In an oil spill, as the density of oil is less than water, oil will float on the surface. The natural agitation of water causes dispersion of oil that is spilled on the top layer of the water surface to go beneath into the water column. But this natural process takes a lot of time for the oil to be completely removed from the surface. To accelerate this natural phenomenon, oil dispersants are used.
Oil dispersants are chemical mixture of surface active substances added to colloid, to accelerate, and to improve the separation of particles and to prevent them from clumping with each other.
The main aim of oil dispersant is to suppress the oil spill effect by reducing the amount of oil coming ashore by water waves and by converting the spilled oil into small particles and droplets so that they can be dispersed beneath the water column.
Dew Concentrated dispersant are much easier to handle and deal with concentrated products. This dispersant consists of mixture of oxygenates like glycol and non aromatic hydrocarbon. They can be used after diluting but the latest concentrated dispersants can be used undiluted from ship as well as from aircrafts. The dosage for concentrated dispersants drastically reduces to 5-15 % of dispersant/oil quantity.
The quantity of dispersants used depend upon the following factors:
Advantage of using oil dispersant
Dispersants contain both surface-active agents (surfactants) and solvent systems. Each surfactant molecule has both a water-soluble 'head' group and an oil-soluble 'tail'. After contacting an oil slick on water, these molecules diffuse through the oil to the oil/water interface under the slick.
The surfactant acts to lower the oil/water interfacial tension, which means it lowers the energy needed to mix the oil into the water. This makes it easy for the oil to disperse into the water phase as discrete droplets. Each droplet has a molecular layer of surfactant molecules around it which helps to prevent the droplets from recombining and keeps them dispersed in the water phase. Through wind and wave action, the droplets are formed, dispersed throughout the water column and removed from the surface spill location. The droplets remain in suspension in the upper water column, stabilized by the surfactant molecules, thereby minimizing the adherence to fish, birds, boats and the shoreline. The tiny oil droplets are then consumed by natural bacteria in the water column removing the oil from the ecosystem.
Response to an oil spill at any stage has one important primary goal - to minimize the impact of the spill on the environment. Complete recovery of oil is rarely possible due to weather conditions or the size of the spill.
The challenge then becomes one of preventing oil from reaching the shoreline where damage to natural and commercial resources can be considerable.
All of Dew oil spill dispersants have passed stringent third part performance evaluations before being accepted for use. Furthermore, extensive environmental testing has to be performed on all oil spill dispersants to ensure that their impact on the aquatic environmental is minimal. For this reason, only those components that are known to have favorable environmental properties are used in oil spill dispersant products. Many of these components are readily used to stabilize food products, cosmetics or in pharmaceuticals.