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Abstract A new correlation is given for the prediction of the volumetric coefficient for mass transfer ( K L a ) in stirred tanks from dispersed gas bubbles to basal salt solutions of ionic strengths representative of fermentation media. The correlation includes the effects of both the operating parameters (agitation power per unit volume and gas superficial velocity) and the physicochemical properties of the system: interfacial tension, viscosity, density, diffusion, coefficient and, in particular, ionic strength. The effect of the latter was found to be most significant in the Newtonian systems of water‐like viscosity investigated; no previous correlations have included the effect of ionic strength. K L a values were determined by using a dissolved oxygen probe to monitor the steady‐state oxygen tension in continuous flow experiments, and/or the rate of change of oxygen tension in unsteady‐state semibatch experiments. In the latter cases, results were computed by a nonlinear, least squares computer program which fitted the experimental data to a model of probe transient response characteristics. The general applicability of the model and the computational procedure was verified by comparing the results to those obtained with the same electrolyte solution in the steady‐state mode. The experiments were run over a wide range of agitation power inputs, including those typical of both soluble‐ and insoluble‐substrate fermentations. The correlation appears to be valid for both oxygen mass transfer with and without homogeneous chemical reaction in the liquid phase; in the former case, for example, sulfite oxidation, knowledge of the chemical reaction enhancement factor is required. In addition to predicting oxygen transfer capabilities, the correlation may be used for other sparingly soluble gases of interest in fermentation systems, such as methane, hydrogen, and carbon dioxide.
Robinson et al. (Sun,) studied this question.