(590f) Eco-Friendly Sacrificial Amphiphiles As Chemical Herders for Oil Spill Remediaion

Currently, the two principal principal methods for responding to a maritime oil spill are the use of floating barrier booms to encircle and contract the spill, so that it may be removed by mechanical skimming or in-situ burning, and the aerial spraying of surfactants onto the spill to cause the oil slick to emulsify into small droplets that are carried away from the site or are broken down by microbes. Taken together they are an inadequate toobox: Booms are difficult to deploy, and dispersants do not really remove the oil from the marine biota, and the effect of currently utilized dispersants on marine life is under dispute.

The object of this proposal is to develop eco-friendly chemical herders for removing maritime oil spills. In this method, surfactant is aerially sprayed around the spill, to lower the large surface tension of the air/sea surface uncontaminated by the oil. The reduction in the surface tension causes the floating oil layer to retract and thicken to the point where it can be ignited, and the spill burned away. The most effective surfactant herders that have emerged from laboratory and field testing are silioxane polymers, which do not easily or rapidly degrade in the marine environment. The overall goal is to develop a new class of eco-friendly herders which are based on using a hydrophobic molecule found in abundance in the marine biota, phytol, as the surfactant tail. Effective surfactant herders are made by covalently attaching phytol to cationic and nonionic polar groups. The attachment is through an ester linkage which is located near the double bond of the phytol, allowing the polar groups to be hydrolyzed on adsorption of the surfactant to the air/sea interface to regenerate the phytol. Phytol-derivatized herders can penetrate into the biofilms which form on the sea surface, so that the air/sea tension can be effectively lowered on adsorption, and the sacrificial nature of the polar attachment, with regeneration of phytol, allows long-lasting herder action as the phytol remains on the surface.

We report results on two molecules derivitized with pyridinium and imidazolium cationic groups. In small pan scale experiments, these herders retracted oil slicks by up to ~500%, 700% and 2500% at 5 ^oC, 20 ^oC and 35 ^oC respectively, during the first 10 minutes of experiment, which is equivalent to the current best chemical herders in practice. We also demonstrate that the hydrophobic group of the phytol molecule, with single methylene group branches, which interlock with each other, forming a stable Langmuir monolayer with low tension and sustained herding action.