Study of asphaltenes adsorption onto different minerals and clays.: Part 1.: Experimental adsorption with UV depletion detection

The adsorption of asphaltenes of five different origins from Gulf of Mexico, West Africa, North Sea and Brazil onto inorganic particles (kaolin, CaCO3, BaSO4, FeS, Fe3O4, TiO2 and SiO2 (hydrophilic and hydrophobic)) has been studied by means of the depletion method by assaying asphaltene concentration by UV-vis spectrophotometry (batch partioning method). The aim of this work is to investigate how adsorbed asphaltenes alter the particle properties. The saturation adsorbed amounts of the asphaltenes on minerals (0.26-3.78 mg/m(2)) were in the same order of magnitude as the adsorption of asphaltenes on metals. Langmuir (type 1) isotherms were observed. We found that adsorption depends more on particle type than on the origin of the asphaltenes. The adsorption was discussed from the point of quantity (maximum adsorbed amount, Gamma(max)) as well as of quality (affinity constant K). The potential interactions formed upon adsorption were analyzed. In our systems with excluded water we found polar interaction and surface precipitation as well as H-bond formation. We analyzed a correlation between adsorbed amount and elemental composition. We found a correlation between amount of nitrogen in asphaltene sample and its adsorbed amount on the particle. We did not find any correlation with particle wettability nor specific surface area. (C) 2007 Elsevier B.V. All rights reserved.