Contraction and confinement of oil slicks on water, including water where ice is present, using non-ionic surfactants

Abstract

Methods for reducing the size of an oil slick on a water surface or on a water surface when ice is present are described. Spreading of oil can be reversed by reducing the surface tension of the seawater, for example, by using a low concentration of at least one water-soluble surfactant, such as a non-ionic surfactant. A controlled amount of the surfactant or surfactant mixture may be discharged over time at the inner-wall of a spill control boom surrounding the oil spill, or within the vicinity of the oil spill in the absence of control booms using a soaker hose or a floating polyethylene or polypropylene hose impregnated with surfactant, whereby the confinement and contraction of the oil slick is maintained by compensating for dissolved surfactant and surfactant moving away from the oil slick. Water-soluble surfactants are typically solids or gels at low temperatures when no organic co-solvent is added to the surfactant. The solid or gel form is advantageous for generating slow, but continuous release of surfactant, and thus there is no need for an organic co-solvent. This is not the situation for oil-soluble surfactants, which require an organic co-solvent to be successfully applied at low temperatures. Mixing oil-soluble surfactants with water-soluble surfactants may overcome the problem of dispersing oil-soluble surfactant without an organic co-solvent at low temperatures.