Sorbents are solid products used to collect the pollutant (by impregnation), in order to facilitate recovery.
There are two different categories of sorbents:
- Hydrophobic sorbents: used to recover apolar products (e.g. hydrocarbons). These sorbents can be use onland or in the water.
- Universal sorbents: used to recover both polar and apolar products (water, acid, bases, hydrocarbons...). These sorbents can only be used onland.
The use of oil-only sorbents to fix and agglomerate oil or certain other pollutants in the event of an incident is an efficient and commonly used technique to respond to small spills, on land, on calm water bodies (port or harbour) or clean-up sites (cleaning of banks or shores). Make-shift sorbents, such as straw or sawdust, can be used as a temporary measure.
On water, floating oil-only sorbents (low density) must be used, which, when in the presence of water and oil, are capable of fixing the oil (oleophilic property) rather than the water (hydrophobic property).
These products carry out both adsorption (on the surface of the product) and absorption (in the product itself).
They are available:
- in bulk, in the form of powder, fibres, shavings, fine particles...
- conditioned, in the form of mats, sheets, rolls, booms...
Very high density sorbents (density > water) which would cause the pollutant to sink should be avoided when operating on inland waters or at sea.