Investigation Of Agglomeration Research Articles

INFLUENCE OF HEATING CONDITIONS ON FORMATION AND DEVELOPMENT OF AGGLOMERATES IN A REACTIVE POROUS MEDIUM

INFLUENCE OF HEATING CONDITIONS ON FORMATION AND DEVELOPMENT OF AGGLOMERATES IN A REACTIVE POROUS MEDIUM

Investigation of Agglomeration in the Presence of Oiling Out in the Antisolvent Crystallization Process

Oiling out during the crystallization process often generates agglomeration. This research is focused on the control of agglomeration in the antisolvent crystallization of the propylparaben-ethanol-water system in the presence of oiling out, that is, the liquid-liquid phase separation phenomenon. Crystallization trajectories were designed to start from a homogeneous solution with different initial concentrations of propylparaben in ethanol, crossing the liquid-liquid phase separation region in the ternary phase diagram by adding the antisolvent of water. A combination of process analytical technology tools, such as focused beam reflectance measurement, particle visual monitoring, and attenuated total reflectance ultraviolet/visible, enabled the detection of the different stages of the oiling out crystallization process, including the droplet formation of the dispersed phase, prenucleation, nucleation, and crystal growth both in the liquid-liquid phase-separated system and in the homogeneous solution. The crystals tended to form normally at higher initial concentrations of propylparaben while tending to agglomerate at a lower initial concentration. Crystallization experiments were also performed with the addition of sonication, with variation in sonication start time, duration, and power. The results showed that ultrasound could reduce the agglomeration dependent on the initial application time. The mechanism of crystallization and agglomeration in oiling out was discussed.

Effects of pin diameter and number of cycles on microstructure and tensile properties of friction stir fabricated AA1050-Al2O3 nanocomposite

Nanocomposites of Al-Al2O3 are fabricated by means of friction stir processing (FSP). Effects of pin diameter and number of FSP cycles on tensile properties of the nanocomposites are investigated and the variations are correlated to the evolution of microstructure and distribution of nanoparticles in addition to agglomeration of Al2O3 nanoparticles. Investigation of agglomeration has been considered as an indirect indication for efficiency of the process for distribution of nanoparticles. The ductility of the nanocomposite is found to improve due to grain refinement during FSP. However, the ductility is likely to degrade if Al2O3 particles agglomerate and form coarse particles. The composite fabricated using the 6-mm pin indicates the maximum ductility which is attributed to formation of fine grain structure and efficient distribution of nanoparticles in the composite. Although, the grain structure in the composite fabricated using 8-mm pin is well refined, this sample shows significantly lower ductility with respect to the other samples. This was attributed to formation of coarse agglomerated particles. The second pass of FSP is found to slightly improve ductility and strength in composites fabricated using 4- and 6-mm pins but enforce significant improvements in the one with 8-mm pin. This is indeed because the second pass results in significant change in the distribution of nanoparticles or agglomerated particles in the latter case and negligible in the former ones. Grain structure and nanoparticle distribution and agglomeration can all affect the fracture surface of the tensile specimens of the fabricated nanocomposite to be ductile or brittle.

Investigation of agglomeration and sedimentation of PEFC electrode slurries by a laminated microfluidic device

Investigation of agglomeration and sedimentation of PEFC electrode slurries by a laminated microfluidic device

Investigation of Agglomeration and Sedimentation of PEFC Catalyst Inks by a Laminated Microfluidic Device

Investigation of Agglomeration and Sedimentation of PEFC Catalyst Inks by a Laminated Microfluidic Device

Investigation of Agglomeration and Defluidization during Spouted-Bed Gasification of High-Sodium, High-Sulfur South Australian Lignite

The mechanisms of agglomeration and defluidization during the fluid-bed gasification of an Australian low-rank coal are investigated. Experiments were conducted in a 77 mm inner diameter spouted-bed gasifier with a high-sodium, high-sulfur coal from the Lochiel deposit in South Australia. The effect of the bed temperature, air/fuel ratio, and superficial velocity on the stable operation of the spouted bed over a 4 h period was investigated. The results of this study indicate that stable bed operation is governed by a “high-temperature defluidization limit”, suggesting that defluidization can be delayed or avoided by operating the bed with high superficial velocity and/or low bed temperatures. In experiments that resulted in agglomeration and in some experiments that did not, the average particle size within the bed material had increased, which was mainly attributed to coating of mineral particles. These coated particles were observed to be more prevalent in runs that led to defluidization of the bed. Par...

Influence of oxalic acid on the kinetics of Al(OH) 3 growth from caustic soda solutions

Crystallization of Al(OH) 3 from caustic soda solutions is an important part of the Bayer process for alumina production. Nucleation, agglomeration and crystal growth processes occur simultaneously during crystallization of Al(OH) 3 and have different effects on the final product. In this study, we have investigated the influence of oxalic acid on the kinetics of Al(OH) 3 crystal growth. The results have shown that the overall growth rate of Al(OH) 3 crystals increased with increase of temperature of crystallization and decreased with caustic soda concentration, both in the presence and absence of oxalic acid. However, the presence of oxalic acid reduces the overall growth rate of Al(OH) 3 compared to the overall crystal growth rate from the pure caustic soda solutions, and the reduction is greater as the concentration of oxalic acid increased. In other words, the oxalic acid has the inhibitory influence on Al(OH) 3 crystal growth. The effectiveness of the oxalic acid on the Al(OH) 3 growth can be represented through a modified Langmuir adsorption isotherm, and adsorption of admixture on the surface of growing Al(OH) 3 crystals is favoured with a decrease in temperature and with an increase in oxalic acid concentration. Relatively high crystal growth rates (between 8 and 22 μm/h) result from an agglomeration process that could not be prevented because of the presence of small seed Al(OH) 3 particles and the newly formed Al(OH) 3 particles through the nucleation process. Investigation of agglomeration and nucleation processes has shown that agglomeration increased with increasing temperature and decreasing caustic soda concentration, while the nucleation process can be increased with decreasing temperature and caustic soda concentration.