The team behind the current proposal has recently developed a dispersant using commercially available food-grade surfactants and has shown that it is efficient at emulsifying and dispersing crude oil into sea water. Initial work was funded by GoMRI via the Consortium for the Molecular Engineering of Dispersant Systems (C-MEDS), which was headed by a member of the current team, viz. John (Tulane). The current proposal seeks to build on this initial discovery. The goal is to engineer a new class of dispersants that combine environmental safety and high efficiency. By avoiding the synthetic components in current dispersants that are of questionable toxicity, and replacing them with food-grade components, new dispersants will be created that are nontoxic and safe for use in aquatic environments. At the same time, through an improved understanding of the fundamentals of dispersion, high dispersion efficiencies will be achieved that are comparable or higher than with current dispersants i.e., the Corexits.
This proposal is entirely focused on GoMRI Theme 4 (Technology developments for improved response, mitigation, detection, characterization, and remediation associated with oil spills and gas releases.) The use of food-grade dispersants will enable a safer and more environment-friendly approach to the mitigation of crude oil spills, which will help avert issues of public concern regarding dispersant toxicity. Molecular-level insights into dispersant action via innovative experiments will reveal ways to enhance the efficiency of dispersion and also allow for dispersants to be optimized for a variety of complex conditions (such as dispersion of highly viscous or weathered oils).
The project will involve the following five approaches: (1) Optimizing Food-Grade Surfactant Mixtures; (2) Optimizing Solvents and the Overall Dispersant; (3) Optimize Dispersants for Different Conditions (Oil, Water, Temperature); (4) Pilot-Scale Testing; and (5) Biodegradation and Toxicity Testing. In Approach 1, mixtures of food-grade surfactants, specifically mixtures of soy lecithin with nonionic surfactants from the Tween family, will be studied. To guide these studies, the oil/water interfacial tension will be monitored in the presence of these mixtures since it has been shown to correlate with dispersant effectiveness. In Approach 2, the focus will be on the solvent(s) used to solubilize the surfactants, which have been found to significantly impact the dispersion efficiency. An underlying theme here will be to contrast the mechanism for dispersion with that for emulsification. The PIs hypothesize that efficient dispersion is connected to the micellar nanostructure present in the dispersant and in dispersant/oil mixtures. This hypothesis will be critically evaluated via structural characterization at the nanoscale. If proven correct, it could indicate how dispersants could function even with limited extents of shear (i.e., minimal wave action on the open seas). In Approach 3, the insights from (1) and (2) will be applied to guide dispersant design for more difficult cases, such as the dispersion of highly viscous oils, dispersion into fresh or brackish water, and dispersion under cold temperatures.
The concept of food-grade dispersants is one of the truly promising ideas to come out of the work done under C-MEDS. This project seeks to translate the inherent idea into a practical and viable technology. Towards this end, pilot-scale testing of optimized food-grade dispersants (Approach 4) will be conducted using the indoor wave tanks at S. L. Ross Environmental Research. In addition, initial tests on bacterial biodegradation in the presence of food-grade dispersants will be studied (Approach 5). The toxicity of these dispersants to aquatic species will also be studied using commercial assays, and further aspects concerning toxicity and biological effects will be investigated together with collaborators. The team's research efforts will also support outreach and education efforts, particularly in Southeastern Louisiana, as well as to develop web content for GoMRI use
Project Research Overview (2016):
An overview of the proposed research activities from the GoMRI 2016 Meeting in Tampa.
Direct link to the Research Overview presentation.