The influence of pH on gas-liquid mass transfer in non-Newtonian fluids

Abstract

In this study, the effect of pH on the mass transfer of oxygen bubble swarms in non-Newtonian fluids was experimentally studied. The volumetric liquid side mass transfer coefficient (kLa), liquid side mass transfer coefficient (kL), and specific interfacial area (a) were investigated. The pH was regulated by the addition of hydrochloric acid and sodium hydroxide (NaOH). It was found that the kLa increased with the gas flow rate increasing and decreased with the apparent viscosity of the liquid increasing. In the case of pH < 7, a marginal effect of pH on the gas?liquid mass transfer was observed, but when pH value was higher than 7, mass transfer was promoted with the increase of pH value. Via investigating the impact of pH on kL and a, the variation of mass transfer at pH > 7 was attributed to the decomposition of the Xanthan molecular structure by the hydroxyl of NaOH.