Dual emission LIF technique for pH and concentration field measurement around a rising bubble

Mass transfer plays an important role in chemical engineering applications involving multiphase systems. Several techniques have been developed in the field to measure the global mass concentration in multiphase chemical reactors. However, because of the complexity of multiphase processes, only few techniques are able to provide local and quantitative information. In this study a dual-emission Laser Induced Fluorescent technique (LIF) has been developed to locally measure the mass transfer of a rising CO2 bubble in a quiescent fluid. Details of the pH field with an overall precision of ±0.04 pH units, dissolved CO2 concentration, and the mass transfer evolution in the bubble wake can now be measured quantitatively. It is capable to provide quantitative comparison with simulation results and as such experimental validation of multiphase CFD models.