Effect Of Initial Particle Size Research Articles

Attrition and morphological analysis of CaCO3 corresponding to oxy-fuel circulating fluidized bed conditions

The specific surface area of CaCO3 has always been an essential parameter for various oxy-fuel combustion processes and chemical looping processes. However, the circulating of bed material through the furnace, cyclone and loop-seal in an oxy-fuel circulating fluidized bed (CFB) reactor may trigger the particle size changes as a result of rapid collisions among particles and friction with the inner refractory wall. Rather than considering only the effect of initial particle size, it is significantly important to emphasize on the change in limestone particle size due to in-reactor attrition. In addition, the changes are further enhanced with calcination reaction that occurred under high-temperature conditions. Herein an investigative account of limestone in a lab-scale CFB process was presented by using two types of fluidizing media (Air, CO2) to determine its attrition and morphological changes under simulated operating conditions for riser and loop-seal. A significant difference in attrition index was observed as calcination of limestone occurred at high temperature under air atmosphere which was not observed under CO2 condition. With similar cross-sectional area observed for both the tested (CO2 condition) and re-carbonated limestone, it was concluded that re-carbonation of calcined lime at high CO2 concentration in the loop-seal resulted in a comparable abrasion resistance that further improved desulfurization performance by reducing the amount of ultra-fine particles generated from limestone.

Effect of initial particle size and surface charge on the formation of the plasma protein corona on chitosan‐based nanoparticles

AbstractWhen a nanoparticle interacts with the biological environment, its surface is covered by a layer of biomolecules such as proteins and lipids called a protein corona. Given the importance and impact of the protein corona on the fate of nanoparticles in the body, it is important to study the interaction of nanoparticles with proteins. This study investigated the impact of the initial size and surface charge of nanoparticles on the changes in protein corona thickness on chitosan‐based nanoparticles after exposure to blood plasma. To be able to separate the chitosan‐based nanoparticles from the blood plasma, magnetic nanoparticles were coated with chitosan (with a positive charge) and carboxymethyl chitosan (CMC; with a negative charge) in two different size ranges of 200–250 and 300–350 nm. The coated nanoparticles' chemical composition, properties, and morphology were investigated using Fourier‐transform infrared spectroscopy, X‐ray diffraction, dynamic light scattering (DLS), zeta potential measurements, transmission electron microscopy, and field emission scanning electron microscope. The results confirmed the formation of nanoparticles based on chitosan and CMC. Subsequently, these nanoparticles were exposed to blood plasma to examine the protein corona that formed. The DLS and zeta potential measurements showed that the surface charge and particle size of the nanoparticles significantly influenced the formation of the protein corona. The results revealed that the smaller particle size and the positive surface charge of the nanoparticles resulted in the formation of a thicker corona. In addition, it showed that after exposure to the blood plasma proteins, the positive charge of the particles changed to a negative charge.

Effects of initial particle sizes of Triarrhena lutarioriparia on processing performance, material properties, and heavy metal speciation in sewage sludge composting.

The purpose of this study was to investigate the effect of initial particle size (IPS) on the environmental parameters and heavy metal speciation during sludge composting. Three piles were conducted: fine material (FM, screen underflow), coarse material (CM, oversize product), and mixed material (MM, mix FM and CM in 1:1). Results showed that the temperature trends of the three piles in different layers were highly repeatable during the thermophilic period. With the decrease of IPS, the heating rate and the highest temperature of the pile increased, the thermophilic period was prolonged, and the highest temperature area in the pile shifted to a lower layer. It also promoted the organic matter degradation, compost maturation, and nitrogen fixation effect. Composting had a good effect on the passivation of heavy metals, especially Cd, Cu, and Pb. The passivation effect on Cd and Cu was FM > CM > MM, and on Pb was CM > FM > MM. Fourier transform infrared spectroscopy, excitation-emission matrix, and thermogravimetric thermal analysis indicated that FM had the highest content of aromatic structure and humic-like substance on D40. The redundancy analysis revealed that MM was beneficial to improve the internal uniformity during composting.

Degradation kinetics of rutin encapsulated in oil-in-water emulsions: impact of particle size.

Rutin is a natural bioactive flavonoid that is poor in water solubility and chemical stability. Encapsulation can be used to protect bioactive molecules from chemical or physical decomposition during food processing and storage. Thus, the effect of initial particle size on the ability of oil-in-water emulsions to retain rutin during storage was investigated. Rutin was encapsulated in oil-in-water emulsions with different mean surface-weighted diameters: d3,2 =0.56 μm (small), 0.73 μm (medium), and 2.32 μm (large). As expected, the resistance of the emulsions to coalescence and creaming during storage increased as the particle size decreased due to weakening of the colloidal and gravitational forces acting on the droplets. The concentration of rutin in the emulsions decreased during storage (28 days), which was mainly attributed to photodegradation of the flavonoid. The loss of rutin from the emulsions during storage was fitted using a second-order equation. The rutin degradation rate constant k decreased and the half-life t1/2 increased with decreasing droplet size, which was attributed to the stronger encapsulation and light scattering by smaller oil droplets reducing the amount of light that can penetrate into the emulsions. This study has important implications for the design of more efficacious emulsion-based delivery systems for incorporating health-promoting nutraceuticals into foods. © 2022 Society of Chemical Industry.

Fabrication and Characterization of Nanostructured Rock Wool as a Novel Material for Efficient Water-Splitting Application.

Rock wool (RW) nanostructures of various sizes and morphologies were prepared using a combination of ball-mill and hydrothermal techniques, followed by an annealing process. Different tools were used to explore the morphologies, structures, chemical compositions and optical characteristics of the samples. The effect of initial particle size on the characteristics and photoelectrochemical performance of RW samples generated hydrothermally was investigated. As the starting particle size of ball-milled natural RW rises, the crystallite size of hydrothermally formed samples drops from 70.1 to 31.7 nm. Starting with larger ball-milled particle sizes, the nanoparticles consolidate and seamlessly combine to form a continuous surface with scattered spherical nanopores. Water splitting was used to generate photoelectrochemical hydrogen using the samples as photocatalysts. The number of hydrogen moles and conversion efficiencies were determined using amperometry and voltammetry experiments. When the monochromatic wavelength of light was increased from 307 to 460 nm for the manufactured RW>0.3 photocatalyst, the photocurrent density values decreased from 0.25 to 0.20 mA/mg. At 307 nm and +1 V, the value of the incoming photon-to-current efficiency was ~9.77%. Due to the stimulation of the H+ ion rate under the temperature impact, the Jph value increased by a factor of 5 when the temperature rose from 40 to 75 °C. As a result of this research, for the first time, a low-cost photoelectrochemical catalytic material is highlighted for effective hydrogen production from water splitting.

Effect of initial particle size on grain microstructure of textured ferroelectric ceramics: A phase-field method and brush technique

A phase-field model was employed to simulate the grain microstructure evolution of the textured ceramics. Textured KSr2Nb5O15 (KSN) ceramics were chosen as the research object and prepared by using acicular KSN particles as raw materials. A method combining the brush technique with the rolling process was proposed for the directional arrangement of the acicular particles. The effects of the initial particle length distribution and diameter on the grain growth behavior and electrical properties were investigated. It was found the influence of the initial particle length distribution on the grain growth rate mainly depended on its diameter. The use of coarse particles was beneficial to obtain a microstructure with a strongly anisotropic morphology and homogeneous grain size. The obtained KSN ceramics exhibited a high piezoelectric constant d33 of 68 pC/N and Curie temperature of 120 ℃, which was closely related to the grain microstructure.

Effect of initial particle size and various composition on the spark plasma sintering of binderless tungsten carbide

The results of studies of the kinetics of high-speed spark plasma sintering (SPS) of plasma-chemical nanosized and industrial micron tungsten carbide powders are described. During SPS the carburization of the surface layer of tungsten carbide samples takes place, which leads to differences in the phase composition and hardness of the surface and central regions of sintered ceramics. The process of SPS of tungsten carbide can be sequentially represented as a change of the following mechanisms: rearrangement of particles at lower temperatures (Stage I) → sintering of particles due to grain boundary diffusion (Stage II) → sintering due to diffusion in the crystal lattice (Stage III- 1) → sintering under conditions of intensive grain growth with an abnormally low diffusion activation energy (Stage III-2).

Effects of initial particle size on mechanical, thermal, and electrical properties of porous SiC ceramics

The effects of initial particle size and sintering atmosphere on the compressive strength and thermal and electrical conductivities of porous SiC ceramics, fabricated using α-SiC and polycarbosilane (PCS), were investigated in the porosity range of 40–54%. Generally, the mechanical strength and thermal conductivity of a porous SiC ceramic decrease as the porosity increases. However, in this study, both the compressive strength (10.7–17.4 MPa) and thermal conductivity (0.55–0.79 W/(m·K)) of porous SiC ceramics increased as the porosity increased from 40 to 54% because of the decreased pore size (1013–218 nm) and increased bonding area per unit volume as the starting particle size decreased (35–1 μm). The influence of sintering atmosphere on the compressive strength and thermal conductivity of the porous SiC ceramics was negligible, whereas the porous SiC ceramics sintered in N2 atmosphere exhibited 4–10 times higher electrical conductivities than those of the samples sintered in Ar atmosphere, which can be attributed to N doping in the PCS-derived β-SiC. These results suggest that the mechanical, thermal, and electrical properties of porous SiC ceramics can be independently tuned to a certain extent by judiciously selecting the starting particle size and sintering atmosphere. The compressive strength, thermal and electrical conductivities, and porosity of the porous SiC ceramic processed with 35 μm particles in the N2 atmosphere were 10.7 MPa, 0.58 W/(m·K), 2.2 × 10−3 Ω−1 cm−1, and 40.3%, respectively.

Compression behaviour of granules produced via twin-screw melt granulation: Effect of initial particle size on granulation efficiency

This study focuses on the impact of initial particle size on the tabletability and the deformation behaviour (i.e. plasticity) of granules produced by twin-screw melt granulation (TSMG). As model substances, three different grades of anhydrous dicalcium phosphate (aDCP) were melt-granulated with polyethylene glycol 6000 (PEG) using a twin-screw granulator. Compaction performance of the granules and the corresponding physical mixtures (PM) was evaluated by in-die and out-of-die compaction analysis. A major impact on granules deformation behaviour was found for the relation of the specific surface area of the filler material to the binder content. A relative yield pressure (YP) was introduced to describe the enhancement in plastic deformation behaviour, defined as the plasticity performance factor (PPF). Furthermore, a modified Kawakita model was used to describe the granulation efficiency, compared to a calculated physical mixture model. Granules under investigation showed an increased plastic deformation, enhanced tabletability and reduced elastic recovery (ER). The binder was shown to be finely distributed and to fill the voids between the aDCP particles (image analysis of the carbon energy dispersive X-ray maps). A small initial particle size of filler material (DI-CAFOS® A7 and A12) was more efficient than a larger particle size (DI-CAFOS® A60). A very low particle size (DI-CAFOS® A7) required the addition of 1% (w/w) colloidal silicon dioxide to enable feeding of the material into the granulator. Moreover, due to the larger surface area of these particles, a higher amount of binder was necessary to achieve a low PPF and a high tensile strength (TS).

Investigation of the effects of particle size on fragmentation during tableting.

Particle size is a critical parameter during tablet production as it can impact tabletability, flowability, and dissolution rate of the final product. The purpose of this study was to investigate the effect of initial particle size on fragmentation of pharmaceutical materials during tableting. Initial particle size fractions ranging from 0-125 to 355-500µm of dibasic calcium phosphate (DCP), lactose monohydrate, and agglomerated and non-agglomerated microcrystalline cellulose (MCC) were blended with magnesium stearate and compressed into tablets. Larger initial particle sizes were found to fragment more extensively than smaller initial particle sizes for all materials based on the particle size distributions determined by laser diffraction. DCP was found to fragment most extensively followed by lactose and both MCCs. The fragmentation degrees of DCP, lactose, agglomerated and non-agglomerated MCC reached 95, 81, 32, and 29%, respectively. These findings were further supported by an increase in specific surface area with increasing compression pressure of compressed particles. The NIR spectral baseline offset from tablets was found to increase with increasing compression pressure up to 50MPa for all materials, which was the same compression pressure range where fragmentation was observed. The NIR spectral slope from tablets as a function of compression pressure furthermore showed a similar trend as the tabletability profiles. NIR spectroscopy can thereby potentially be used as a surrogate control strategy for assessing compression related particle size changes and possibly tablet density and deformation behavior during tablet production.

Experimental investigation on size degradation of bridging material in drilling fluids

Solid particle size distribution (PSD) of drilling fluids is one of the key factors for the formation damage and lost circulation control. However, particle size degradation occurs during the long-term process of drilling fluid circulation in the wellbore, consequently resulting in severe formation damage. In this study, size degradation experiments of calcium carbonate solids in the period of drilling fluid circulation are conducted to understand the effect of initial particle size, rotation speed, shear time, fluid viscosity, temperature, pH, salinity, and solid concentration on size degradation of bridging material (BM). The size degradation rate of D90 is taken as the characterization of particle size degradation. The results show that ① the degree of size degradation sharply increases with increasing solid initial size, rotation speed, and shear time. Under the experimental conditions, size degradation rate of sample with D90 = 44.153 μm is up to 30%~40% at a rotation speed of 1000 rpm over 30 min; ② there is a critical particle size in the range 15–20 μm for size degradation over 90 min. When the particle size drops to this critical size, no size degradation occurs obviously; ③ size degradation decreases with increasing fluid viscosity; ④ fluid temperature, pH, salinity, and solid concentration have little effect on size degradation. The evaluation criterion of size degradation is established, and an empirical model is developed to calculate the size degradation. Two mechanisms of the formation damage induced by size degradation are revealed. Based on the particle size degradation, the strategy for the optimization of PSD and solid supplement is presented. We believe that this strategy will be of great significance to designing the particle size distribution of BM for drilling fluids in the field.

Effect of initial particle size on microstructure and dielectric properties of Cr/Al2O3 coatings deposited by plasma spraying

Cr/Al2O3 coatings were deposited by low-power plasma spray technology using spray-dried feedstock powders with different sized initial Cr particles. XRD results revealed that γ-Al2O3 phase formed in the process of plasma spraying. The effect of initial Cr particle size on the microstructure was investigated. It was found that the coatings deposited with larger initial Cr particles possessed denser structure and lower porosity, and the Cr clusters in these coatings were more prone to form due to the connections of adjacent metal lamellae. Moreover, the initial Cr particle size had a significant effect on the dielectric properties. The complex permittivity of as-sprayed Cr/Al2O3 coatings was evidently enhanced with increasing initial Cr particle size, which was attributed to the interfacial polarization and the formation of metallic conductive clusters.

The effect of submicron-sized initial tungsten powders on microstructure and properties of infiltrated W-25 wt.% Cu alloys

In the present work, several W-25wt% Cu alloys have been prepared through combined processes of high-energy ball-milling, liquid-phase sintering and infiltration, using the precursors of industrial copper powders with an average particle size of 50μm and tungsten powders with alternative average particle size of 8μm, 800nm, 600nm or 400nm. Microstructure characteristics, relative density, hardness and electrical conductivity of the WCu alloys were investigated to elucidate the effect of initial particle size of tungsten powders. EBSD was further utilized to reveal the orientation and grain size distribution in the WCu alloys prepared by 8μm and 400nm-sized tungsten powders. The results showed that the WCu alloy made by 400nm-sized tungsten powders exhibited excellent homogeneity for both sintered tungsten powders and grains, together with the highest relative density of 98.9%, the highest hardness of 230 HB, and good electrical conductivity of 48.7% IACS. Moreover, it also showed highly improved arc erosion and mechanical wear resistances.

Effect of Initial Aluminum Alloy Particle Size on the Damage of Carbon Nanotubes during Ball Milling.

Damage to carbon nanotubes (CNTs) during the fabrication process of CNT reinforced composites has great influence on their mechanical properties. In this study, the 2014 Al with powder sizes of 20, 9 and 5 μm was selected to study the effect of initial particle size on the damage to carbon nanotubes (CNTs) during ball milling. The result shows that for CNTs in the ball milled CNT/Al (with powder size of 20 and 9 μm) mixtures, the intensity ratio of the D band and the G band (ID/IG) first increased and then reached a plateau, mainly because most of the CNTs are embedded, to a certain extent, in the aluminum powder after milling, which could protect the CNTs from damage during further milling. While for CNTs in the ball milled CNT/Al (with powder size of 5 μm) mixture, the ID/IG ratio continues to climb from 1.31 to 2.33 with time, indicating continuous damage to the CNTs occurs during the milling. Differential scanning calorimetry (DSC) analysis demonstrates that the chemical instability increased with an increase in the damage level of CNTs, resulting in the formation of aluminum carbide (Al4C3) at a lower temperature before the melting of aluminum, which is detrimental to their mechanical properties.

Experimental investigations towards understanding important parameters in wet drum granulation of corn stover biomass

Biofeedstocks such as corn coproducts or biomass such as corn stover are typically densified in a dry process using pellet mills to enhance transportability and use as livestock feed. Our work presents data of an experimental study using a non-traditional means, wet granulation with a lab-scale rotary drum granulator to determine key parameters that affect granule properties and yield of desirable sized granules. Granules were manufactured from corn stover and two liquid coproducts from corn bioprocessing, corn steep liquor (CSL) and corn molasses (CM) by varying corn stover particle size, corn stover:coproduct blend ratio and granulation residence time. The results showed that different formulation and processing parameters affected corn stover granulation. Granulation with an initial particle size of 0.88–0.96mm (from screen size 6.4mm), low liquid level (1:4) with CM, and short residence time (0.5min) could be used to produce desirable sized granules (1.78 to 7.87mm) for ruminant livestock feed with yields of over 98%. The effect of initial particle size of corn stover particles on density of granular products was significant. Corn stover particle size also positively influenced the granule size and negatively influenced yield of desirable granules. While increased coproduct (CM and CSL) levels in the blend increased the granule particle size and density, yield of desirable granules was reduced.

Effect of initial coal particle size on coal liquefaction conversion

In coal liquefaction process initial coal particle size can be considered as one of the important process parameters. In this work, particles of coal are prepared by pulverisation and separation into different particle size ranges below 45 to 1,000 µm. Since conventional batch autoclave is not suitable for short contact time experiments, as the time required for the autoclave to reach the reaction temperature can be substantial, the liquefaction runs were investigated with a rapid injection reactor designed specifically for investigating the effect of initial particle size on liquefaction conversion. A Canadian coal was examined in a tubular bomb reactor in presence of tetralin at 400°C for a short reaction time (5 min) with pressure of 6 MPa under nitrogen atmosphere. The results indicated that total conversion obtained during the liquefaction changed according to the different particle size, and optimum particle size (150-212 µm) was detected for the liquefaction condition. [Received: November 27, 2014; Accepted: August 22, 2015]

Exploring suitable ZSM-5/MCM-41 zeolites for catalytic cracking of n-dodecane: Effect of initial particle size and Si/Al ratio

In this study, various ZSM-5/MCM-41 micro/mesoporous zeolite composites have been prepared by alkali-desilication and surfactant-directed recrystallization of ZSM-5. The effects of particle size and Si/Al ratio of initial ZSM-5 zeolites on the structure and catalytic performance of ZSM-5/MCM-41 composites are studied. The results of XRD, TEM N2-adsorption–desorption, NH3-TPD and in situ FT-IR revealed that ordered hexagonal MCM-41 mesopores with 3–4nm pore size were formed around ZSM-5 crystals, and the specific surface area and mesopore volume of composites increased with increasing the Si/Al ratio of initial ZSM-5. Catalytic cracking of n-dodecane (550°C, 4MPa) showed that the ZSM-5/MCM-41 composites obtained from the high Si/Al ratio and nano-sized initial ZSM-5 zeolites exhibited superior catalytic performance, with the improvement higher than 87% in the catalytic activities and 21% in the deactivation rate compared with untreated zeolites. This could be ascribed to their suitable pore structure, which enhanced the diffusion of reactant molecules in pores of catalysts.

Effect of initial particle size and densification on AFEX-pretreated biomass for ethanol production.

Switchgrass (SG), corn stover (CS), and prairie cordgrass (PCG) pretreated with ammonia fiber expansion (AFEX) were densified using a novel low-temperature, low-pressure densification method. Simultaneous saccharification and fermentation (SSF) and separate hydrolysis and fermentation (SHF) were performed with loose and densified AFEX-treated biomass to determine the effect of post-AFEX densification. Biomass particle size reduction before pretreatment increased 144-h SSF ethanol yields from densified material by 8-9 % although no significant differences were seen in the first 72 h. Grinding material after densification had no impact on final ethanol yields but increased production rates in the first 24-48 h. Low-pressure, post-AFEX densification had no adverse effects on SSF ethanol yields from SG or CS but reduced yields from densified PCG by 16 %. Glucose concentrations after hydrolysis (SHF) showed similar trends. Ethanol yields after SHF, however, showed that densification had no significant impact on CS or PCG but reduced final ethanol yields from SG.

Synergism and photocatalytic water splitting to hydrogen over M/TiO2 catalysts: Effect of initial particle size of TiO2

In order to study the effect of anatase/rutile phases of TiO2 on the photo-catalytic production of hydrogen (often invoked as synergism) two series of Pt/TiO2 materials were prepared. The initial phase of TiO2 in both series is anatase but their particle size is different. In one case the mean particle size of TiO2 is ca. 15–20nm (nano) and in the other it is ca. 100nm (micro). Before the deposition of Pt, the two semiconductors (nano and micro) were heated to elevated temperatures to obtain partial (and total) transformation of the anatase phase to the rutile phase (UV–vis, XRD, XPS-valence band). On this differently prepared mixed phases Pt was deposited (ca. 1at.%; corrected XPS Pt4f/Ti2p=ca. 0.05) and each series was tested for the photocatalytic production of hydrogen from water in presence of ethanol (5vol.%) as a sacrificial agent (under identical conditions). Based on rates per unit mass no synergism for hydrogen production was seen in both cases; this is in part due to the decrease in the BET surface area during the phase transformation. However, strong synergism was observed for hydrogen production rates per unit area when the initial starting semiconductor was anatase nano (while no synergism seen in the case of the micro crystals). Maximum rate observed was in the 10–30% rutile range. Possible reasons for these differences are discussed.

Effects of particle size and moisture on the compressive behavior of dense Eglin sand under confinement at high strain rates

The dynamic compressive behavior of sorted and unsorted Eglin sand (Quikrete #1961 sand quarried in Pensacola, FL) under confinement was characterized under dry or moisture conditions at strain rates near 600 s−1 using a long split Hopkinson pressure bar, respectively. The as-received unsorted sand was sorted into grain sizes of 0.60 mm, 0.50 mm, 0.42 mm, 0.30 mm, 0.212 mm, 0.15 mm, 0.106 mm and 0.053 mm. For preparation of a partially saturated sand specimen sealed in a sand specimen assembly, water was introduced to reach moisture contents of 0%, 4.2%, 8.2%, 12.4%, 14.4% and 16.5%. A sand specimen assembly was used, and sand grains were confined inside a hollow cylinder of hardened steel and capped by cemented tungsten carbide rods. The assembly was subjected to repeat manual shaking and tapping to consolidate the sand to attain a given mass density; it was then sandwiched between incident and transmission bars for compression under a high strain rate. The volumetric and deviatoric behavior of dense Eglin sand was investigated on eight sorted sand specimens and at six moisture contents. After impact, the sand was analyzed to determine the particle size distribution, which was found to follow Weibull distribution rather than Gaussian distribution. The breakage factor was found to follow a linear relationship with moisture content. The effect of initial particle size and moisture on the volumetric and deviatoric behavior of sand was discussed. The compressibility was characterized in terms of void ratio as a function of axial pressure. The specific energy absorption and shear stress–hydrostatic pressure ationships were determined for different grain sizes and moisture contents.