explosive characteristics of carbon dust materials as anodes require attention. Carbon dust often reaches the micron/nano scale, and dust particle state and explosion risk generated in different industrial scenarios are different, which is in urgent need of research. Nanoscale dust has relatively static coagulation properties and shows characteristics of dispersion and reagglomeration under a certain airflow. The particle size characteristics affect its thermodynamic characteristics and various consequence parameters of dust explosion. The oxidation and combustion characteristics are mainly affected by dust particle size distribution characteristics. The apparent activation energy is mainly affected by the proportion of small and medium-sized particles and pre-exponential index factor is mainly affected by the dust overall average particle size and specific surface area. The explosion consequence parameters are affected by the thermodynamic parameters, by the disturbance state, particle distribution degree of dust cloud and other factors, which affect the heat radiation and heat transfer process to some extent resulting in different explosion consequence parameters. Due to the agglomeration characteristics of nano-level dust, the minimum ignition energy and minimum ignition temperature of nano-level dust are generally smaller than that of micron level dust.

Kinetic studies of ignition of coal char particle suspension in hot air

Coal ignition has been a focal point in the pursuit of improved energy efficiency and reduced emissions. This study focuses on investigating the kinetic characteristics of char ignition within a closed reactor. The combustion process is modeled using a one-step global reaction in a quiescent air environment. The results show that particle ignition time increases with equivalence ratio and particle size, while decreases with gas initial pressure and initial temperature. Particle ignition temperature is minimally affected by the particle size, slightly influenced by the gas initial pressure and initial temperature, but substantially influenced by the equivalence ratio. In the fuel-rich condition, the coal char combustion exhibits a thermal runaway stage, primarily driven by the escalating particle temperature, followed by a decaying stage, mainly influenced by the depleting oxygen mass fraction. The dominant kinetic factors affecting the heat release rate (HRR) peak are detailly investigated: the HRR peak shows an initial increase and subsequent decrease with the equivalence ratio, which is mainly controlled by the total particle number and particle temperature; Particle size affects the HRR peak through altering the total particle specific surface area, i.e., the product of the particle number and the particle diameter squared; the gas initial pressure and temperature all affect the HRR peak through directly altering the gas density. Additionally, larger retention coefficient leads to faster particle ignition and higher HRR peak. These findings provide valuable insights into the regulations of coal combustion processes, particularly in scenarios involving elevated pressure and temperature, such as coal/mine explosions.

In situ synthesis and regulation of spherical Ti6Al4V powder by calciothermic self-propagating metallurgy

In this paper, spherical Ti6Al4V alloy powder was successfully prepared by calciothermic self-propagating rapid reaction method, in which TiO2, V2O5, Al and Ca were used as raw materials. The reduction reaction can be completed in minutes with no need for any external energy and additives in the reaction process. By investigating the influence of the additives, the amount of reductant Ca added, the reaction pressure and the particle size of Ca, on the composition as well as the morphology of the product, the optimal alloy powder with an low oxygen content of 0.21 wt% was obtained, whose average particle size and specific surface area were 15.28 μm and 0.284 m2/g respectively. Moreover, this research implied the adiabatic temperature of the system and the liquid Ca are the main factors that pose influence to the powder morphology during sintering-reduction-spheroidization-solidification process. Compared with the traditional Ti6Al4V alloy powder preparation process, this process stands out with characteristics of high purity, short production cycle and environmental friendliness, which show high commercialization potential for industrial preparation of Ti6Al4V and similar alloy powders.

A study on the preparation of V2O5 from NH4V3O8 based on thermal decomposition including the thermal decomposition temperature effect, mechanism and kinetics

This study extensively investigated the thermal decomposition process of NH4V3O8, examining how varying temperatures affect the physicochemical properties of the products, as well as exploring the mechanism and kinetics of the process. Through XRD and SEM analysis, the study identified the phase compositions, crystal structures, and micromorphology of the thermal decomposition products. It also systematically investigated the effects of temperature on particle size and specific surface area, identified the lowest thermal decomposition temperature, and proposed the reaction equations. Additionally, by employing FT-IR analysis and DFT calculation, the study revealed the molecular-level thermal decomposition mechanism of NH4V3O8. Finally, the study calculated the kinetic parameters of NH4V3O8 thermal decomposition using the Kissinger and Kissinger-Crane methods and established the rate equation. These findings not only provide practical guidance but also serve as theoretical references for the thermal decomposition of other metal ammonium salts.

Evaluating methodological parameters to quantify particle size of organic soil material with laser diffraction

AbstractThe recognition that texture is a “master soil property” points toward the need for actual quantification of particle size in organic soil material. Using a multi‐wave particle size analyzer, fibric and sapric soil samples were circulated in deionized water through a closed aqueous loop at 9.6 L min−1, and the following methodological parameters were investigated: pre‐treatment, circulation time, and refractive index. Our results show that pre‐treatment for organic soil samples is dependent upon the degree of decomposition; the intact and dispersed PSDs for fibrous samples were similiar, whereas the PSDs for sapric samples showed a shift from 500–2000 (intact) μm to 5–100 (dispersed) μm. Circulation time was investigated using mean particle diameter and specific surface area. We demonstrated that as circulation time increased, the mean particle diameter decreased and the specific surface area increased out to 30 min as mechanical dispersion and/or fragmentation of organic particles occurred. However, circulation time after 5 min is not significantly different in terms of mean particle diameter. To investigate refractive index, 12 optical models were created. When determined across all intact samples, uncertainty was low within individual bins, with a maximum value of 0.07 ± 0.04% v/v. For dispersed samples, uncertainty increased within the silt sized region and had a maximum value of 0.17 ± 0.07% v/v. This study demonstrates that the particle diameter of organic soil material can be measured by LD with comparable certainty as that of mineral soil material using the methodological approach used in this study.

Sol-Gel-Controlled Size and Morphology of Mesoporous Silica Microspheres Using Hard Templates.

Mesoporous silica microspheres (MPSMs) represent a promising material as a stationary phase for HPLC separations. The use of hard templates provides a preparation strategy for producing such monodisperse silica microspheres. Here, 15 MPSMs were systematically synthesized by varying the sol-gel reaction parameters of water-to-precursor ratio and ammonia concentration in the presence of a porous p(GMA-co-EDMA) polymeric hard template. Changing the sol-gel process factors resulted in a wide range of MPSMs with varying particle sizes from smaller than one to several micrometers. The application of response surface methodology allowed to derive quantitative predictive models based on the process factor effects on particle size, pore size, pore volume, and specific surface area of the MPSMs. A narrow size distribution of the silica particles was maintained over the entire experimental space. Two larger-scale batches of MPSMs were prepared, and the particles were functionalized with trimethoxy(octadecyl) silane for the application as stationary phase in reversed-phases liquid chromatography. The separation of proteins and amino acids was successfully accomplished, and the effect of the pore properties of the silica particles on separation was demonstrated.

Effect of aggregate size on water distribution and pore fractal characteristics during hydration of cement mortar based on low-field NMR technology

The influence of aggregate size (AS) on the hydration of cement mortar is very important for improving the quality and stability of cement mortar. This study aims to study the effect of AS on water distribution and pore structure characteristics on the early-age hydration of cement mortar by low-field NMR technology. The hydration degree and fractal dimension of the hydration process were calculated by the T2 spectrum. The water distribution models at different times and locations during the hydration process were established based on the MRI bitmap data. The variation law of water volume at different locations was studied. The results indicate that: In the process of hydration, some of the water is consumed by the hydration reaction, and some of the water oozes out. The water in the large pores flows to the small pores under the action of hydrostatic pressure. AS affected the uniformity of the cement mortar at the initial state, and the gradation of the sand could improve the uniformity. The smaller AS was, the more complex the pore water distribution and changed during hydration. The bleeding mass was directly proportional to the porosity and inversely proportional to the specific surface area of particles. The effect of porosity on bleeding mass was more significant than AS. Pore fractal dimension was negatively correlated with aggregate diameter. In the initial stage, when the aggregate composition became complex, the change of fractal dimension with time also became complex. The fractal dimension increased gradually with the increase of hydration time. The gel pores (G) did not have fractal characteristics from beginning to end, capillary pores (C) and transition pores (T) had fractal characteristics after a particular time of hydration reaction. Although the air-voids (A) had fractal characteristics from beginning to end, they were not continuous.