scholarly journals Hierarchical Mass Transfer Analysis of Drug Particle Dissolution, Highlighting the Hydrodynamics, pH, Particle Size, and Buffer Effects for the Dissolution of Ionizable and Nonionizable Drugs in a Compendial Dissolution Vessel

2020 ◽  
Vol 17 (10) ◽  
pp. 3870-3884 ◽  
Author(s):  
Niloufar Salehi ◽  
Jozef Al-Gousous ◽  
Deanna M. Mudie ◽  
Gordon L. Amidon ◽  
Robert M. Ziff ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Particle Size ◽  
Drug Particle ◽  
Particle Dissolution ◽  
Buffer Effects

Mass transfer impacts in flocculent and granular biomass from SBR systems

2004 ◽  
Vol 50 (10) ◽  
pp. 203-212 ◽  
Author(s):  
D. Gapes ◽  
B.-M. Wilén ◽  
J. Keller
Keyword(s):  
Mass Transfer ◽  
Particle Size ◽  
Oxygen Uptake ◽  
Activated Sludge ◽  
Uptake Rate ◽  
Oxygen Uptake Rate ◽  
Batch Reactor ◽  
Average Particle Size ◽  
Gas Analysis ◽  
Average Particle

An experimental study was conducted to describe mass transfer impacts within nitrifying aggregates sourced from sequencing batch reactor (SBR) activated sludge systems. Flocculent and granular sludge with high nitrification activity was obtained in two laboratory SBR systems, supplied with a synthetic, ammonium-based feed. The flocculent biomass was fractionated using a sieving procedure, in order to obtain biomass fractions with different particle size distributions. The oxygen uptake rate (OUR) response to changes in dissolved oxygen concentration was measured under highly controlled conditions in a titrimetric and off-gas analysis (TOGA) sensor, and the results used to assess mass transfer effects. As the average particle size of the biomass increased, mass transfer limitations were found to increase significantly. Empirically fitted, apparent KS,O2 values were demonstrated to be highly dependent on particle size, and reflect the mass transfer limitations occurring in the aggregates within a given system. Such parameters thus have little to do with the actual biokinetic parameter from which they are derived. The results obtained from the TOGA sensor study were consistent with those obtained from a microelectrode study on the same nitrifying granules. Together, these studies add considerable weight to the conclusion that consideration of external and internal mass transfer limitations is vital to the accurate description of activated sludge treatment processes, particularly those with a high oxygen uptake rate.

scholarly journals From nucleation and coarsening to coalescence in metastable liquids

2020 ◽  
Vol 378 (2171) ◽  
pp. 20190247 ◽  
Author(s):  
Dmitri V. Alexandrov ◽  
Irina V. Alexandrova
Keyword(s):  
Mass Transfer ◽  
Particle Size ◽  
Distribution Function ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Ostwald Ripening ◽  
Intermediate Stage ◽  
Size Distribution Function ◽  
The Right ◽  
Transfer Mechanisms

The transition of a metastable liquid (supersaturated solution or supercooled melt) occurring from the intermediate stage (where the crystals nucleate and grow) to the concluding stage (where the larger particles evolve at the expense of the dissolution of smaller particles) is theoretically described, with allowance for various mass transfer mechanisms (reaction on the interface surface, volume diffusion, grain-boundary diffusion, diffusion along the dislocations) arising at the stage of Ostwald ripening (coalescence). The initial distribution function (its ‘tail’) for the concluding stage (forming as a result of the evolution of a particulate assemblage during the intermediate stage) is taken into account to determine the particle-size distribution function at the stage of Ostwald ripening. This modified distribution function essentially differs from the universal Lifshitz–Slyozov (LS) solutions for several mass transfer mechanisms. Namely, its maximum lies below and is shifted to the left in comparison with the LS asymptotic distribution function. In addition, the right branch of the particle-size distribution lies above and is shifted to the right of the LS blocking point. It is shown that the initial ‘tail’ of the particle-size distribution function completely determines its behaviour at the concluding stage of Ostwald ripening. The present theory agrees well with experimental data. This article is part of the theme issue ‘Patterns in soft and biological matters’.

PEMBUATAN PUPUK ORGANIK CAIR DARI KOTORAN SAPI MENGGUNAKAN KOLOM FIXED BED SECARA KONTINYU

EKUILIBIUM ◽  
2012 ◽  
Vol 11 (2) ◽  
Author(s):  
Paryanto Paryanto
Keyword(s):  
Mass Transfer ◽  
Particle Size ◽  
Soil Degradation ◽  
Organic Fertilizer ◽  
Fixed Bed ◽  
Cow Manure ◽  
Volumetric Mass Transfer Coefficient ◽  
Fixed Bed Column ◽  
A Value ◽  
Bed Height

<p><strong><em>Abstract:</em></strong><em> Nowadays, organic fertilizer is more interesting than anorganic fertilizer, because it doesn’t cause soil degradation and the crops are healthier to be consumed. Manure is the most familiar as an organic fertilizer. This study dealt with producing of liquid organic fertilizer from cow manure in fixed bed column reactor. The reactor operated at 30 <sup>o</sup>C, 40 cmHg and 19.2 mL/s of solvent flowrate. The aim of this study was to find correlation between bed height of manure in column, particle size of manure, concentration of fertilizer and volumetric mass transfer coefficient </em>(<em>k<sub>c</sub>a</em>)<em>. The highest of k<sub>c</sub>a value was obtained at 25 cm of bed height, it was 0.0014 s<sup>-1</sup>. The result shows that bed height of manure is linier to k<sub>c</sub>a. On the other hand, particle size of manure doesn’t give much influence of k<sub>c</sub>a.</em></p><p><strong><em> </em></strong><strong><em>Keywords</em></strong><strong>:</strong><em> extraction, fixed bed, cow manure, liquid organic fertilizer, volumetric mass transfer </em><em>coefficient</em></p>

Effect of drug particle size in ultrasound compacted tablets

2006 ◽  
Vol 310 (1-2) ◽  
pp. 168-174 ◽  
Author(s):  
Mónica Millán ◽  
Isidoro Caraballo
Keyword(s):  
Particle Size ◽  
Drug Particle
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