Liquid purification or separation – Processes – Chemical treatment
Reexamination Certificate
1999-03-04
2001-07-17
Metzmaier, Daniel S. (Department: 1712)
Liquid purification or separation
Processes
Chemical treatment
C210S925000, C516S058000, C516S065000, C516S069000, C510S365000
Reexamination Certificate
active
06261463
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates in general to dispersing agents for dispersing oil and other petrochemicals from the surface of bodies of water, and in particular to a new and useful dispersant which is water-based and avoids the use of petroleum distillates, the major solvent in all currently US EPA approved oil spill dispersants.
There are two basic mechanisms for dealing with an oil spill on a body of water, such as crude oil from a tanker at sea. One is to try and recover the oil and the other is to disperse the oil. Recovery has proven to be extremely ineffective in that only a small portion of the oil is actually recovered, allowing the rest to reek havoc on nearby shorelines and wild life.
Currently, the United States Environmental Protection Agency (EPA) permits the use of only four commercially available dispersants to disperse oil spills. Two of them are known by the trade name COREXIT and are available from Nalco/Exxon Energy Chemicals, LP. of Sugar Land, Tex. COREXIT 9597 and the more recent COREXIT 9500 compositions both contain a large percentage of petroleum distillates. The other two permitted dispersants are known by the trademarks NEOS AB 3000 for a hydrocarbon solvent based dispersant available from NEOS Company Limited of Kobe, Japan, and MARE CLEAN 200, also based on hydrocarbon solvents and available from Taiho Industries Co., Ltd. of Tokyo, Japan.
The use of mineral spirits and other hydrocarbon based dispersants is counterproductive in that it adds to the loading of the ocean with compounds of the same petrochemical class as the spill itself.
The dispersing effect of a dispersant must also be balanced against its toxicity to fish and other wild life.
U.S. Patent 5,399,350 to Potter, assigned to Nurture, Inc., discloses a proteinaceous oil spill dispersant. Reference is made in this patent to two water-based dispersants, one identified by the trademark ATLANT'OL AT-7, available from Aspra, Inc. and the other known by the trademark OMNI-CLEAN OSD, available from Delta Omega Technologies. Delta Omega Technologies is also the assignee of U.S. Pat. No. 5,308,550 for a cleaning and wetting agent and solvent.
U.S. government regulations that dictate the characteristics of an acceptable dispersant with regard to effectiveness and toxicity, are found in 40 CFR § 300.900 and following sections. Comparative tests following the protocol of these regulations are appear later in this disclosure in a section entitled TESTING OF DISPERSANT EFFICIENCY.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a surfactant-based and water-based dispersant which includes a unique combination of both predominately oil-soluble and predominately water-soluble surfactants with a co-solvent and, in preferred embodiments, a significant proportion of water.
The dispersant of the invention has been found to be extremely effective in dispersing oils, including South Louisiana Crude (SLC) and Prudhoe Bay Crude (PBC) as proven by laboratory tests that follow the protocols of 40 CFR § 300. The dispersant of the invention also has low toxicity as proven by clinical toxicity tests conducted according to the protocols of 40 CFR § 300. Both tests demonstrate superior performance of the invention over the four EPA approved dispersants mentioned above.
A further object of the present invention is to provide a dispersant which contains from about zero to about 50 percent by weight water, from about 35 to about 85 percent by weight predominately oil-soluble surfactant, about 8 to about 32 percent by weight predominately water-soluble surfactant, and about 4 to about 16 percent by weight co-solvent.
For the purpose of this disclosure, the term predominately oil-soluble surfactant is used to mean a surfactant selected to have at least some water-soluble characteristics and, in the case of a non-ionic surfactant, to have an HLB or Hydrophilic and Lipophilic Balance, which averages about 10 to about 18. The predominately oil-soluble surfactant of the preferred embodiment of the invention is made up of one or more surfactants, and preferably three different non-ionic surfactants that each contribute their own unique combination of oil solubility and water solubility to the dispersant, to initially combine with the oil and form an emulsifiable combination.
The term predominately water-soluble surfactant is used to mean a combination of one or more surfactants which are preferably anionic and which solubilize the combination of oil-soluble surfactant and oil, into the body of water suffering from the oil spill.
The term petrochemical spill or oil spill is used here broadly to include any petrochemical spill; e.g. a spill of crude oil, processed oil, fuel oil, gasoline and other hydrocarbon containing products and materials.
The co-solvent of the invention acts as a coupling agent to help further draw the oil-plus-surfactant mixture into emulsion with the water. The term is meant to include the examples given in this disclosure and any other chemical which has a coupling effect as explained here.
The water component of the composition, where present, helps advance the interaction between the predominately oil-soluble surfactant and the predominately water-soluble surfactant as well as the co-solvent. In addition, water helps reduce the viscosity of the dispersant composition of the invention to allow the composition to be pumped under pressure. This is important in that dispersants for use in dispersing an oil spill are generally applied by high pressure pumping, often from helicopters or cargo planes flying over the affected area. The preferred embodiment of the dispersant of the present invention has a viscosity of about 140 cP (centipoise) with a preferred range for viscosity being about 75 to about 200 cP.
Another object of the invention is to provide a method for dispersing a petrochemical spill on a body of water, comprising providing the dispersant of the invention and supplying an effective amount of the dispersant onto the body of water at the spill, for dispersing the spill by emulsifying at least some of the petrochemical into the body of water. This included spraying or pumping the dispersant into or onto the water near the spill, or into or onto the spill itself. Advantageously the dispersant is supplying to the petrochemical spill in an amount of about one part dispersant to about 5 to 100 parts petrochemical, and preferably in a ratio of about 1:10 (dispersant to petrochemical).
A still further object of the invention is to provide a petrochemical spill dispersant and method which is superior to existing, approved dispersants, in both effectiveness and non-toxicity.
Yet another object of the invention is to provide a petrochemical spill dispersant and method of using the same, the dispersant being water-based and being especially formulated from various select surfactant types and combinations so as to orchestrate a complex and effective interaction that includes interfacial surface tension reduction, coupling and emulsification of the dispersant ingredients among themselves and with the petrochemical and water from the body of water.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure.
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patent: 4469603 (1984-09-01), Lepain et al.
patent: 4764285 (1988-08-01), Robbins et al.
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patent: 5385675 (1995-01-01), Vroman et al.
patent: 5618468 (1997-04-01), Canevari et al.
patent: 5728320 (1998-03-01), Fiocco et al.
Rosen, Surfactants And Interfacial Phenomena, (John Wiley & Sons, NY, NY, copyright 1978) pp. 242-245, May 1983.
Bergman, Jr. Robert E.
Jacob Savarimuthu M.
Metzmaier Daniel S.
Notaro & Michalos P.C.
U.S. Polychemical Marine Corp.
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