Reactive Mass Transfer of Single NO Bubbles and Bubble Bouncing in Aqueous Ferric Solutions – A Feasibility Study

Abstract

Reactive bubble columns are widely used in the chemical, petrochemical, biochemical and metal industries. While the reactive mass transfer around a single spherical shaped bubble is quite well described in literature, the influence of hydrodynamic interactions, such as bubble bouncing or coalescence on mass transfer – with and without chemical reaction – is not well understood. As to this, high resolution simulations and sophisticated experimental analysis based on high-speed camera images and local color changes gives a new firm basis. In this work, a new system is presented, based on Nitric Oxide (NO) gas absorbed in a FeII-solution. The reaction rate can be adjusted by the addition of ligands and the resulting local color change is detected. The impact of the colliding bubbles leads to a deformation of the bubble shapes and creates a fast movement of the bubble interfaces, which, finally, leads to an increased mass transfer. The results of five tested ligands reveal the high potential of the reactive FeII(NO) system to investigate basic phenomena affecting yield and selectivity of mixing-sensitive chemical reactions.