oil spill Dispersant info Chemical Man

An oil dispersant is a mixture of emulsifiers and solvents that helps break oil into small droplets following an oil spill. Small droplets are easier to disperse throughout a water volume, and small droplets may be more readily biodegraded by microbes. Dispersant use involves a trade-off between exposing coastal life to surface oil and exposing aquatic life to dispersed oil. While submerging the oil with dispersant may lessen exposure to marine life on the surface, it increases exposure for animals dwelling underwater, who may be harmed by toxicity of both dispersed oil and dispersant. Although dispersant reduces the amount of oil that lands ashore, it may allow faster, deeper penetration of oil into coastal terrain, where it is not easily biodegraded.

Requirements

There are five requirements for surfactants to successfully disperse oil:

   Dispersant must be on the oil's surface in the proper concentration
    Dispersant must penetrate (mix with) the oil
    Surfactant molecules must orient at the oil-water interface (hydrophobic in oil and hydrophilic in water)
    Oil-water interfacial tension must be lowered (so the oil can be broken up).
    Energy must be applied to the mix (for example, by waves).

Degradation and toxicity

Both the degradation and the toxicity of dispersants depend on the chemicals chosen within the formulation. Compounds which interact too harshly with oil dispersants should be tested to ensure that they meet three criteria:

    
Methods of use

Oil Spill Response Boeing 727 displaying its dispersants delivery system at the 2016 Farnborough Airshow Dispersants can be delivered in aerosolized form by an aircraft or boat. Sufficient dispersant with droplets in the proper size are necessary; this can be achieved with an appropriate pumping rate. Droplets larger than 1,000 µm are preferred, to ensure they are not blown away by the wind. The ratio of dispersant to oil is typically 1:20.