Carbon Soot-Ionic Surfactant Mixed Layers at Water/Air Interfaces

An experimental study is here presented on the properties of aqueous dispersions containing carbon nanoparticles and different ionic surfactants which can modify the degree of hydrophobicity/philicity of particles favoring their transfer from the dispersion bulk to the interfacial layer. Aim of this work is to understand the particle-surfactant and particle-fluid interface interactions and their effect on those macroscopic surface properties of the mixed systems which are expected related to the stability and structure of the respective particle stabilized foams. To this purpose a systematic characterization of dispersions have been carried out, based on surface tension measurement against the surfactant concentration, using a drop Profile Analysis Tensiometer (PAT). These results have been crossed with the characterization of the bulk dispersion by Dynamic Light Scattering (DLS) and zeta-potential measurements to check the effects of surfactant on the particle aggregation and on the particle surface charge, respectively. The stability of the foams obtained with the same compositions has been also investigated and correlated to the other surface and bulk properties.