Study on the infl uence of surface-active agents on the dynamics of thin fi lms and coalescence of drops in twophase liquid-liquid systems

Aim of project
The aim of the project is to perform comprehensive studies of liquid-liquid two-phase systems containing surface- active agents. The quality, repeatability and properties of the product (which are the main aims of novel technologies) depend to a large extend on the surface development and drop size distribution. Drop size distribution is determined by breakage and coalescence processes. The project comprises experimental study of the influence of the presence of low molecular weight surfactants (ionic and nonionic), polymeric surfactants, as well as fl ow conditions on the adsorption of surface-active agent on the drop surface, on dynamics of continuous phase film and on breakage and coalescence rates. Together with studies on drop breakage and coalescence processes, flow field will be determined (using CFD methods and Laser Doppler anemometry) to take into account the relation between turbulence and breakage and coalescence. Results of this research should contribute to better understanding of breakage and coalescence mechanisms in such complex systems. Dynamic model of film drainage based on lubrication theory will also be developed. It will take into account surface phenomena connected with the presence of surface active agents of different nature and the intermittent character of turbulence. The model should enable us to determine the regions in the stirred tank in which coalescence is privileged. It will be of great importance in scaling-up. The aim of the project is also to develop models describing coalescence efficiency, introduce them into population balance equation and to predict drop size distributions.

Expected results
The result of the project realization will be a new experimental setup and research methodology for thin films and for breakage and coalescence processes in systems containing surface active agents that should enable us to design the properties of products produced in devices of different scales.