New insights on oxygen absorption in unsparged stirred vessels

Abstract

A combination of experimental and numerical techniques revealed subtle features of oxygen absorption in unsparged stirred vessels. It was shown that the absorption kinetics was influenced not only by the mass transfer resistance in the gas–liquid interface but also by imperfect mixing in the bulk liquid. The liquid’s viscosity and density were suggested to affect the oxygen mass transfer by influencing the turbulence both at the surface and in the bulk phase, while the modification of the surface layer through surfactant addition affected only surface turbulence. The axial dispersion model proved good in the explanation of the experimental results. For the sake of comparison, the classical stagnant film model was also tested but led to slight, yet systematic, deviations in its predictions from the experimental data.