WO2001011126A1

WO2001011126A1 - Oil sorbent material

Info

Publication number: WO2001011126A1
Application number: PCT/US2000/001328
Authority: WO
Inventors: Wayne E. Shaw; Mark Trabbold; Kenneth D. Knapp
Original assignee: Certainteed Corporation
Priority date: 1999-08-05
Filing date: 2000-01-20
Publication date: 2001-02-15
Also published as: AU2511100A

Abstract

Fibrous oleophilic and hydrophobic sorbent materials that are useful for removing oil spills and similar discharges from waterways and land structures (16). In one embodiment, the fibrous materials (110) are loose-fill (i.e., unbound) fiber glass. In another embodiment, the fibrous materials (110) are loose cellulose fibers. According to both embodiments, the fibrous materials are coated with a light coating of a substance which renders the fibrous materials buoyant in water (112) and therefore easily retrievable when used to remove oil spills (114) from bodies of water. The coating substance consists essentially of silicone but may also include other constituents. The sorbent materials are easier to manufacture and use and have sorbency and buoyancy characteristics comparable or superior to fibrous oil sorbents heretofore known in the art.

Description

OIL SORBENT MATERIAL

FIELD OF THE INVENTION The present invention relates in general to sorbent materials and in particular to oleophilic materials suitable for absorbing and/or absorbing oils.

BACKGROUND OF THE INVENTION Accidental discharges of crude and refined oils, gasoline and the like, especially into waterways, have the potential to wreak considerable harm on the ecosystem. If a spill is large, localized populations of mammals, marine life and other animals and plants may be threatened. Many of the known techniques for removing or mitigating such spills may be costly and time consuming. Moreover, their effectiveness may be less than desirable and they may produce ancillary problems. For instance, igniting oil slicks on water or land may be dangerous to surrounding persons or property as well as animal and plant life. Oil dispersants and detergents often produce residual by-products which themselves may be harmful. Because of these shortcomings, sorbent materials often represent an attractive alternative by which to clean up oil spills and the like. As used herein, terms such as "sorb", "sorbent" and the like shall be construed to encompass materials which "absorb" and/or "adsorb" liquids. However, in certain instances where appropriate for clarity of expression, the present text specifically indicates whether "absorbency" and/or "adsorbency" phenomena are present or whether one or the other predominates.

Sorbent materials which have shown potential as effective means for treating aquatic and non-aquatic oil slicks include mineral and glass fibers and particles. U.S. Patent No. 5,215,407, for example, proposes the use of shredded or unshredded fiber glass-based blowing wool compositions to treat oil spills located on bodies of water or on land. That patent asserts that an advantage to using such materials on water is that, if the proper fiber glass insulation material is employed, the fiber glass displays an affinity for sorbing oil rather than water. Because of the inorganic nature of fiber glass blowing insulation materials, such materials "adsorb" rather than "absorb" liquids. The fiber glass compositions disclosed in U.S. Patent No. 5,215,407 consist essentially of fiber glass blowing insulation with the possible inclusion of cork and/or styrofoam to provide absorption capability and compression resistance. The fiber glass may also be sprayed with a mist of an antifreeze and water solution to reduce static and dust given off as the particles are sprayed onto an oil spill.

U.S. Patent No. 5,215,407 mentions several possible commercially available materials which are suitable for use as the basis of the fiber glass blowing wool composition particles disclosed therein: InsulSafe III® fiber glass blowing insulation made by CertainTeed Corporation of Valley Forge, PA, Rich-R® fiber glass blowing insulation made by Johns Manville Corporation of Denver, CO and Thermacube® fiber glass blowing insulation made by Owens Corning of Toledo, OH. For aquatic oil spill applications, the patent recommends using InsulSafe III® fiber glass blowing insulation allegedly because it does not tend to absorb water. In relative terms, versus Rich-R® and Thermacube® fiber glass blowing insulations, InsulSafe III® fiber glass blowing insulation may take on less water. However, it is not a truly hydrophobic material.

InsulSafe III® fiber glass blowing insulation is an unbonded, white, virgin fiber, loose-fill fiber glass insulation applied by pneumatic means for the purposes of insulating attics, wall spaces and other areas of buildings. To facilitate placement and enhance performance of the insulation in its dedicated building insulation applications, the glass fibers are coated with several materials tailored to achieve certain beneficial results or properties. Among these are silicone emulsion which functions as a lubricant and quaternary ammonium salts which function as an antistatic agent. The silicone is a protective coating on the glass (i.e., it keeps fibers from abrading against each other). Silicone enhances recovery during the process of blowing (i.e., returns loft to the fiber to yield a high R- value). It has been shown that InsulSafe III® fiber glass blowing insulation, as well as the Thermacube® fiber glass blowing insulation (which is acknowledged in U.S. Patent No. 5,215,407 to be even more water sorbent than InsulSafe III® fiber glass blowing insulation), rapidly sinks if used to treat an aquatic oil slick. Sunken oil spill treatment material may at times be difficult if not impossible to retrieve. This in turn may lead to ecological contamination of the marine environment in the vicinity of the sunken material.

U.S. Patent No. 5,078,890 describes a technique for treating an aquatic oil spill using particles of felts made of mineral wools (glass or rock wool). The mineral wools are bound by a hydrophobic formophenolic binding resin and are cured at elevated temperature. The felts are cut into particles of less than 4 cm and then compressed to reduce volume during storage and transport. At the time of application, the densified particles are decompressed and unbound and then sprayed onto an oil spill by a pneumatic stream, so that they regain their original density. Silicone or similar hydrophobic agents may be provided in addition to the binding resin at the time of manufacture of the felts in a proportion of approximately 0.5 to 3.0 weight percent of the glass fibers. The product described in the U.S. Patent No. 5,078,890 is marketed by Isover Saint-Gobain of Aubervilliers, France. It is oleophilic and hydrophobic and floats on water and thus is useful for its intended purposes. Nevertheless, its manufacturing processes and subsequent handling and deployment techniques are somewhat elaborate, as well as material, energy and cost intensive. Fiber glass has been proposed for use as a means for cleaning up or ameliorating accidental discharges of oil on land and water. U.S. Patent No. 5,078,890, as noted above, describes the use of commercially available loose-fill fiber glass insulation for such purposes. However, the coating substances applied to conventional blow wool fiber glass insulation, while useful additives when the fiber glass is employed for its designated purpose as building insulation, do not significantly offset the tendency of the fiber glass to sink when the insulation is employed in clean-up of aquatic oil spills. And, U.S. Patent No. 5,215,407 discloses a fiber glass based oil cleanup product which, although buoyant, is nevertheless somewhat cumbersome to manufacture and deploy.

FIG. 1 illustrates a mass of conventional loose-fill blow wool fiber glass 10 (density = 2.55 g/cm³) suspended above discrete quantities of water 12 (density = 1.0 g/cm³) and SAE 30 weight motor oil 14 (density = 0.95 g/cm³) disposed on a solid substrate 16 prior to contact of the fiber glass with the oil and water. FIG. 2 shows fiber glass 10 in contact with the substrate 16 and adsorbing the oil and water which are respectively symbolized by ovals 12 and 14. FIG. 2 reflects that conventional loose fill fiber glass 10 exhibits excellent wicking characteristics with respect to both water and oil and indiscriminately adsorbs both of these liquids. Indeed, water is adsorbed more quickly than oil due to its lower viscosity. FIG.3 shows a bundle or mass of conventional fiber glass 10 submerged in a volume of water 12 disposed within a vessel 18 shortly after placement of the fiber glass atop the surface of the water. Because of the excellent wicking properties of the fiber glass coupled with its approximately 2 1/2 times greater density than water, it quickly adsorbs its available capacity of water and sinks to the bottom of vessel 18.

FIG. 4 depicts a mass of CertainTeed InsulSafe III® fiber glass blow wool insulation 10 shortly after it has adsorbed a quantity of Brass River crude oil which was previously dispensed atop a quantity of water 12 in vessel 18. However, fiber glass 10 quickly and indiscriminately adsorbs both water and oil (ovals 12, 14). Once the water 12 and oil 14 penetrates and saturates the fiber matrix, the fiber glass rapidly sinks.

A desire exists, therefore, for a hydrophobic and oleophilic sorbent material which is useful in treating aquatic and non-aquatic oil-based pollutants. Preferably, the material should be highly buoyant when used in aquatic environments and comparatively inexpensive and easy to manufacture and use.

SUMMARY OF THE INVENTION The present invention is a sorbent material comprising loose fibers coated with a coating consisting essentially of silicone.

Another aspect of the invention is a method of making a sorbent material. A quantity of loose fibrous material is selected. The loose fibrous material is coated with a coating consisting essentially of silicone.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will become more readily apparent from the following description of preferred embodiments thereof shown, by way of example only, in the accompanying drawings wherein:

FIG. 1 is a view comparing the approximate densities of conventional loose- fill fiber glass blow wool, water and motor oil;

FIG. 2 is a view depicting the indiscriminate adsorptivity of conventional loose-fill fiber glass versus oil and water; FIG. 3 is a view of a quantity of conventional loose-fill fiber glass which has adsorbed water and then sunk in the water;

FIG. 4 is a view of a quantity of conventional loose-fill fiber glass which has indiscriminately adsorbed oil and water and then become sunk in water; and FIG. 5 is a view of a first preferred embodiment of a sorbent material according to the present invention selectively adsorbing oil in favor of water;

FIG. 6 is a view of a first preferred embodiment of a sorbent material according to the present invention which has selectively adsorbed oil and remains buoyant in water.

DETAILED DESCRIPTION OF THE INVENTION

In research and development culminating in the present invention, as described in greater detail below, it has been discovered that a coating consisting essentially of silicone should cause loose-fill fiber glass insulation to float when brought into contact with a body of water. However, InsulSafe III® fiber glass blowing insulation has been shown to sink rapidly when added to water. Although the reason for this is not fully understood, it may be that the quaternary ammonium salts antistatic agent somehow is responsible for substantially negating the buoyancy effect of the silicone.

The present invention provides fibrous oleophilic and hydrophobic sorbent materials and methods for making and using such materials. The sorbents are useful for removing oil spills and similar discharges from waterways and land structures. In one embodiment the fibrous materials comprise loose-fill (i.e., unhindered) fiber glass commonly known as "blow", "blown" or "blowing" wool, or fiber glass particulate. In another embodiment the fibrous materials comprise loose cellulose fibers. According to both embodiments, the fibrous materials are coated with a light coating of a substance which renders the fibrous materials buoyant in water and therefore easily retrievable when used to remove oil spills from bodies of water. The coating substance consists essentially of silicone but may also include other constituents, such as paraffin oil. The sorbent materials are easier to manufacture and use and have sorbency and buoyancy characteristics comparable or superior to fibrous oil sorbents heretofore known in the art.

FIG. 5 qualitatively reflects the adsorbency characteristics of loose-fill blow wool fiber glass 110 according to the present invention versus discrete quantities of water

112 and SAE 30 weight motor oil 114. Fiber glass 110 may be manufactured according to any process suitable for producing loose-fill fiber glass, e.g., centrifugation and gas stretching techniques. Such processes are well known to those skilled in the subject art. Hence they are not discussed in detail herein. Following formation of the fiber glass, however, and pursuant to an exemplary embodiment of the present invention, the fiber glass is desirably coated with about 0.05 to about 0.10 weight percent silicone in relation to fiber weight.

If the silicone content is substantially below about 0.05 weight % silicone, the fibers do not remain buoyant. However, there is no scientific limit to how much silicone may be used. Silicone has a specific gravity below 1.0 grams/cm³. Given its natural buoyancy, 100% added silicone would also work. In practice, however, high levels of silicone would be wasteful and costly. The preferred range is between 0.05% and 0.5% silicone.

The glass may be coated by the following exemplary process. As the glass fibers leave a rotary spinner (e.g., centrifugation fiberizing unit), they are immediately sprayed with the silicone emulsion. The silicone emulsion is pumped from a storage tank through a system of hoses into a 0.5" (1.27 cm) stainless steel tubing, which has been formed into a circular ring with a diameter of approximately 36" (0.9 m). Several spray nozzles may be located around this ring. The spray nozzles are pointed towards the center. When the fibers are formed, air pressure, introduced in the fiber forming processes, forces the fibers down and through this application ring. The newly formed fibers are coated with the silicone emulsion, as they pass through the ring at a very high rate of speed.

The exemplary product uses no binding agents (e.g., formo-phenolic), and provides a loose-fill hydrophobic, oleophilic product. Silicone is the sole hydrophobic constituent chemical. Silicone creates a product that is hydrophobic and that, when blown, enables the fiber to spring back after high compression. This product has numerous advantages over prior art products, such as the bound felt insulation with 0.5 to 3.0 % silicone described in U.S. Patent 5,078,890 referenced above.

It has been observed that a silicone coating promotes buoyancy of the fiber glass 110 while also imparting oleophilic and hydrophobic characteristics to the fiber glass. A presently preferred silicone is Dow Silicone 346 marketed by the Dow Chemical Company of Midland, MI. Since it is preferred that fiber glass 110 be pneumatically dispensed when used to treat large scale oil spills, fiber glass 110 may be optionally coated with 1.0% to 3.0% oil in an amount sufficient to function as a dust suppressant during dispensing of the fiber glass. The oil may be, for example, "PROREX 100™" oil marketed by the Mobil Corporation or "SUNPAR LW110™," marketed by the Sun Company. However, any oil or other substance suitable for suppressing dust which does not materially impact the oleophilic and hydrophobic benefits imparted by the silicone would be acceptable for the intended objectives of the present invention. A preferred composition includes 0.27 % silicone and not more than 1.8 % oil. As shown in FIG. 3, fiber glass 110 according to the invention preferentially absorbs oil 114 in favor of water 112.

An exemplary paraffin oil which may be added to prevent dust and irritation has a viscosity between about 18.7 and 22.0 cSt at 40 ° C, a minimum flash point of 380 °F, and a specific gravity of about 0.862 at 60 °F.

Simulated oil slicks were created to compare the relative buoyancy characteristics of conventional loose-fill fiber glass blow wool insulation and the silicone- coated, loose-fill fiber glass blow wool of the present invention. Each oil slick was prepared in the laboratory by adding 15.0 grams of Brass River crude oil to 400.00 grams of tap water held in separate vessels at room temperature. Then, 1.0 gram of shredded CertainTeed InsulSafe III® fiber glass blow wool insulation was placed in one vessel and 1.0 grams of silicone-coated, loose-fill fiber glass blow wool according to the instant invention was placed in the other vessel. Within approximately one minute each sample of fiber glass adsorbed substantially all of the oil. However, the CertainTeed InsulSafe III® fiber glass blow wool insulation sample sank rapidly whereas the sample of loose-fill fiber glass blow wool pursuant to the present invention, whose coating consists essentially of silicone, floated, for practical purposes, indefinitely. FIG. 6 shows a mass of silicone-coated, loose-fill fiber glass blow wool 110 in accordance with the present invention floating atop a volume of water 12 contained in a vessel 18. Fiber glass 110 adsorbs oil (ovals 14) to the substantial exclusion of water. In effect, when deployed in clean-up of aquatic oil spills, fiber glass 110 is readily and completely retrievable when saturated with oil. Consequently, any possibility that the oil- soaked fiber glass would sink and possibly become lost at the bottom of a body of water is effectively eliminated.

In research and development culminating in the present invention, it has been observed that, in addition to inorganic mineral fibers such as fiber glass blow wool, a coating consisting essentially of silicone enhances the sorbency of loose and otherwise untreated cellulosic fibrous materials as well. Untreated cellulosic fibers such as ground newspaper print, wood pulp and the like both adsorb and absorb liquid, whereas untreated fiber glass adsorbs liquid. However, like untreated fiber glass, untreated cellulosic fibers indiscriminately sorb water and oil. As a result, untreated cellulosic fibers, like untreated mineral fibers, tend to sink rapidly when used to clean up aquatic oil spills.

Pursuant to the present invention, it has been observed that when cellulosic fibers are treated with silicone which is the same as or similar in quality and quantity to that applied to fiber glass 110 discussed hereinabove, the coated cellulosic fibers selectively adsorb and absorb oil in favor of water. As a result, cellulosic fibers coated with silicone demonstrate markedly superior buoyancy versus untreated cellulosic fibers. Specifically, untreated cellulosic fibers tend to sink in a few minutes, whereas silicone-coated cellulosic fibers have been shown to adsorb and absorb oil and remain afloat for between about 30 to about 60 minutes.

According to either embodiment of the present invention, the silicone-coated fibrous materials provided for herein are efficient sorbents for oil. In particular, silicone- coated fiber glass 110 and cellulosic fibers have respectively demonstrated the capacity to sorb over 20 times and 15 times their weight of SAE 30 weight motor oil.

Although the invention has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claim should be construed broadly, to include other variants and embodiments of the invention which may be made by those skilled in the art without departing from the scope and range of equivalents of the invention.

Claims

CLAIMS 1. A sorbent material comprising loose fibers coated with a coating consisting essentially of silicone.

2. The sorbent material of claim 1, wherein said loose fibers comprise fiber glass.

3. The sorbent material of claim 1, wherein said loose fibers comprise cellulosic fibers.

4. The sorbent material of claim 1, wherein said coating is provided in an amount of about 0.05 to about 1.0 weight percent silicone in relation to fiber weight.

5. The sorbent material of claim 4, wherein said coating is provided in an amount of about 0.05 to about 0.5 weight percent silicone in relation to fiber weight.

6. The sorbent material of claim 1, wherein said coating further includes oil in an amount sufficient to function as a dust suppressant during dispensing of the sorbent material upon a substance to be treated by the sorbent material.

7. The sorbent material of claim 6, wherein the coating includes 1.0% to 3.0% oil.

8. A method of making a sorbent material comprising the steps of: selecting a quantity of loose fibrous material; and coating said loose fibrous material with a coating consisting essentially of silicone.

9. The method of claim 8, wherein said loose fibrous material comprises fiber glass.

10. The method of claim 8, wherein said loose fibrous material comprises cellulosic fibers.

11. The method of claim 8, wherein said coating is provided in amount of about 0.05 to about 1.0 weight percent silicone in relation to fiber weight.

12. The method of claim 11 , wherein said coating is provided in amount of about 0.05 to about 0.5 weight percent silicone in relation to fiber weight.

13. The method of claim 8 wherein said coating further includes oil in an amount sufficient to function as a dust suppressant during dispensing of the sorbent material upon a substance to be treated by the sorbent material.