Functional surfactants from natural materials have the advantage of being biodegradable and can be obtained through sustainable agriculture. We have studied the properties of functional natural surfactants obtained from the Opuntia ficus indica cactus as dispersants of crude oil droplets in water (O/W emulsions), in both fresh and seawater. We studied the effect of oil concentration and surfactant concentration on droplet size and stability, as well as on the critical micelle concentration. Since emulsification is caused by the stirring of an oil/surfactant/water system, the dynamic equilibrium of the droplets inducing their rupture and coalescence depends on the formulation and composition variables, mixing characteristics and preparation conditions. Three extracts of this cactus plant have been studied for their effectiveness as dispersants and have been compared with those from Corexit 9500, which is a commercial dispersant for crude oil. We found that these natural surfactants effectively dissolve heavy and light crude oil from the air-water interface of a water column for rapid biodegradation. We determined that the amount of natural surfactants needed to obtain optimal dispersion stability is lower than that needed of Corexit. We also determined the droplet size and size distribution of the dispersed phase as a function of the dispersant to ratio depends on surfactant composition.  These characteristics are important to understand the effective use of natural dispersants and its intrinsic character to modify interfacial properties and to improve their dispersion efficiency. We expect the use of natural dispersants will have a positive environmental, economic, and societal impact in crude oil cleanup operations.

Fundamental properties of natural surfactants for effective oil/water dispersions

248th National Meeting (2014)

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