title: Investigation of the electrokinetic properties of paraffin suspension. 2. In cationic and anionic surfactant solutions.
abstract: Electrical phenomena at nonionogenic hydrophobic surfaces (solid or liquid) in water, electrolyte, and/or surfactant solutions still attract research. In part 1 of this paper we described the electrokinetic behavior of paraffin wax suspension in water and electrolyte solutions (NaCl or LaCl3). On the basis of the latest data of water structure near hydrophobic surfaces it was concluded that immobilized water dipoles at the interface can play an essential role in the zeta potential formation. In this paper were investigated the zeta potentials of paraffin wax in cationic surfactants cetyltrimethylammonium bromide, C16H33(CH3)3NBr, and octadecyltrimethylammonium chloride, C18H37(CH3)3NCl, and anionic surfactant sodium dodecyl sulfate, C12H25SO4Na. Also changes in wettability of the paraffin surface due to the surfactant's adsorption were studied via wetting contact angle measurements and calculation of the surface free energy. It was concluded that at a low surfactant concentration (10(-6) M) the water dipole structure still contributes to the zeta potential, but at a higher one the zeta potential is determined by the surfactant molecules' adsorption. A special role of OH- ions is also clearly seen. Moreover, a functional relationship was found between the surface free energy of the surfactant-covered paraffin surface and the zeta potential.
authors.affiliation: Department of Physical Chemistry-Interfacial Phenomena, Faculty of Chemistry, Maria Curie-Sklodowska University, 20031 Lublin, Poland. emil@hermes.umcs.lublin.pl
authors.forename: Emil
authors.initials: E
authors.lastname: Chibowski
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Wiacek
authors.forename: Lucyna
authors.initials: L
authors.lastname: Holysz
authors.forename: Konrad
authors.initials: K
authors.lastname: Terpilowski
mesh_terms: D000327:Adsorption; D000838:Anions / Q000737:chemistry; D002412:Cations / Q000737:chemistry; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry*; D004563:Electrochemistry; D007700:Kinetics; D010232:Paraffin / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*; D013997:Time Factors
chemical_list: D000838:Anions; D002412:Cations; D002593:Cetrimonium Compounds; D000644:Quaternary Ammonium Compounds; D012996:Solutions; D013501:Surface-Active Agents; C026584:dioctadecyltrimethylammonium; D012967:Sodium Dodecyl Sulfate; D010232:Paraffin; D000077286:Cetrimonium