Effect of the Internal Mass Transfer Resistance on the Ni/Al2O3 Deactivation by Thiophene

1993 ◽  
pp. 2547-2550
Author(s):  
S. Zrncevic ◽  
V. Tomasic
Keyword(s):  
Mass Transfer ◽  
Internal Mass ◽  
Mass Transfer Resistance ◽  
Transfer Resistance ◽  
Internal Mass Transfer

Structure and microbial composition of nitrifying microbial aggregates and their relation to internal mass transfer effects

2004 ◽  
Vol 50 (10) ◽  
pp. 213-220 ◽  
Author(s):  
B.-M. Wilén ◽  
D. Gapes ◽  
L.L. Blackall ◽  
J. Keller
Keyword(s):  
Mass Transfer ◽  
In Situ Hybridisation ◽  
Gas Analysis ◽  
Microbial Consortia ◽  
Fish Analysis ◽  
Fluorescence In Situ Hybridisation ◽  
Internal Mass ◽  
Microbial Composition ◽  
Transfer Resistance ◽  
Internal Mass Transfer

This paper presents an analysis of the structure and microbial composition of nitrifying aggregates, formed as either flocs or granules, in sequencing batch reactors (SBR) operated with a high ammonium load. The structure and microbial community of the aggregates was determined by fluorescence in situ hybridisation (FISH). The aggregate structure and size was related to mass transfer limitations observed by measurements of OURs measured by either a titrimetric and off-gas analysis sensor (TOGA) or by microsensors. The FISH analysis showed that the spatial arrangement of the microbial consortia correlated well with the oxygen gradients inside the aggregates. In the larger aggregates, the ammoniumand nitrite-oxidising bacteria were mainly concentrated to the outer 100–200 μm, whereas in the floc system, the bacteria were distributed throughout the entire aggregate. This indicates that the internal mass transfer resistance is considerably larger when the aggregate size increases which is directly supported by TOGA measurements.

Analysis of Heat and Mass Transfer Between a Desiccant-Air System in a Packed Tower

1987 ◽  
Vol 109 (2) ◽  
pp. 89-93 ◽  
Author(s):  
P. Gandhidasan ◽  
M. Rifat Ullah ◽  
C. F. Kettleborough
Keyword(s):  
Mass Transfer ◽  
Gas Phase ◽  
Heat And Mass Transfer ◽  
Packing Material ◽  
Mass Transfer Resistance ◽  
Liquid Desiccant ◽  
Governing Equations ◽  
Packed Tower ◽  
Transfer Resistance ◽  
Steady State Model

Heat and mass transfer analysis between a desiccant-air contact system in a packed tower has been studied in application to air dehumidification employing liquid desiccant, namely calcium chloride. Ceramic 2 in. Raschig rings are used as the packing material. To predict the tower performance, a steady-state model which considers the heat and mass transfer resistances of the gas phase and the mass transfer resistance of the liquid phase is developed. The governing equations are solved on a digital computer to simulate the performance of the tower. The various parameters such as the effect of liquid concentration and temperature, air temperature and humidity and the rates of flow of air and liquid affecting the tower performance have been discussed.

Use of macromolecular compounds to control internal mass transfer in a granular material

1982 ◽  
Vol 43 (6) ◽  
pp. 1389-1394
Author(s):  
A. M. Abramets ◽  
I. I. Lishtvan ◽  
N. V. Churaev
Keyword(s):  
Mass Transfer ◽  
Granular Material ◽  
Internal Mass ◽  
Internal Mass Transfer

scholarly journals Modeling of the adsorption kinetics of zinc onto granular activated carbon and natural zeolite

2006 ◽  
Vol 71 (8-9) ◽  
pp. 957-967 ◽  
Author(s):  
Ljiljana Markovska ◽  
Vera Meshko ◽  
Mirko Marinkovski
Keyword(s):  
Mass Transfer ◽  
Activated Carbon ◽  
Simulation Study ◽  
Natural Zeolite ◽  
Granular Activated Carbon ◽  
Model Parameters ◽  
Mass Transfer Resistance ◽  
External Mass Transfer ◽  
Transfer Resistance ◽  
Kinetics Of

The isotherms and kinetics of zinc adsorption from aqueous solution onto granular activated carbon (GAC) and natural zeolite were studied using an agitated batch adsorber. The maximum adsorption capacities of GAC and natural zeolite towards zinc(II) from Langmuir adsorption isotherms were determined using experimental adsorption equilibrium data. The homogeneous solid diffusion model (HSD-model) combined with external mass transfer resistance was applied to fit the experimental kinetic data. The kinetics simulation study was performed using a computer program based on the proposed mathematical model and developed using gPROMS. As the two-mass transfer resistance approach was applied, two model parameters were fitted during the simulation study. External mass transfer and solid phase diffusion coefficients were obtained to predict the kinetic curves for varying initial Zn(II) concentration at constant agitation speed and constant adsorbent mass. For any particular Zn(II) - adsorbent system, k f was constant, except for the lowest initial concentration, while D s was found to increase with increasing initial Zn(II) concentration.

Sign in / Sign up

Export Citation Format

Share Document