Upon consideration of dispersant-related research, both before and after the Macondo Well oil release, it can be divided into two general categories: (1) the fundamentals of how dispersants work and the effects that may result from their use (e.g., physicochemical and transport characteristics of drops, bubbles, hydrates, surfactants), and (2) an applied focus that has emphasized the design of new dispersants or an enhancement of the performance of those products that are currently available.
While there is an extensive amount of data relating to dispersants, a main focus has been on the demonstration of their effectiveness in bench tests and examination of the toxicity of dispersants and dispersed oil. As a result, there is a need for an enhanced understanding of dispersant and dispersed oil thermodynamics and their fate and transport, with a goal to translate the science and engineering to the development of new, effective dispersant systems. The focus of the work to be discussed addresses the following areas:
Formation of small oil droplets: Widely dispersed stable oil droplets in the water column are easily accessible to microbes and therefore highly susceptible to degradation. It is important therefore, to understand the fundamental mechanisms of oil breakup and colloidal stabilization in order to develop new and effective dispersants.
Dispersant-related processes under deep sea conditions: Current dispersants have been developed for surface spills. The efficacy of such formulations when applied at the high pressures and low temperatures representative of deep ocean release has not been systematically studied. Because of concomitant gas release at the discharge point, and the pressures involved, the liquid droplet is essentially a gas-expanded liquid which could behave quite differently when treated with dispersant components depending upon how they partition at the phase interfaces, i.e., gas/water, gas/oil, oil/water.
Fluid mechanics of stabilized oil droplets: Droplet transport, as influenced by all thermodynamic variables of relevance under deep sea conditions, is being studied.
Droplet interactions with solid particulates: A better understanding of these processes, either in marine sediments or in the water column, will help predict the environmental fate of the droplets.
Development of alternative dispersants: Based on the knowledge gained with respect to the fundamentals, a key goal is the systematic translation of that understanding to the development of new and improved materials.
This paper summarizes recent work of a collaborative research effort involving investigators from 22 universities, with particular emphasis on increasing the understanding of the science and engineering of oil spill dispersants.