JOURNAL OF COLLOID AND INTERFACE SCIENCE 189, 242–253 (1997) ARTICLE NO. CS974807 Effects of Asphaltene Solvency on Stability

(‘‘wash water’’) is deliberately emulsified into the oil to The formation of stable and persistent emulsions and foams in contact hydrophilic materials, which then partition into the the production and re®ning of crude petroleum is a challenge aqueous droplets (10, 11). These desalter emulsions must which has de®ed broad and generic resolution for several decades. subsequently be broken down to recover the ‘‘clean’ ’ crude Rational and systematic approaches to demulsi®cation have been oil. However, a considerable proportion of these emulsionsslow to develop due to a lack of fundamental understanding of are very stable and lead to sludge generation (12). As thethe molecular origins of emulsion stabilization and the full range EPA continues to redefine specific petroleum-derived com-of factors which govern emulsion stability. Several studies have ponents which will be targeted as listed wastes, the needshown the importance of resins and asphaltenes, which have the to minimize the formation of petroleum emulsions and theability to organize and form rigid ®lms at the oil /water interface. We have developed a molecular model in which we propose that impetus to develop new methods for effective treatment of the integrity of these ®lms and thus their ability to stabilize water- them have become more acute. in-crude-oil emulsions are sensitive to a variety of crude solvency Despite years of research, there is a lack of a fundamental parameters, such as aromaticity, resin-to-asphaltene ratio, and po- understanding of the mechanisms governing the stability o