Morphology Of Solid Particles Research Articles

Optimizing the Load Distribution of the p-Xylene Oxidation Process in a Continuous Reactor

The liquid-phase oxidation of p-xylene (PX) is the key step in the purified terephthalic acid (PTA) production technology. With the improved oxidation technology and intensified competition in the PTA industry, it is crucial to develop a more efficient and energy-saving PX oxidation technology. In this work, the oxidation load distribution for two reactors was optimized through the experiment and simulation. The results showed that the temperature of the first reactor has a substantial influence on the overall PTA production. An increase in temperature in the first reactor reduced the impurity content. However, increasing the reactor or crystallizer temperature has little impact on the morphology of solid particles. Furthermore, with a fixed total residence time of the two reactors, extending the residence time of the first reactor has no impact on reducing impurities, while the reduction of impurities is observed in the second reactor.

Bulk and Surface Wettability Characteristics of Probiotic Powders in Their Compressed Disc and Packed-Bed Column Forms

Most probiotic-based products are available in powder particles under different solid-state forms. Such diversity can affect the probiotic stability, viability, and performance at different stages of processing, storage, and use. Here, we apply complementary physical chemistry techniques to characterize the bulk and surface properties of probiotic powder particles under different forms and report quantitative results of a highly concentrated multistrain reference product. The solid particle morphology, size/shape distribution, and the powder surface wettability in the compressed disc and porous packed bed forms are successively measured by sessile drop and capillary rise techniques. A complete wettability of the disc surface is observed through equilibrium contact angle measurements for various solvents, whereas the associated capillary rise data exhibit two regimes: a power law regime for the first few moments followed by a second regime, which can be described using Darcy’s law. The use of this modeling approach shows the possibility of assessing the particle-packed bed permeability and porosity. These results open a new route of the structure–activity relationship study on the impact of probiotic solid particles on their functionalities and performance in promoting health benefits, related particularly to the human and animal gut permeability. This statement also strengthens the idea of using the compressed disc technique for easily performing probiotic wettability measurements.

Fabrication of Closed-Cell Magnesium Composite Foam with Fine and High Roundness Pore Structure

Though metal foams possess excellent overall performances, its performances behave quite different due to its apparent aperture difference of pores diameter, pores roundness and significant macrostructure flaws, such as sharp edged pores and incomplete cell walls. It is meaningful to reduce macrostructure defects or improve pores structure uniformity of metal foams from the view point of practical applications. In this work, different thickening agents were added into AZ31B magnesium composite foams to balance foaming process and improve the homogeneity of pore diameter, pore roundness and cell wall integrity. The results showed that pore diameter, roundness of the pores and integrity of cell walls were obviously influenced by thickening agents. Based on a large number of experimental results, calcium granules and magnesium cerium intermediate alloy were used to control the number and morphology of solid particles in magnesium melt, and a kind of magnesium composite foams with fine roundness pores and complete cell wall structure were obtained.

Resolving the Discrepancy in Tortuosity Factor Estimation for Li-Ion Battery Electrodes through Micro-Macro Modeling and Experiment

Battery performance is strongly correlated with electrode microstructural properties. Of the relevant properties, the tortuosity factor of the electrolyte transport paths through microstructure pores is important as it limits battery maximum charge/discharge rate, particularly for energy-dense thick electrodes. Tortuosity factor however, is difficult to precisely measure, and thus its estimation has been debated frequently in the literature. Herein, three independent approaches have been applied to quantify the tortuosity factor of lithium-ion battery electrodes. The first approach is a microstructure model based on three-dimensional geometries from X-ray computed tomography (CT) and stochastic reconstructions enhanced with computationally generated carbon/binder domain (CBD), as CT is often unable to resolve the CBD. The second approach uses a macro-homogeneous model to fit electrochemical data at several rates, providing a separate estimation of the tortuosity factor. The third approach experimentally measures tortuosity factor via symmetric cells employing a blocking electrolyte. Comparisons have been made across the three approaches for 14 graphite and nickel-manganese-cobalt oxide electrodes. Analysis suggests that if the tortuosity factor were characterized based on the active material skeleton only, the actual tortuosities would be 1.35–1.81 times higher for calendered electrodes. Correlations are provided for varying porosity, CBD phase interfacial arrangement and solid particle morphology.

An Overview of Pickering Emulsions: Solid-Particle Materials, Classification, Morphology, and Applications.

Pickering emulsion, a kind of emulsion stabilized only by solid particles locating at oil–water interface, has been discovered a century ago, while being extensively studied in recent decades. Substituting solid particles for traditional surfactants, Pickering emulsions are more stable against coalescence and can obtain many useful properties. Besides, they are more biocompatible when solid particles employed are relatively safe in vivo. Pickering emulsions can be applied in a wide range of fields, such as biomedicine, food, fine chemical synthesis, cosmetics, and so on, by properly tuning types and properties of solid emulsifiers. In this article, we give an overview of Pickering emulsions, focusing on some kinds of solid particles commonly serving as emulsifiers, three main types of products from Pickering emulsions, morphology of solid particles and as-prepared materials, as well as applications in different fields.

Influence of time evolution of particle shape on rheological behavior of semisolid slurries of magnesium alloy AZ91D

To gain the insights into the influence of the morphology of solid particles on rheological behavior of semisolid metal slurries, the time evolution of Hausdorff dimensionality describing the particle morphology is deduced in order to quantitatively analyze the time evolution of the particle morphology. In consideration of the role of the liquid entrapped by non-spherical solid particles, the non-spherical solid particles with the entrapped liquid are treated as spherical solid particles, and the equivalent solid volume fraction is defined as the sum of solid volume fraction and the volume fraction of the entrapped liquid. This model could be used to analyze the rheological behavior of the semisolid metal slurries containing the non-spherical particles with Hausdorff dimensionality less than 3. Moreover, the rheological behavior of semisolid magnesium alloy AZ91D is theoretically analyzed by this model during isothermal shearing and continuous cooling. The calculated results are found coinciding with the experimental results and the calculated results also reveal that the shear rate and cooling rate could influence the rheological behavior of semisolid metal slurries by changing the morphology of solid particles except by affecting agglomeration degree.

Optimal Design of a Gas Antisolvent Recrystallization Process of Cyclotetramethylenetetranitramine (HMX) with Particle Size Distribution Model

Physical properties and characteristics of a solid particle highly depend on the particle shape and size. The Gas AntiSolvent (GAS) process is a recently developed process that can control the size and morphology of solid particles using supercritical fluids as an antisolvent to resrystallize desired products in solution. Though many lab-scale experiments with different choices of antisolvents exist, no study for the large-scale operation of such a system has been reported yet. This study proposes different design options of a GAS process for recrystallization of HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane or cyclotetramethylenetetranitramine) using CO2 as an antisolvent. A detailed mathematical model for particle size distribution is integrated into the process flow sheet model. An optimal process which includes the particle size data of product and process specifications are proposed with economic evaluation and comparison of various alternative processes.

Morphological Evolution of SCN Crystals in a Shear Flow

Morphological evolution of a transparent model succinonitrile (SCN) material during solidification was investigated in an apparatus resembling a shearing-disc viscometer. The in situ microscopic observations showed that fragmentation decreased the average particles size, but did not result in transition of dendritic to spherical morphology. At low shear rates, the degenerated dendrites and at high shear rates, the pseudo-cluster morphology was observed. It was revealed that coarsening has the most important effect on the final morphology of solid particles. The quantitative influences of shearing rate and intensity on the size and morphology of solid crystals were also discussed based on the measurements on the microstructures.

Effect of structural properties of carbon-based fuels on efficiency of direct carbon fuel cells

This research is focused on the effect of supplying solid oxide fuel cells with different graphite and carbon black powders on the cells’ efficiency. Before being tested in the fuel cell, the structures of carbon-based fuels were characterized by X-ray diffraction analysis, Raman spectroscopy, scanning electron microscopy, and thermal analysis method (DTA/TG). Total electrical conductivity measurements were also carried out for carbon samples. The relation between the structure and morphology of solid particles and their performance in direct carbon solid oxide fuel cells (DC-SOFC) was presented and discussed. It was found that structurally disordered carbon-based materials are the most promising fuels for oxidation in DC-SOFCs.

Methoxybutropate Microencapsulation by Gelatin-Acacia Complex Coacervation

Microcapsules of methoxybutropate solid particles or of an oily saturated solution of the same drug were prepared by complex coacervation between gelatin and acacia and dried with three different methods: isopropanol addition, spray-drying, and freeze-drying. Successively, microparticles were analyzed by infrared thermobalance, ultraviolet (UV) spectroscopy, optical and scanning electron microscopy, and sieves to find out parameters such as yield, moisture content, encapsulation percentage, morphology of solid particles, and particle size. Results highlighted that the most appropriate drying method for industrial purposes was spray-drying, particularly for oil-containing microcapsule formulations.

Gelatin-Acacia Complex Coacervation as a Method for Ketoprofen Microencapsulation

AbstractKetoprofen microcapsules were prepared by complex coacervation between gelatin and acacia, and dried with different methods: isopropanol addition, spray-drying, and freeze-drying, Successively, microparticles were analyzed by infrared thembalance, ultraviolet spectroscopy, optical and scanning electron microscopy, and sieves; and subjected to dissolution studies in order to examine parameters such as yield, moisture content, encapsulation percentage, morphology of solid particles, particle size, and dissolution behavior. Provided that encapsulation and drying methods did not affect ketoprofen dissolution profiles, the most appropriate drying method for industrial purposes was spray-drying.