Interfacial properties of carbon particulate-laden liquid interfaces and stability of related foams and emulsions

Aqueous dispersions of carbon black and carbon soot containing the cationic surfactant CTAB have been investigated from the point of view of dynamic interfacial tension and surface dilational rheology. In addition the features and stability of emulsions and foams formed from these dispersions have been studied and correlated with the interfacial properties. The results show an interaction of the carbonaceous particles with the CTAB in determining the interfacial properties of dispersions. The investigation on emulsion and foam stability shows a synergetic effect of particles and surfactant in providing water-in-hexane emulsions stable over several months. This synergetic effect, even evident for emulsions, is instead less effective for foams. Results for emulsions and foams stability can be partially correlated with the observations on interfacial properties. Since the utilised particles are representative of particulate pollutants produced by combustion processes. The study evidences qualitatively potential adverse effects on waters which may arise from the association of these particles with common surfactants. (C) 2010 Elsevier B.V. All rights reserved.