Laser Scattering Particle Size Analyzer Research Articles

Dehydrogenation and spheroidization of titanium hydride powder based on fluidization principle

ABSTRACT Dehydrogenation of TiH2 powder is an important method for preparing low-cost titanium powder. In this study, a novel dehydrogenation process of titanium hydride powder was developed based on the fluidization principle. TiH2 powder with particle sizes of <75 μm was placed evenly on the fluidization bed in a specially designed reactor and dehydrogenated at 560°C for 120 min with argon gas flowing from the bottom to top of the reactor. The resulting powder was analyzed using X-ray diffractometry, scanning electron microscopy, Hall flowmeter and laser scattering particle size analyzer. It was evident that a Ti powder with a small amount of TiH1.5 was obtained after the dehydrogenation process at a relatively low temperature. The edges and corners of the particles became rounded due to the thermodynamic driving force originated from the reduction of particle surface areas. The fluidity of powder was also improved due to the increase of sphericity of the powder particles during dehydrogenation. After dehydrogenation, the particle size range became smaller, and the average particle size increased, showing that slight sintering of the very fine titanium particles occurs.

Defects in parts manufactured by selective laser melting caused by δ-ferrite in reused 316L steel powder feedstock

The presence of δ-ferrite in 316L stainless steel powder reused several times contributes to structural defect formation in selective laser melted parts built using the pin support structure. The virgin 316L stainless steel powder is fully austenitic. After several powder reuse cycles, reused powder has a finer particle size and about 6 vol. % of δ-ferrite. Phase change occurs due to the thermal cycles imposed on the particles near the melt pool, via spattering and further interaction of in-flight droplets with the laser beam. Phase transformation changes the magnetic behavior of the powder leading to particle clustering in the powder bed. The uniformity of the powder bed is affected causing defects such as porosity, delamination, warping and lack of fusion. These defects are more prone to occur at the beginning of the building process. The magnetic and non-magnetic fractions of the reused powder were separated from each other using magnetic separation. Powder characterization was performed using scanning electron microscopy, laser scattering particle size analysis, X-ray diffraction, and magnetization measurements. An explanation for the formation of such defects based on the magnetic behavior of δ-ferrite powder particles is proposed. The results suggest that magnetic separation should be used to remove magnetic particles after several reuse cycles.

Effect of thermal regeneration of diatomite adsorbent on its efficacy for removal of dye from water

Reduction in adsorption capacities of adsorbents is limiting of its wider application for water treatment. In this study, we developed a new approach for recycling diatomite to be used adsorbent. The laser scattering particle size analyzer, X-ray diffraction, scanning electron microscopy/energy-dispersive X-ray and Brunauer–Emmett–Teller analysis were used to evaluate the structural characteristics of treated samples. The adsorption efficacy of raw and heated diatomite at 300, 600 and 900 °C for textile dyestuff removal from wastewater was investigated. The characterization results show insignificant changes except some deconstructions were occurred after treatment at 900 °C. The maximum adsorption capacities were obtained at pH 2 and adsorbent dosage of 4 g L−1. The required time to reach the equilibrium was 30 min, and diatomite treated at 600 °C is acted as an excellent adsorbent. The kinetic studies were better described by the pseudo-second-order kinetic model. The isotherms experimental data showed that the adsorption of dye onto raw diatomite, DH300 and DH600 follows the Brunauer–Emmett–Teller isotherm model, but its adsorption onto DH900 conforms well to Freundlich isotherm model. Recycling of diatomite using thermal treatment was useful. At 600 °C which is considered the best regeneration temperature, the adsorbed dye was completely despaired, and around 73% was restored after three regeneration cycles.

Particle size measurements and scanning electron microscopy (SEM) of cocoa particles refined/conched by conical and cylindrical roller stone melangers

The particle size distribution (PSD) and the microstructure of the non-fat particles in chocolates are very important to the appearance, mouth feel and texture of the chocolate products. Refining/conching is critical to chocolate processing because most particle size reduction is made and the microstructure of the particles is developed in this process. Currently, the most commonly used comprehensive measurement method for chocolate products is using a laser scattering particle size analyzer, which is relatively expensive and inaccessible to small manufacturers. In this study, three potential alternative methods (micrometer, light microscopy image analysis and Hegman gauge) for the laser scattering method were used to measure the size of cocoa particles at different stages of refining/conching. Also, the influences of the sample weights of cocoa and melanger configuration (conical roller and cylindrical roller) on the efficiency of refining/conching were studied. The performances of the two melangers were similar, however, cylindrical roller stones tend to generate thin and flat particles during the first 4 h of refining. Varying sample weights only influenced particle size reduction at early stages of refining. From the SEM images, a decreasing trend in the number of large spherical particles and an increasing trend in the number of small flat irregularly shaped particles were observed. The particle size measurements by the micrometer of cocoa particles refined for 0.5 h was greater than all other methods. However, the particle size measurements by the micrometer of particles refined for 2 h, 4 h, and 24 h were smaller than the measurements made by any other methods. On the other hand, except for cocoa being refined for 0.5 h, the particle size measurements tested by light microscopy image analysis for all cocoa samples were much greater than other measurement methods. Both the micrometer and light microscopy image analysis can be used to monitor the PSD of cocoa particles during refining/conching. However, the Hegman gauge failed to provide meaningful measurements.

The composition and technology of the 3–4th century CE decorative earthen plaster of Pithalkhora caves, India

This research focuses on the characterization of ancient decorative earthen plaster of India's Pithalkhora group of caves. The restoration strategies being planned for the earthen plaster demand detailed scientific investigation to understand technology and composition so as to prepare matching plaster. The mineralogical, micro-structural and chemical characterization of the earthen plasters have been investigated by analytical tools like petrological microscope, XRF, CHN analysis, laser scattering particle size analyzer, FTIR, XRD, Scanning Electron Microscopy, thermal analyzer (DGA/DTA) as well as on-site observations. A comparative study with nearby sites portrays the earthen plaster of Pithalkhora coarser (silt: 62–100%, sand: 2–2.2%) with traces of clay (0–2%); hence it may be prone to damage by grain breakages. The chemical composition confirms that the aggregates mixed with the earthen plaster belong to that of locally available basaltic origin. SEM studies show addition of quartz and traces of clay (illite and montmorillonite) to augment the flexibility and performance of the plaster. The restoration plaster should be synthesized with aggregates of locally available basaltic rock mixed with slaked lime in addition with rice husk and other vegetal fibres as vegetal additive to overcome the shrinkage of the plaster.

Flocculation and dispersion studies of iron ore using laser scattering particle size analysis

In many mineral processing applications it is necessary to know the isoelectric points of the various minerals in the ore to properly perform flotation and other mineral separations. However, current zeta potential analysis technology used to determine the isoelectric point of a particle suspension cannot deliver the isoelectric point of each individual mineral, just an average of the mineral system. Traditionally, individual isoelectric points have been gathered by testing pure, synthetic minerals. These values can vary widely depending on the mineral synthesis procedure and the water quality used during the isoelectric point analysis. A more robust approach for determining the actual isoelectric point of a particular mineral in a mixture of minerals is needed. This paper details a method for determining the isoelectric point of an iron oxide mineral in a siliceous iron ore. The method uses a laser scattering particle size analyzer and a pH electrode to determine the pH at which the liberated mineral particles begin to flocculate as pH is decreased. The pH at which the average particle size rises dramatically is the isoelectric point of the mineral with the highest isoelectric point in the ore. This measurement technique was used on natural hematite, goethite and siderite ores as well as a synthetic mixture of pure silica and pure hematite. The results for synthetic hematite mixtures were comparable to literature values.

Study on the preparation of the CdS x Se1−x @ZrSiO4 red ceramic pigments and its properties

The color of the CdSxSe1-x@ZrSiO4 red ce- ramic pigment is associated with the condensed CdSx Se1-x particles, which is incorporated into zirconium silicate microcrystals as a robust inclusion body. The pigments were prepared via the gel co-precipitation method. The as-prepared pigments were characterized by X-ray diffraction, CIE-L*a*b* color measurement, scanning electron microscopy, acoustic particle sizer, dynamic laser scattering particle size analysis and polarized optical microscopy, respectively. The results indicate that the pigments prepared in ethanolamine solution show a more intensive tinting capacity, superior thermal stability and the finer particle size than those prepared in prevailing pure water. The prepared red pigments can be potential applied as a promising ink material for inkjet printing. Graphical Abstract Diagram of acid picking pores on pigment encapsulation

Predicting One-Day, Three-Day, and Seven-Day Heat of Hydration of Portland Cement

AbstractThis paper aims to develop empirical equations predicting one-day, three-day, and seven-day heat of hydration of portland cement at 23°C and water to cement ratio of 0.5. Isothermal conduction calorimetry was implemented to measure the heat of hydration of portland cements for up to seven days. X-ray diffraction was used to study the mineralogy and also for quantification of phase composition of portland cements. Particle size distribution of cements was measured using a laser scattering particle size analyzer. Blaine fineness of cements was measured using a Blaine permeability apparatus in accordance with the standard test methods for the fineness of hydraulic cement by air-permeability apparatus procedure. The results indicate that the one-day, three-day, and seven-day heat of hydration of a specific portland cement ground to different finenesses is changing linearly with the cement mean particle size. This research shows that the mean particle size is a suitable measure of cement fineness to co...

Synthesis of strongly fluorescent molybdenum disulfide nanosheets for cell-targeted labeling.

MoS2 nanosheets with polydispersity of the lateral dimensions from natural mineral molybdenite have been prepared in the emulsions microenvironment built by the water/surfactant/CO2 system. The size, thickness, and atomic structure are characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), and laser-scattering particle size analysis. Meanwhile, by the analysis of photoluminescence spectroscopy and microscope, the MoS2 nanosheets with smaller lateral dimensions exhibit extraordinary photoluminescence properties different from those with relatively larger lateral dimensions. The discovery of the excitation dependent photoluminescence for MoS2 nanosheets makes them potentially of interests for the applications in optoelectronics and biology. Moreover, we demonstrate that the fabricated MoS2 nanosheets can be a nontoxic fluorescent label for cell-targeted labeling application.

Combination of doxorubicin-based chemotherapy and polyethylenimine/p53 gene therapy for the treatment of lung cancer using porous PLGA microparticles

In this study, porous PLGA microparticles for the co-delivery of doxorubicin and PEI25K/p53 were successfully prepared by the water–oil–water emulsion solvent evaporation method, using ammonium bicarbonate as a porogen. The porous microparticles were obtained with a mean diameter of 22.9±11.8μm as determined by laser scattering particle size analysis. The particles’ surface porous morphology and distributions of doxorubicin and p53 were systematically characterized by scanning electron microscopy, flow cytometry, fluorescence microscopy and confocal laser scanning microscopy, revealing that doxorubicin and the plasmid were successfully co-encapsulated. Encapsulation efficiencies of 88.2±1.7% and 36.5±7.5% were achieved for doxorubicin and the plasmid, respectively, demonstrating that the porous structure did not adversely affect payload encapsulation. Microparticles harboring both doxorubicin and PEI25K/p53 exhibited enhanced tumor growth inhibition and apoptosis induction compared to those loaded with either agent alone in A549 human lung adenocarcinoma cells. Overall, the porous PLGA microparticles provide a promising anticancer delivery system for combined chemotherapy and gene therapy, and have great potential as a tool for sustained local drug delivery by inhalation.

Monodispersed composite particles prepared via emulsifier‐free emulsion polymerization using waterborne polyurethane as microreactors

ABSTRACTMonodispersed polystyrene particles in submicrometer size were intriguingly prepared through emulsifier‐free batch‐seeded emulsion polymerization using nonmonodispersed waterborne polyurethane (WBPU) beads as microreactors. Different feed ratios of styrene (St)/WBPU for the preparation of composite particles were investigated, and the size–growth course was experimentally followed. The morphology and dispersity of the particles were characterized by scanning electron microscopy together with dynamic laser scattering particle size analyzer. Their inside structure was further characterized by transmission electron microscopy with ultramicrotomy combined with X‐ray photoelectron spectroscopy for the composite particles' surface analysis. The probable grafting polymerization of St from WBPU was verified by Fourier transform infrared spectroscopy and nuclear magnetic resonance instrument. The obtained composite particles were again employed as the seeds in the emulsion copolymerization of methyl methacrylate. As a result, the formed multilayered composite particles with reverse core–shell structure were also monodispersed and spherical. The mechanism of the formation of the monodispersed particles was proposed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40985.

Investigation of Physical Properties of Graphene-Cement Composite for Structural Applications

The hydration of cement generates heat due to the exothermic nature of the hydration process. Poor heat dissipation in mass concrete results in a temperature gradient between the inner core and the outer surface of the element. High temperature gradients generate tensile stresses that may exceed the tensile strength of concrete thus leading to thermal cracking. The present paper is an attempt to understand the thermal (heat sink property) and microstructural changes in the hydrated graphene-Portland cement composites. Thermal diffusivity and electrical conductivity of the hydrated graphene-cement composite were measured at various graphene to cement ratios. The mass-volume method was implemented to measure the density of the hydrated graphene-cement composite. Particle size distribution of Portland cement was measured by using a laser scattering particle size analyzer. Heat of hydration of Portland cement was assessed by using a TAMAIR isothermal conduction calorimeter. Scanning electron microscopy (SEM) was implemented to study microstructural changes of the hydrated graphene-cement composites. The mineralogy of graphene-cement and the hydrated graphene-cement composites was investigated by using X-ray diffraction. The findings indicate that incorporation of graphene enhances the thermal properties of the hydrated cement indicating a potential for reduction in early age thermal cracking and durability improvement of the concrete structures.

Combustion Synthesis of the MgAl&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; Using Glycerin from the Production of Biodiesel

This work aims to investigate the glycerin from the biodiesel as fuel in the combustion synthesis into two routes, one for high temperature called direct route, in order to inhibit the formation of acrolein and compare it with the conventional combustion synthesis at low temperatures, using as fuels saccharose, pure glycerin, pure glycerin gel, glycerin from biodiesel, biodiesel from glycerin dried 24 h, biodiesel from glycerin gel dried 24 h to obtain the magnesium aluminate spinel (MgAl2O4). The synthesis was performed from the mixture of the precursors (Al (NO3)3.9H2O and Mg (NO3)2.6H2O) in water with the addition of the fuels. In the direct route case, the mixture was placed in a furnace heated to 500°C followed by calcination at different temperatures for 2 h. In the conventional route cases, the mixtures were slowly heated to 800°C for 2 h. The obtained powders, product of the combustion reactions, were characterized by X-ray diffraction (XRD), laser scattering particle size analyzer and scanning electron microscopy (SEM). The results showed that the product (powder) obtained by direct reaction was the MgAl2O4 as the only crystalline phase formed with particle sizes of approximately 41 μm. Even so, small particles with sizes of about 30 nm were also observed according to measurements on SEM images.

Synthesis of stoichiometric Y2Si2O7 powders by sonohydrolysis-assisted sol–gel route

Stoichiometric compounds Y2Si2O7 were synthesised by an intensified sonohydrolysis–condensation reaction using hydrate yttrium nitrate and tetraethyl orthosilicate as starting materials. The resulting powders were characterized by means of thermo gravimetric–differential thermal analysis, high temperature X-ray diffraction, electron probe microanalysis, scanning electron microscopy, laser scattering particle size analyzer, N2 adsorption–desorption isotherms measurements and specific surface area analysis. We found that the phase formation and texture were very dependent on the sol–gel process parameters such as starting compounds, catalyst, water content, molar ratios of Y3+/Si4+ and other experiment conditions. The combined effects of polyethylene glycol and acetic acid on the prepared powders have been discussed. The investigation on thermal stability of the obtained disilicate is also presented for potential high temperature membrane or thermal barrier/environmental barrier coating application.

Strongly luminescent monolayered MoS2 prepared by effective ultrasound exfoliation

Intense ultrasound in a pressurized batch reactor was used for preparation of monolayered MoS2 nanosheets from natural mineral molybdenite. Exfoliation of bulk MoS2 using ultrasound is an attractive route to large-scale preparation of monolayered crystals. To evaluate the quality of delamination, methods like X-ray diffraction, Raman spectroscopy and microscopic techniques (TEM and AFM) were employed. From single- or few-layered products obtained from intense sonication, MoS2 quantum dots (MoSQDs) were prepared by a one-pot reaction by refluxing exfoliated nanosheets of MoS2 in ethylene glycol under atmospheric pressure. The synthesised MoSQDs were characterised by photoluminescence spectroscopy and laser-scattering particle size analysis. Our easy preparation leads to very strongly green luminescing quantum dots.

Techniques for measuring particle size distribution of particulate matter emitted from animal feeding operations

While various techniques for measuring particle size distributions (PSD) of particulate matter (PM) exist, there is no a single agreed upon standard or reference method for PM with different characteristics. This study investigated differences in the PSD measurements by four PSD analyzers: LS13 320 multi-wave length laser diffraction particle size analyzer, LS230 laser diffraction particle size analyzer, LA-300 laser scattering particle size analyzer, and Coulter Counter Multisizer3 (CCM3). Simultaneously collected total suspended particulate (TSP) samples in a commercial egg production house were analyzed by the four analyzers for PSDs. In addition, four types of testing powders (limestone, starch, No.3 micro aluminum, and No.5 micro aluminum) were also analyzed by these four PSD analyzers. The results suggest when comparing measured mass median diameters (MMDs) and geometric standard deviations (GSD) of the PSDs, the laser diffraction method (LS13 320, LS230 and LA-300) provided larger MMDs and broader distributions (GSDs) than the electrical sensing zone method (CCM3) for all samples. When comparing mass fractions of PM10 and PM2.5 between the measured values and the lognormal fitting values derived from the measured MMDs and GSDs, lognormal fitting method produced reasonably accurate PM10 mass fraction estimations (within 5%), but it failed to produce accurate PM2.5 mass fraction estimations. The measured PM2.5 mass fractions significantly differed from the lognormal fitting PM2.5 fractions and the mean differences reached as high as 95%. It is strongly recommended that when reporting a PSD of certain PM samples, in addition to MMD and GSD, the mass fractions of PM10 and PM2.5 should also be reported.

Studies and Researches on the Obtaining of Sintered Gradual Porous Structures by Irregular Nickel Powders Sedimentation

The aim of this work is to obtain sintered porous membranes with graded structure for microfiltration by sedimentation and sintering of metallic powders. Our previous studies have demonstrated the possibility of obtaining sintered porous materials with graded structure by sedimentation. In this paper, irregular nickel particles were used having a grain size in the 2-90 µm range evaluated using scanning electron microscopy and laser scattering particle size analyzer. The powders were sedimented into a sintering die in a sedimentation medium consisting of water and dispersant agent. After drying, the samples were sintered at 1000°C for 10 minutes in vacuum (~1•10-3 Pa). The structures obtained were characterized by scanning electron microscopy and mercury porosimetry. The pore size distribution was between 5-72 µm. The flow rate - pressure drop curves were experimentally determined and the viscous permeability coefficient was calculated using Darcy’s law (Ψv=0.14•10-12 m2). The absolute filtration fineness measured was 20 µm and the relative filtration fineness (95%) obtained for our membranes was 11 µm respectively. The possible applications for the studied membrane are: water microfiltration, environmental technologies, filtering lubricants and cleaning agents

Characterization of Gradual Porous Ceramic Structures Obtained by Powder Sedimentation

Asymmetric membranes present better separation and service characteristics than the symmetric ones. In our preliminary studies the possibility of obtaining sintered porous materials with gradual structure by sedimentation of metallic and ceramic powders was demonstrated. Zirconium silicate (ZrSiC 4 ) particles were used for the manufacturing of the porous supports, and mullite powder was deposited by sedimentation in order to achieve the active layer with pores size gradient. The used powders and the obtained structures were characterized by laser scattering particle size analyzer, scanning electron microscopy and mercury porosimetry. The permeability and the filtration fineness of the structures were also determined. By using a thin active layer made of small particles deposited onto a macro-porous support, one can achieve membranes with high flow rates and filtration fineness in the microfiltration area.

Study of gradual porous metallic membranes obtained by powder sedimentation

In our preliminary studies the possibility of obtaining sintered porous materials with gradual structure by sedimentation of metallic powder was demonstrated. In this paper we continued our studies on the influencing factors of the sedimentation of metallic powders. Irregular and spherical nickel particles were used having a grain size in the 2–90 μm range measured by the laser scattering particle size analyzer. The particles with irregular shape and larger diameter can sediment faster than the spherical and the smaller diameter particles. The sedimentation rate is also influenced by the sedimentation medium and the quantity of the dispersant agent. Deviations from Stokes law was observed in the case of the irregular particles. The gradual structure is influenced by the sintering regime and the powders characteristics too. The obtained structures were characterized by scanning electron microscopy and mercury porosimetry. The permeability and the filtration fineness were also determined.

Effect of Critical Micelle Concentration of Sodium Dodecyl Sulfate Dissolved in Calcium and Carbonate Source Solutions on Characteristics of Calcium Carbonate Crystals

Various concentrations of anionic surfactant, sodium dodecyl sulfate (SDS), were used to control the growth of calcium carbonate crystals. The obtained calcium carbonate particles were characterized by Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), laser scattering particle size analyzer and zeta potential analyzer techniques. The effect of various concentrations including critical micelle concentration (CMC) in calcium and carbonate source solutions on the polymorph, morphology, particle size distribution and zeta potential of the particles were studied. It was demonstrated that varied SDS concentrations in carbonate source solution has obvious effect on the characteristics of calcium carbonate particles, while varied SDS concentration in calcium source solution does not affect the characteristics. Also, it was observed that SDS affected orientation development of calcium carbonate crystals.