Loose fiber adsorbent

Details Loose fiber adsorbent Loose fiber adsorbent

2001-06-06

2003-10-14

Cole, Elizabeth M. (Department: 1771)

Stock material or miscellaneous articles

Sheet including cover or casing

Noninterengaged fibered material encased

C428S076000, C428S212000, C428S220000, C442S327000, C442S414000

Reexamination Certificate

active

06632501

ABSTRACT:

FIELD OF THE INVENTION
The present invention is generally directed to a delustered fiber sorbent and a method of using the delustered fiber sorbent in the removal of hydrocarbon products from a contaminated material, and more specifically, to the removal of hydrocarbon products contaminating the surface of an aqueous medium, by employing a wadded mass of delustered hydrophobic and lipophilic fibers that are placed in contact with the contaminated surface so as to sorb the hydrocarbon products.
BACKGROUND OF THE INVENTION
The widespread use of petroleum products is accompanied by the almost statistical certainty that accidents involving the release of petroleum products into the environment will occur. In recognition of the deleterious effects such spills can have on the environment, many governmental agencies have drafted regulations mandating that spill response equipment, including sorbent material, be readily available to contain and collect the spilled material, to minimize the deleterious environmental effects of the petroleum products.
Due to increasing globalization, many nations are involved in transporting extremely large volumes of raw petroleum and petroleum products in tanker ships via waterways, such as lakes, rivers, and, oceans and in tanker vehicles or railcars that travel adjacent to waterways. Accidents involving large volumes of petroleum, such as the Exxon Valdez incident in Alaska, have generated tremendous concern among the public. In response to such incidents, various governmental agencies have adopted strict spill response regulations to prevent, or at least minimize, the damage from a future large scale spill on waterways. Such regulations often provide for the creation of spill response teams that are required to stockpile large quantities of sorbent material at locations that are associated with high traffic of large volumes of petroleum products. In recognition of the need for sufficient quantities of sorbent material to be readily available at many different locations, it would be desirable to provide an efficient, inexpensive, and lightweight sorbent product that can be used to remove petroleum and other hydrocarbon products from contaminated surfaces, including the surface of a body of water.
The prior art includes many different types of sorbent products. Sorbents work either by absorption, adsorption, or both. Absorption is a process in which a material is taken in through pores or interstices of another material, while adsorption is a process in which a material is accumulated on the surface of a solid or liquid. In general, sorbents that function via both absorption and adsorption tend to be more effective in enabling a petroleum or other hydrocarbon spilled on a surface to be collected and removed. It would therefore be desirable to provide a sorbent that is sufficiently economical and environmentally friendly to be used on the surface of a body of water, and which both adsorbs and absorbs petroleum and other hydrocarbon products.
The prior art recognizes that an effective sorbent material should have a high affinity for sorbing the target material to be collected and removed, and that the sorbent should preferably sorb a relatively large amount of the target material per unit weight of the sorbent. Effective sorbents tend to have a relatively great surface area, so as to encourage contact of the sorbent with the target material. With respect to sorbents employed to recover hydrocarbons from the surface of a body of water, a low specific gravity ensures that the sorbent will float on the water surface, both before and after hydrocarbons have been sorbed.
U.S. Pat. No. 5,304,311 discloses an elastomeric ethylene/alpha-olefin copolymer, optionally copolymerized with a diene, that can be applied in a granular subdivided form. After absorbing the hydrocarbon product, the sorbent forms a jelly-like, homogeneous mass, which can then be removed by conventional mechanical means. The jelly-like mass is cohesive, and modest wave action will not disperse the sorbent beyond a desired area of treatment. While effective, such a material requires a finite contact period to transition from the granular state to the jelly-like mass. Sorbents such as that disclosed in the above-referenced patent are often referred to as solidifiers, as they change oil from a liquid to a solid. Unlike sorbents, solidifiers do not release solidified oils under pressure, ensuring that the “dripping-sponge” effect is eliminated, which in some situations may be desirable. However, there are many instances in which it may be desirable to recover and recycle any petroleum product that has been picked up by a sorbent. A French study of oil solidifying agents concluded that the following problems are associated with solidifiers: (1) the reaction of cross-linkers (in the solidifier) with portions of oil that are in direct contact results in non-uniform solidification; (2) the non-selective nature of cross-linkers that will solidify anything that contains hydrocarbons, including weeds and other organic matters; (3) mechanical difficulty in removing a solidified spill, since it cannot be pumped; and, (4) the large amount of solidifier that is required to cross-link and solidify an oil spill. Finally, due primarily to the cost of the ingredients, such as the cross-linkers required to facilitate the solidifying reaction, solidifiers such as that disclosed in the above-referenced patent tend to be somewhat expensive. It would be desirable to provide a more rapidly acting sorbent material, which is less costly to produce, requires a relatively small volume of sorbent to be employed, and which can be processed to recover sorbed hydrocarbons if desired.
In addition to granular solidifying sorbents, the prior art also discloses the use of polymeric fibers and expanded polymeric foams to sorb petroleum products. U.S. Pat. No. 5,407,575 describes a relatively small two-part sorbent pad having a flat, chemically treated polyethylene foam inner core completely surrounded by a flexible, durable, chemically treated polypropylene fabric cover. The sorbent pad is intended to float on top of petroleum covered water and to soak up the petroleum or oil and hold it within the inner core until it can be removed by squeezing the sorbent pad between rollers, thereby recovering the oil for storage in a container. The sorbent pad can then be returned to the water to pick up more petroleum. The sorbent pad is chemically treated to increase the pad's ability to attract and hold oil by both adsorption and absorption and to further increase the pad's ability to repel water. This treatment necessitates extra processing in the manufacture of the sorbent, thereby increasing its cost. While the sorbent pad is useful, it would be desirable to provide a lower cost sorbent that are not in a pad configuration and thus can be carried or stored in large quantities as needed, in order to be able to treat massive oil spills, such as those associated with an oil tanker running aground and breaking apart.
In addition to employing polymeric granules and foams, the prior art also discloses using polymeric fibers as a petroleum sorbent. Many patents disclose various filters for either cleaning oil, or removing oil from water, which include polymeric fibers. Fibers that have little cotton or cellulose content are hydrophobic, and have a high affinity for petroleum. Examples of patents that disclose the use of polymeric fibers in a filter include U.S. Pat. No. 4,329,226, which discloses a filter apparatus for reconditioning oil and uses cotton fibers, polyester fibers, and wood (specifically aspen) fibers to filter dirty oil. U.S. Pat. No. 4,707,269 describes a non-woven hydrophobic fabric used to separate oil and water mixtures, and U.S. Pat. No. 5,855,784 describes a sheet filter formed of thermally bonded polymer fibers. U.S. Pat. No. 5,993,675 describes a fuel filter that includes polymeric micro-fibers to remove water from a hydrocarbon fuel.
Regulatory and governmental agencies are increasingly focusing on the use o

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