Gas–Liquid Mass Transfer around a Rising Bubble: Combined Effect of Rheology and Surfactant

Abstract

The influence of viscosity and surface tension on oxygen transfer was investigated using planar laser-induced fluorescence with inhibition (PLIF-I). The surface tension and the viscosity were modified using Triton X-100 and polyacrylamide, respectively. Changes in the hydrodynamic parameters of millimetric bubbles were identified, and transfer parameters were calculated. The results revealed a decrease in the mass transferred in the presence of a contaminant. For modified viscosity, the decrease in mass transferred was allowed for by current correlations, but the presence of surfactant led to a sharp decrease in the liquid side mass transfer coefficient, which became even lower when polymer was added. An explanation for the gap between classical correlations and experimental values of kL is discussed, and a hypothesis of the existence of an accumulation of contaminant in the diffusion layer is proposed. This led to the possibility of a decrease in the diffusion coefficient and oxygen saturation concentration in the liquid film, explaining the discrepancy between models and experience. Adapted values of DO2 and [O2] * in this layer were estimated. This original study unravels the complexity of mass transfer from an air bubble in a complex medium.

Pseudomonas putida KT2440 endures temporary oxygen limitations

“…Here, with increasing RLs and biomass concentrations throughout the cultivation, the extent of this effect would be highly dynamic, depending on different proposed mechanisms. In addition, the presence of surfactants itself has an effect on the mass transfer, which is highly dependent on the type of surfactant and its concentration (Lebrun et al, 2021). Further, the lowered pH was…”

“…Here, with increasing RLs and biomass concentrations throughout the cultivation, the extent of this effect would be highly dynamic, depending on different proposed mechanisms. In addition, the presence of surfactants itself has an effect on the mass transfer, which is highly dependent on the type of surfactant and its concentration (Lebrun et al, 2021). Further, the lowered pH was shown to reduce growth rates of P. putida KT2440 (Demling et al, 2020), thus the oxygen demand of the cells is lower over time compared to the wild‐type, in turn potentially resulting in a higher DOT.…”

Luminescent probe synthesis for oxygen visualization technique: Application to the effect of surfactant structure on oxygen mass transfer

“…Current predicting models take the Schmidt number and the Reynolds number into account to predict the Sherwood number. It is shown in [37,42,57] that, for very concentrated solutions, the Frössling model, used for fully contaminated bubbles, overestimates the mass transfer. To explain the overestimation, the authors propose that another effect, taken into account neither by the Reynolds number nor by the Schmidt number in the bulk, inhibits mass transfer.…”

“…These techniques use a fluorophore or colored molecule as the oxygen [20,[22][23][24][25][26][27][28] or carbon dioxide [29][30][31][32][33][34][35][36] sensor. Among these techniques, Planar Laser Induced Fluorescence with Inhibition (PLIF-I) enables measurements of mass transfer from a single bubble rising in a quiescent liquid [37][38][39][40][41][42][43] and provides access to (i) its shape, velocity, and diameter, and (ii) the oxygen mass transfer coefficient and diffusion coefficient in the liquid phase, with good precision. This very powerful technique then allows hydrodynamic and mass transfer to be uncoupled.…”

Gas-liquid mass transfer characterization in a thin shrinking film at an atomization nozzle

“…The difficulty of such measurements lies in avoiding any disturbances of the liquid flow in order to measure the composition of the liquid correctly. Although many titration methods exist to quantify a given solute in a liquid, methods giving direct access to the solute quantification without liquid collection, such as Raman scattering spectroscopy, rainbow refractometry, or laser induced fluorescence, are rare or difficult to implement (Lebrun et al, 2021;Lemoine and Castanet, 2013). Liquid collection methods report the global behavior of the mass transfer process, but they lack spatial and time resolution since the liquid collector volume varies with the collection of liquid and the titration is delayed with respect to the moment of collection.…”