Effect of Impeller Shape on Solid Particle Suspension

Rieger, F.; Jirout, Tomáš; Ceres, D.; Seichter, Pavel

doi:10.2478/cpe-2013-0012

Cited by 6 publications

(3 citation statements)

References 6 publications

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“…A hydrofoil impeller was ultimately chosen due to their ability to promote particle resuspension and homogenize the bulk fluid, both of which are classic problems with the USP II dissolution apparatus. − Figure D1 (supplemental section D) shows the hydrofoil impeller in detail that was used for the UTLAM diffusion cell studies in this report. The volume of the donor phase was chosen to cover the hydrofoil blades completely, yet reduce the volume to increase the membrane surface area relative to volume.…”

Section: Methodsmentioning

confidence: 99%

Ultrathin, Large-Area Membrane Diffusion Cell for pH-Dependent Simultaneous Dissolution and Absorption Studies

et al. 2020

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Preclinical evaluation of modern oral dosage forms requires more advanced in vitro devices as the trend of selecting low solubility, high permeability compounds for commercial development continues. Current dissolution methodologies may not always be suitable for such compounds due to excessive fluid volume, high fluid shear rates, heterogeneity of shear rates, suboptimal fluid flow, and, ultimately, the lack of absorption ability (The Science of USP 1 and 2 Dissolution: Present Challenges and Future Relevance Gray Pharmaceutical Research20092612891302). Herein, a new dissolution apparatus is introduced in combination with an ultrathin, semipermeable polymer membrane that mimics human passive absorption for lipophilic compounds. The ultrathin large-area polydimethylsiloxane (PDMS) membrane (UTLAM) absorption system is designed to mimic the dissolution and passive transcellular diffusion process representing the oral absorption pathway. A simple spin-casting method was developed to fabricate the ultrathin highly uniform membranes. To minimize membrane resistance to diffusion and maximize transport across the polymer membrane, 10–40 μm PDMS membranes were successfully prepared. A new diffusion cell was designed and tested to support the UTLAM and incorporates a hydrofoil impeller for more desirable hydrodynamics and mixing, using ibuprofen as a model weak acidic drug. UTLAM permeability was sufficiently high that the aqueous boundary layer contributed to the overall permeability of the system. This diffusion cell system demonstrated that, when the aqueous diffusion layer contributes to the overall resistance to transport, the pH at which absorption is 50% of maximum (pH50%) shifts from the pK a to higher values, demonstrating why weak acid drugs can exhibit high absorption at pH’s significantly greater than their pK a. High rates of transport across the UTLAM are possible for drugs with high partition coefficients (i.e., BCS II compounds even under mostly ionized conditions), and PDMS UTLAMs may be tailored to simulate human intestinal passive absorption rates.

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Section: Methodsmentioning

confidence: 99%

Ultrathin, Large-Area Membrane Diffusion Cell for pH-Dependent Simultaneous Dissolution and Absorption Studies

et al. 2020

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“…Figure13. Dependence of the dimensionless power required to achieve the just-suspended state of particles of hydrofoil impellers TECHMIX on the dimensionless particle diameter dp/D for the mean volumetric concentration of the solid phase cv = 15%[34].…”

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confidence: 99%

Application of Theoretical and Experimental Findings for Optimization of Mixing Processes and Equipment

Jirout

Jiroutová

2020

Processes

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The homogenization of the agitated batch and ensuring the suspension of particles are the most frequently encountered requirements in terms of mixing applications. These operations are affected by the flow of the agitated batch. The geometrical parameters of the mixing system, especially the shape of the agitator blade, affect flow and circulation in the agitated batch. The present work provides a general description of the most common processes in the agitated batch (blending and particle suspension), hydrodynamic parameters (flow in agitated batches, pumping and circulation capacity of impellers) and the geometrical configurations of the mixing equipment (shape of vessel, baffle and impeller, and their mutual arrangement) that influence the process. The dimensionless process characteristics of the agitator were derived by theoretical analysis. These characteristics were applied to evaluate an extensive set of experimental data with various geometric configurations of the mixing equipment. This study shows how the flow in the agitated batch, caused by the pumping and circulating effects of the agitators, affects the parameters and energy efficiency of these processes, depending on the geometric configuration of the mixing equipment. Moreover, the benefits of the hydrofoil impellers used for these mixing processes are presented.

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“…The power curve method and direct calculation method agreed with the hypothesis of K s , being independent of the flow index. The effect of impeller shape on off-bottom particle suspension was also investigated by Rieger et al [10]. Based on numerous measurements, empirical correlations were proposed for the just-suspended impeller speeds for various impeller types.…”

Section: Introductionmentioning

confidence: 99%

Design of Stirrer Impeller with Variable Operational Speed for a Food Waste Homogenizer

2016

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Abstract:A conceptualized impeller called KIA is designed for impact agitation of food waste in a homogenizer. A comparative analysis of the performance of KIA is made with three conventional impeller types, Rushton, Anchor, and Pitched Blade. Solid-liquid mixing of a moisture-rich food waste is simulated under various operational speeds, in order to compare the dispersions and thermal distributions at homogenous slurry conditions. Using SolidWorks, the design of the impellers employs an Application Programming Interface (API) which acts as the canvas for creating a graphical user interface (GUI )for automation of its assembly. A parametric analysis of the homogenizer, at varying operational speeds, enables the estimation of the critical speed of the mixing shaft diameter and the deflection under numerous mixing conditions and impeller configurations. The numerical simulation of the moisture-rich food waste (approximated as a Newtonian carrot-orange soup) is performed with ANSYS CFX v.15.0. The velocity and temperature field distribution of the homogenizer for various impeller rotational speeds are analyzed. It is anticipated that the developed model will help in the selection of a suitable impeller for efficient mixing of food waste in the homogenizer.

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Effect of Impeller Shape on Solid Particle Suspension

Cited by 6 publications

References 6 publications

Ultrathin, Large-Area Membrane Diffusion Cell for pH-Dependent Simultaneous Dissolution and Absorption Studies

Ultrathin, Large-Area Membrane Diffusion Cell for pH-Dependent Simultaneous Dissolution and Absorption Studies

Application of Theoretical and Experimental Findings for Optimization of Mixing Processes and Equipment

Design of Stirrer Impeller with Variable Operational Speed for a Food Waste Homogenizer

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