Advances in Characterization of Gas Transport in Concrete: Determination of Oxygen Diffusion Coefficient from Permeability Coefficient and Porosity

p-toluenesulphonic acid degradation by Comamonas testosteroni T-2 in multi-species biofilms was studied in a fixed bed biofilm reactor. The polypropylene static mixer elements (Sulzer Chemtech Ltd., Switzerland) were used as a support matrix for biofilm formation. Biofilm respiration was estimated using the dynamic gassing-out oxygen uptake method. A strong relation between oxygen uptake and reactor degradation efficiency was observed, because p-toluenesulphonate degradation is a strictly aerobic process. This technique also allowed us to estimate the thickness of the active layer in the studied system. The mean active thickness was in order of 200 μm, which is close to maximum oxygen penetration depth in biofilms. A transient mathematical model was established to evaluate oxygen diffusitivity in non-steady-state biofilms. Based on the DO concentration profiles, the oxygen diffusion coefficient and the maximum respiration activity were calculated. The oxygen diffusion coefficient obtained (2 10−10-1.2 10−9 m2 s−1) is in good agreement with published values. The DO diffusion coefficient varied with biofilm development. This may be, most likely, due to the biofilm density changes during the experiments. The knowledge of diffusivity changes in biofilms is particularly important for removal capacity estimation and appropriate reactor design.

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Oxygen diffusion coefficient and solubility inn-hexadecane

Biotechnology and Bioengineering ◽

10.1002/bit.260340914 ◽

1989 ◽

Vol 34 (9) ◽

pp. 1221-1224 ◽

Cited By ~ 47

Author(s):

Lu-Kwang Ju ◽

Chester S. Ho

Keyword(s):

Diffusion Coefficient ◽

Oxygen Diffusion ◽

Oxygen Diffusion Coefficient

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Electronic/Ionic Conductivity and Oxygen Diffusion Coefficient af the Sr-Fe-Co-O System

MRS Proceedings ◽

10.1557/proc-393-49 ◽

1995 ◽

Vol 393 ◽

Cited By ~ 18

Author(s):

B. Ma ◽

J.-H. Park ◽

C. U. Segre ◽

U. Balachandran

Keyword(s):

Diffusion Coefficient ◽

Ionic Conductivity ◽

Oxygen Diffusion ◽

Ionic Conductivities ◽

Transference Number ◽

Transference Numbers ◽

Oxygen Diffusion Coefficient ◽

Ionic Transference Number ◽

Local Fitting ◽

Oxide Ion

ABSTRACTOxides in the Sr-Fe-Co-O system exhibit both electronic and ionic conductivities. Recently, the Sr-Fe-Co-O system attracted great attention because of its potential to be used for oxygen-permeable membranes that can operate without electrodes or external electrical circuitry. Electronic and ionic conductivities of two compositions of the Sr-Fe-Co-O system, named SFC-1 and SFC-2, have been measured at various temperatures. The electronic transference number is much greater than the ionic transference number in SFC-1, whereas the electronic and ionic transference numbers are very similar in SFC-2. At 800°C, the electronic and ionic conductivities are ≈76 and ≈4 S•cm−1, respectively, for SFC-1; whereas, for SFC-2, the electronic and ionic conductivities are ≈10 and ∼1 S•cm−1, respectively. By performing a local fitting to the equation σ • T = Aexp(-Ea / kT), we found that the oxide ion activation energies are 0.92 and 0.37 eV, respectively, for SFC-1 and SFC-2. The oxygen diffusion coefficient of SFC-2 is ≈ 9 x 10−7cm2/sec at 900°C.

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