New Absorbent for Oil Spills
An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially marine areas, due to human activity, and is a form of pollution. There are several possible methods to remove the oil from the environment. A new absorbent has been proposed which is a polyolefin-based petroleum superabsorbent called PETROGEL that not only absorbs floating oil, but allows for its recovery and subsequent refining. When applied to a spill, PETROGEL immediately begins to absorb oil (but not water), and within 10 minutes will increase its weight by more than 10 times. Within 12 hours, Chung (Penn State researcher) says, it can absorb 40 times its own weight in oil. "The resultant solid mass will continue to float on the surface," he says, "and can be scooped up from the water or shore."
Polyolefins are thermoplastics used in shrink wraps and other food packaging; they are inexpensive and widely produced. Chung estimates that the cost of commercially producing PETROGEL could be below $2 per pound, while the amount of oil recovered per pound of material—around 5 gallons—would be worth $12, based on a crude oil price of $80 a barrel. In addition, PETROGEL can be refined along with the oil it absorbs, avoiding the hazardous waste byproducts associated with disposal of other clean-up materials.
Cleanup and recovery from an oil spill is difficult and depends upon many factors, including the type of oil spilled, the temperature of the water (affecting evaporation and biodegradation), and the types of shorelines and beaches involved. These include controlled burning, bioremediation, dispersion, absorption, and skimming.
At the recent BP spill in the Gulf of Mexico, it was estimated by the Coast Guard that only about 10 percent of the BP’s oil was removed by mechanical recovery such as skimming. Dispersion and controlled burning were the more likely methods to be used there. So recovery of the oil was minimal. Even with skimming the oil recovered is usually considered as a waste product.
There have been other technologies reporting the absorption of the spilled oils with inorganic mineral products (i.e. clay, silica, zeolites, etc.) and organic vegetable products (straw, corn corb, peat moss, wood fiber, cotton fiber, etc.). Most of them show limited oil absorption capacity and also absorb water.
Several synthetic fibers, as used in pads and booms, have also been used; they absorb oil in their interstices by capillary action. Because the weak oil substrate interaction (adsorption mechanism), the fiber based absorbers exhibit many disadvantages, including failure to maintain oil of low viscosity and easy re-bleeding of the absorbed oil under a slight external force. There are also some patents disclosing the usage of synthetic resins, such as acrylic copolymers. However, they have the drawback of a long absorbing time, especially for aliphatic hydrocarbon components. As compared to the polyolefin absorbent, the other absorbents are inferior.
For further information see Petrogel.
Cleanup image via Penn State.