Experimental characterisation of the adsorption dynamics and surfactant transfer in liquid-liquid system

The study and characterisation of the equilibrium and dynamics adsorption properties in liquid-liquid systems is of fundamental importance in emulsion science and technology. These systems are characterised from the partitioning of the surfactant between the two liquid phases. Thus the experimental approaches and models developed for liquid-vapour interfaces cannot be straightforward applied to liquid-liquid interfaces, deserving specific considerations. Two techniques are particularly suitable for the investigation of adsorption dynamics at liquid-liquid interfaces: the Drop Shape (DS) and the Capillary Pressure tensiometry (CP). Here a brief description of these techniques is given and their effectiveness is exemplified. In particular recent results about the measurement of the dilational visco-elasticity of adsorption layers at liquid-liquid, obtained by the PAT1 DS tensiometer from Sintech (Berlin) and by the CP tensiometer, developed at CNR-ICFAM (Genoa), are given.