Synergistic effect of alkyl-O-glucoside and -cellobioside biosurfactants as effective emulsifiers of crude oil in water. A proposal for the transport of heavy crude oil by pipeline

Alkyl-O-glucoside and -cellobioside biosurfactants were synthesized with a long fatty chain (C8–C18) in order to prepare stable and low viscous oil-in-water (O/W) emulsions of a Mexican heavy crude oil. The resulting O/W emulsions, prepared with a single alkyl-O-glucoside or alkyl-O-cellobioside, were very unstable and broke out. Only the use of tetradecyl-O-cellobioside allowed the formation of a poor stable complex emulsion with the broader particle size distribution and more viscous than other emulsions. Nonetheless, we observed a synergistic effect when a biosurfactant mixture was used and the resulting emulsions were stable for several days while water separation occurred constantly within 40 days in static conditions. The mixture of biosurfactants with a pC20 value higher than 4.0 and a CMC/C20 ratio higher than 1.0 favored the formation of a less viscous, narrow particle size distribution and thermal stable O/W emulsion. This feature is remarkable important when we look for the pipeline transportation of heavy and extra-heavy crude oils as O/W emulsions. In this work, we present the characterization of biosurfactants as well as the formulation and properties of O/W emulsions of a Mexican heavy crude oil.