Mass transfer in aerated culture media combining mixed electrolytes and glucose
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RESEARCH PAPER
Mass transfer in aerated culture media combining mixed electrolytes and glucose Oscar R. Góngora‑García1 · Gloria Aca‑Aca1 · Sergio A. Baz‑Rodríguez1 Received: 2 February 2020 / Accepted: 7 August 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The combined effects of mixed electrolyte species and glucose on oxygen transfer were studied in a bubble column with aqueous solutions. Of particular interest was the presence of electrolytes containing ions which are prone to present solute– solute interactions or to crystallize. Without and at low concentration of glucose (≤ 5 g/L), the increasing concentration of electrolytes (nominal ionic strength: 0–0.43 M), up to a critical value, enhanced the volumetric mass transfer coefficient (k La) and the availability of specific interfacial area (a), due to the inhibition of bubble coalescence. As the glucose concentration increased (10–40 g/L), the enhancing effects of electrolytes were gradually lost. The glucose interacted with electrolytes, reducing their ability to inhibit coalescence and to enhance the kLa. Salt crystallization occurred independently of the addition of glucose; however, it did not have significant effect on mass transfer. Finally, the changes in physicochemical properties were highly collinear with composition variables. Keywords Mass transfer · Mixed electrolytes · Glucose · Salt precipitation · Bubble column bioreactor Abbreviations a Specific interfacial area (m2 of area/m3 of liquid phase) cO2,G Molar concentration of oxygen in the gas phase (mol/m3) cO2,G,0 Concentration of oxygen entering at the inlet chamber below the diffuser (mol/m3) cO2,L Molar concentration of oxygen in the liquid phase (mol/m3) d32 Sauter mean bubble diameter (m) dbi Equivalent diameter of a bubble with the same volume as a sphere (m) E Major axis of bubbles considering an oblate ellipsoidal shape (m) e Minor axis of bubbles considering an oblate ellipsoidal shape (m) ISN Nominal ionic strength of aqueous electrolyte solutions (M) ISEff Effective ionic strength of aqueous electrolyte solutions (M) * Sergio A. Baz‑Rodríguez [email protected] 1
Facultad de Ingenieria Quimica, Universidad Autonoma de Yucatan, Campus de Ciencias Exactas e Ingenierias, 97203 Mérida, YUC, Mexico
kL Mass transfer coefficient of the liquid side for the oxygen (m/s) kLa Volumetric mass transfer coefficient for gas–liquid oxygen transport (s−1) KO2-GL Henry constant for oxygen in aqueous media (dimensionless) L Height of the gas–liquid mixture above the diffuser (m) t Time coordinate (s) Qair Volumetric air flow entering to the column (m3/s) Vin Volume of the gas inlet chamber of the bubble column below the diffuser (m3) VL Initial volume of stagnant liquid in the bubble column (m3) vSG Gas superficial velocity (m/s) vslip Slip velocity between liquid and gas phases (m/s) z Axial coordinate with origin in the diffuser (m) Greek symbols ∆V Change of volume due to the sparging of gas through the liquid (m3) εG Gas ho
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