Oxygen transfer in mechanically agitated aqueous systems containing dispersed hydrocarbon

Hassan, Ibrahim; Robinson, Campbell W.

doi:10.1002/bit.260190505

Cited by 59 publications

(46 citation statements)

References 18 publications

(4 reference statements)

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“…Correlations that account for the presence of an immiscible, organic liquid phase (Hassan and Robinson, 1977;Nielsen et al, 2003) or the presence of microbial cells (Cascaval et al, 2006;Galaction et al, 2004a;Galaction et al, 2005) have been previously proposed. Generally these correlations were developed for hydrocarbons as organic phases while in the present work the correlation was developed for a perfluorocarbon, perfluorodecalin, in the presence of inactive yeast cells.…”

Section: Correlations For Oxygen Mass Transfer Coefficientsmentioning

confidence: 99%

“…Inorganic electrolytes solutions are known to inhibit both gas bubble and oil droplet coalescence, affecting the k L a (Hassan and Robinson, 1977). The effect of using YPD medium instead of pure water in the overall k L a values was evaluated with two PFC volume fractions, 0.15 and 0.20, with the optimal geometrical conditions previously determined (1.5 dm 3 of working volume and impellers type A at Position 1), at two agitation rates (100 and 250 rpm) and at four aeration rates from 0.5 to 2.0 dm 3 Á min À1 .…”

Section: Aqueous Phasementioning

confidence: 99%

“…This parameter has been assumed to be dependent on either the agitation power per unit volume ( P/V) or the impeller rotation speed and on the gas superficial velocity (Hassan and Robinson, 1977). Scale-up is usually based on correlations of various kinds to predict k L a for specific vessel geometry.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Optimization of oxygen mass transfer in a multiphase bioreactor with perfluorodecalin as a second liquid phase

Amaral

Freire

Rocha-Leão

et al. 2007

Biotech & Bioengineering

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Oxygenation is an important parameter involved in the design and operation of mixing-sparging bioreactors and it can be analyzed by means of the oxygen mass transfer coefficient (k(L)a). The operational conditions of a stirred, submerged aerated 2-L bioreactor have been optimized by studying the influence of a second liquid phase with higher oxygen affinity (perfluorodecalin or olive oil) in the k(L)a. Using k(L)a measurements, the influence of the following parameters on the oxygen transfer rate was evaluated: the volume of working medium, the type of impellers and their position, the organic phase concentration, the aqueous phase composition, and the concentration of inactive biomass. This study shows that the best experimental conditions were achieved with a perfluorodecalin volume fraction of 0.20, mixing using two Rushton turbines with six vertical blades and in the presence of YPD medium as the aqueous phase, with a k(L)a value of 64.6 h(-1). The addition of 20% of perfluorodecalin in these conditions provided a k(L)a enhancement of 25% when pure water was the aqueous phase and a 230% enhancement when YPD medium was used in comparison to their respective controls (no perfluorodecalin). Furthermore it is shown that the presence of olive oil as a second liquid phase is not beneficial to the oxygen transfer rate enhancement, leading to a decrease in the k(L)a values for all the concentrations studied. It was also observed that the magnitude of the enhancement of the k(L)a values by perfluorodecalin depends on the biomass concentration present.

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Section: Correlations For Oxygen Mass Transfer Coefficientsmentioning

confidence: 99%

Section: Aqueous Phasementioning

confidence: 99%

See 1 more Smart Citation

Optimization of oxygen mass transfer in a multiphase bioreactor with perfluorodecalin as a second liquid phase

Amaral

Freire

Rocha-Leão

et al. 2007

Biotech & Bioengineering

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“…The addition of organic solvents to bioreactor systems has been shown to improve oxygen transfer by both enhancing the mass transfer coefficient (Hassan and Robinson, 1977), as well as the equilibrium driving force (Ho et al, 1990). The average driving force in a two-phase system is increased by adding a solvent with greater dissolved oxygen solubility than the aqueous medium.…”

Section: Introductionmentioning

confidence: 99%

A restructured framework for modeling oxygen transfer in two‐phase partitioning bioreactors

Nielsen

McLellan

2005

Biotech & Bioengineering

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This communication proposes a mechanistic modification to a recently published method for analyzing oxygen mass transfer in two-phase partitioning bioreactors (Nielsen et al., 2003), and corrects an oversight in that paper. The newly proposed modification replaces the earlier empirical approach, which treated the two liquid phases as a single, homogeneous liquid phase, with a two-phase mass transfer model of greater fundamental rigor. Additionally, newly developed empirical models are presented that predict the mass transfer coefficient of oxygen absorption in both aqueous medium and an organic phase (n-hexadecane) as a function of bioreactor operating conditions. Experimental values and theoretical predictions of mass transfer coefficients in two-phase dispersions, k(L)a(TP), are compared. The revised approach more clearly demonstrates the potential for oxygen mass transfer enhancement by organic phase addition, one of the motivations for employing a distinct second phase in a partitioning bioreactor.

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“…The effects of adding a second liquid organic phase on k L a may change, and it was shown that k L a values may increase, decrease, or remain constant, depending on the nature of the organic compound and the operating conditions [2][3][4][5][6][7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Oxygen mass transfer in a biphasic medium: Influence on the biotransformation of methyl ricinoleate into γ-decalactone by the yeast Yarrowia lipolytica

Gomes

Aguedo

Teixeira

et al. 2007

Biochemical Engineering Journal

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In this work, an empirical correlation is proposed to describe k L a as a function of operating conditions (agitation and aeration rates) and of oil and surfactant volumetric fractions in a biotransformation medium, an oil-in-water dispersion. An interaction effect between the oil and the surfactant effects was found, since oil presence increased k L a in the absence of the surfactant but had an opposite effect when Tween 80 was available in the medium. The biotransformation of methyl ricinoleate (MR) into ␥-decalactone (an aroma compound of industrial interest), by the yeast Yarrowia lipolytica, was carried out at different conditions of operation, to evaluate the influence of k L a on the production of the aroma. It was demonstrated that k L a had an influence on the aroma production; however, for the low hydrophobic substrate concentration used (1.08% v/v) and cellular density of 2.0 × 10 7 cells mL −1 , a minimal k L a value of 70 h −1 was necessary to attain the maximal aroma production.

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Oxygen transfer in mechanically agitated aqueous systems containing dispersed hydrocarbon

Cited by 59 publications

References 18 publications

Optimization of oxygen mass transfer in a multiphase bioreactor with perfluorodecalin as a second liquid phase

Optimization of oxygen mass transfer in a multiphase bioreactor with perfluorodecalin as a second liquid phase

A restructured framework for modeling oxygen transfer in two‐phase partitioning bioreactors

Oxygen mass transfer in a biphasic medium: Influence on the biotransformation of methyl ricinoleate into γ-decalactone by the yeast Yarrowia lipolytica

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