The effect of surfactant addition on the performance of a bubble column containing a non-Newtonian liquid

The purpose of this work is to investigate how the addition of an organic surface active agent affects the characteristics of a bubble column equipped with a porous sparger and containing a non-Newtonian liquid. Water and an aqueous glycerin solution, both containing a minute amount of xanthan gum, were the non-Newtonian shear thinning liquids, while the gas phase was atmospheric air for all cases. Small amounts of the non-ionic surface active agent Triton X-100 was added to modify the surface tension of the non-Newtonian solutions. The results show that the diameter of the bubbles decreases and the transition point from the homogeneous to the heterogeneous is shifted to higher gas flow rates, when the surfactant is added. Appropriate correlations are also proposed, which take into account the liquid phase properties, the gas phase flow rate, as well as the column and sparger characteristics and predict with reasonable accuracy the transition point from the homogenous to the heterogeneous regime, the Sauter mean diameter of the bubbles and the average gas holdup. (c) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.