Hydrophilic-Lipophilic-Difference (HLD) Guided Formulation of Oil Spill Dispersants with Biobased Surfactants

Abstract The large-scale use of dispersants during the BP Horizon spill revealed various risks associated with these formulations, particularly the use of volatile organic compound (VOC) solvents linked to respiratory illnesses, and the poor biodegradability of surfactants. Previous attempts at solving these issues involved formulations of lecithin and polyethylene glycol ester of sorbitan monooleate (Tween ® 80) that still required the use of a volatile solvent, ethanol. In this work, the Hydrophilic-Lipophilic Difference (HLD) framework was used to develop a lecithin formulation containing food-grade lipophilic (Glycerol MonoOleate – GMO- and sorbitan monooleate – Span ® 80) and hydrophilic (polyglycerol caprylate) linkers in combination with a nonvolatile and mineral oil solvent with food additive status. The HLD parameters for lecithin, linkers, and oils were used to determine the lecithin-linker formulas that yielded HLD ∼0 (the surfactant phase inversion point), reaching interfacial tensions of 10 −2 mN/m, and high emulsification effectiveness with diluted bitumen. This effectiveness was close to that obtained with a simulated dispersant, and superior to the lecithin-Tween ® 80-ethanol formula. The lecithin-linker system produced 4–11 μm emulsified drops, sufficiently small to enhance the biodegradability of the dispersion.