Hydraulic and earth engineering – Earth treatment or control – Chemical
Reexamination Certificate
1999-07-01
2001-06-26
Suchfield, George (Department: 3672)
Hydraulic and earth engineering
Earth treatment or control
Chemical
C166S066500, C166S292000, C405S266000, C405S270000
Reexamination Certificate
active
06250848
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for guidance, containment, treatment and imaging of contaminants and other substances in a subsurface environment, utilizing ferrofluids.
Ferrofluids are stable colloidal suspensions of ferromagnetic particles in carrier liquids. The solid, single-domain magnetite particles have an average diameter of 10 nm and are covered with a molecular layer of dispersant. Brownian motion keeps the particles suspended, while the dispersant coating prevents the particles from agglomerating. The stability of ferrofluids means that neither external magnetic fields nor gravity can significantly change the concentration of the magnetic particles in the carrier liquid. Consequently, ferrofluids move as a homogeneous pseudo-single-phase fluid when flowing under the influence of a magnetic field. This attribute is responsible for the unique property of ferrofluids enabling them to be manipulated through the application of external magnetic fields in virtually any fashion defying gravitational or viscous forces. Therefore, ferrofluids can be made to flow in a desired direction and move precisely without any physical contact. Additionally, ferrofluids cast a strong magnetic signature through their distinct magnetic and electrical resistance properties.
2. The Relevant Art
Due to their ability to be held in place by magnetic fields, ferrofluids currently find application in a variety of products, including (a) hermetic seal pumps, where ferrofluids are used to eliminate leakage along rotating shafts and joints, (b) rotating vacuum seals used in semiconductor processing and environmentally controlled chambers, and (c) high-fidelity audio speakers and precision bearings. The biomedical field has exploited ferrofluids for use in (a) tracing blood flow in non-invasive circulatory measurements, and (b) transporting therapeutic agents incorporated onto the magnetic particles, which are then guided by magnetic fields to specific body sites. A detailed treatment of ferrofluid physics can be found in Rosensweig (1985), while more applied aspects are discussed in Raj and Moskowitz (1990), Berkovski et al. (1993), and Berkovski and Bashtovoy (1996), references listed in the Relevant Art section infra.
REFERENCES
The following literature references are known by the inventors to be concerned with various aspects of the characteristics and uses of ferrofluids.
Berkovski, B., and V. Bashtovoy,
Magnetic Fluids and Applications Handbook,
Begell House, Inc., New York, 1996.
Berkovski, B. M., V. F Medvedev, M. S. Krakov,
Magnetic Fluids Engineering Applications,
Oxford Univ. Press, New York, 243 pp., 1993.
Bailey, R. L., Lesser known applications of ferrofluids,
J. Magnetism Magnetic Mater.,
39(1,2), 178-182, 1983.
Borglin, S. E., G. J. Moridis, and C. M. Oldenburg, Experimental studies of magnetically driven flow of ferrofluids through porous media,
Lawrence Berkeley National Laboratory Report
LBL-40126, Berkeley, Calif., March 1998a.
Borglin, S. E., G. J. Moridis, and A. Becker, Magnetic detection of ferrofluid injection zones,
Lawrence Berkeley National Laboratory Report
LBL-40127, Berkeley, Calif., March 1998b.
Chorney, A. F., and W. Mraz, Hermetic sealing with magnetic fluids,
Machine Design,
79-82, May 1992.
Jackson, J. D.,
Classical Electrodynamics,
John Wiley & Sons, New York, 641 pp., 1967, pg. 153-154.
Lunn, S. R. D., B. H. Kueper, Removal of pooled dense, nonaqueous phase liquid from saturated porous media using upward gradient alcohol floods,
Water Resour. Res.,
33(10), 2207-2219, 1997.
Moridis, G. J., S. E. Borglin, C. M. Oldenburg, and A. Becker, Theoretical and experimental investigations of ferrofluids for guiding and detecting liquids in the subsurface,
Lawrence Berkeley National Laboratory Report
LBL-41069, Berkeley, Calif., March, 1998.
Moridis, G. J., L. Myer, P. Persoff, S. Finsterle, J. A. Apps, D. Vasco, S. Muller, P. Yen, P. Williams, B. Freifeld, and K. Pruess, First-Level Field Demonstration of Subsurface Barrier Technology Using Viscous Liquids,
Lawrence Berkeley National Laboratory Report
LBL-37520, Berkeley, Calif., July 1995.
Morimoto, Y., Magnetic guidance of ferro-colloid entrapped emulsion for site-specific drug delivery,
Chemical and Pharmaceutical Bulletin
(Tokyo), 48, 1279-1284, 1983.
Moskowitz, R., Dynamic sealing with magnetic fluids,
ASLE Transactions,
18(2), 135-143, 1975.
Newbower, R. S., A new technique for circulatory measurements employing magnetic fluid tracers, in
Proceedings,
1972
Biomedical Symp.,
San Diego, 1972.
Oldenburg, C. M., S. E. Borglin, and G. J. Moridis, Numerical simulation of ferrofluid flow for environmental engineering applications,
Lawrence Berkeley National Laboratory Report
LBNL-40146, March 1998 and
Transport in Porous Media,
in press.
Raj, K., and R. Moskowitz, Commercial applications of ferrofluids,
J. of Magnetism and Magnetic Materials,
85, 233-245, 1990.
Rao, P. S. C., M. D. Annable, R. K. Sillan, D. Dai, K. Hatfield, W. D. Graham, A. L. Wood, and C. G. Enfield, Field-scale evaluation of in situ cosolvent flushing for enhanced aquifer remediation,
Water Resour. Res.,
33(12), 2673-2686, 1997.
Rosensweig, R. E.,
Ferrohydrodynamics,
Cambridge University Press, 344 pp., 1985.
Senyei, A. E., and K. Widder, Drug targeting: Magnetically responsive albumin microspheres- A review of the system to date,
Gynecology and Oncology,
12(1), 21-33, 1981.
Telford, W. M., L. P. Geldart, and R. E. Sheriff,
Applied Geophysics,
2nd Edition, Cambridge University Press, 1990.
U.S. Pat. No. 5,836,390, issued Nov. 11, 1998.
BRIEF SUMMARY OF THE INVENTION
The invention comprises a process having a number of embodiments for utilizing ferrofluids in the field of environmental engineering with emphasis on subsurface environmental restoration. The various embodiments fall broadly into two main categories: (1) guiding liquids and holding liquids in place in the subsurface through application of magnetic fields; and (2) using ferrofluids as tracers imageable by standard electromagnetic and geophysical methods. The invention, therefore, is a process for guidance, containment, treatment and imaging of below ground substances, such as contaminants, utilizing ferrofluids. The invention is described more fully herein.
REFERENCES:
patent: 2279262 (1942-04-01), Edwards
patent: 2696260 (1954-12-01), Fast
patent: 3300984 (1967-01-01), Armentrout
patent: 4691774 (1987-09-01), Nelson
patent: 4802534 (1989-02-01), Larson et al.
patent: 5465789 (1995-11-01), Evans
patent: 5836390 (1998-11-01), Apps et al.
Moridis George J.
Oldenburg Curtis M.
Aston David J.
Nold Charles R.
Sartorio Henry P.
Suchfield George
The Regents of the University of California
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