Liquid purification or separation – Processes – Making an insoluble substance or accreting suspended...
Reexamination Certificate
2002-06-28
2004-11-23
Hopkins, Robert A. (Department: 1724)
Liquid purification or separation
Processes
Making an insoluble substance or accreting suspended...
C210S712000, C210S729000, C210S737000
Reexamination Certificate
active
06821439
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to water purification and more particularly to water purification using organic additives that include organic salts and salts of organic polymers.
BACKGROUND OF THE INVENTION
A reliable supply of fresh water is necessary for human consumption, for energy conversion technologies, for irrigation, and for other important uses. Many populated areas are in short supply of fresh water and must rely on water purification technologies such as desalination to provide for, or at least add to, their supply of fresh water. Middle Eastern countries, the Canary Islands, and Mauritius, for example, rely on desalination plants to produce fresh water from seawater. Seawater is a complex substance having a high concentration of sodium chloride and a wide variety of other impurities. Desalination removes most of the sodium chloride and other impurities to produce purified water.
A variety of desalination methods have been reported. They include gas-hydrate formation methods and high-pressure, reverse osmosis methods. Gas hydrate formation methods were examined during an intense period of desalination research from about 1960-1980. A gas hydrate formation method might involve pumping an additive gas though a long tube hundreds of feet below the surface of the sea. Under these conditions of high pressure and low temperature, molecules of additive gas combine with water molecules from the seawater to form a solid, crystalline clathrate known as a “gas hydrate”. The crystalline gas hydrate includes gas molecules trapped inside cages of tightly bound water molecules. The crystalline gas hydrate is physically separated from the seawater and/or brine (the brine includes the impurities removed from the seawater) and washed to remove any impurities coated on the gas hydrate crystals. The washed crystals are then degassed to produce fresh water. The additive gas may be recovered, recompressed, and recycled if desired.
Current reverse-osmosis desalination methods require high pressures and employ membranes that filter away many of the impurities from “feed water” (i.e. water with undesired impurities to be removed) and reduce the salt levels to 300 ppm in a single pass. While these membranes are very effective, they are also subject to fouling and scaling from impurities in the feed water. Efforts to eliminate fouling by pretreating the feed water with chlorine to kill bacteria and algae, and to eliminate scaling by adjusting the pH of the feed water to minimize precipitation of insoluble calcium salts and silica, have been met with limited success. Membrane fouling and scaling remains a constant problem. Moreover, reverse osmosis processes are very expensive due to high-pressure requirements, typically 70-80 bar.
In 1996, the Desalination and Water Purification Research and Development Program was authorized by Congress. Information relating to this program can be found at the following website: www.usbr.gov/water/content/c_desal.html. The primary goal of the Program is the development of a “cost-effective, technologically efficient, and implementable” means to desalinate water. This program has provided support for the development of new membranes, the application of gas hydrate-assisted desalination, and the design of pumps and vessels, and pilot plant scale testing. While pilot plant scale testing indicated that the energy cost for the production of one cubic meter of fresh water from seawater could be reduced, it remains unlikely that current desalination technology is economically viable in competitive markets. Thus, there remains a need for more efficient water purification methods such as desalination.
Therefore, an object of the present invention is to provide an efficient water purification method.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
SUMMARY OF THE INVENTION
In accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention includes a water purification method. The method includes contacting feed water with at least one organic salt at a temperature sufficiently low to form brine and organic salt hydrate crystals. The organic salt hydrate crystals are separated from the brine, rinsed with fresh water, and melted to form a solution comprising water and at least one organic salt. Fresh water is then separated from the solution.
REFERENCES:
patent: 2904511 (1959-09-01), Donath
patent: 3415747 (1968-12-01), Glew
patent: 4207351 (1980-06-01), Davies
patent: 4678583 (1987-07-01), Willson, III et al.
patent: 5553456 (1996-09-01), McCormack
patent: 6158239 (2000-12-01), Max et al.
patent: 6159379 (2000-12-01), Means et al.
D. L. Fowler, W. V. Loebenstein, D. B. Pall, and Charles A. Kraus, “Some Unusual Hydrates of Quaternary Ammonium Salts,” Contribution from the Metcalf Research Laboratory of Brown University, vol. 62, pp. 1140-1142, May 1940.
Richard McMullan and G. A. Jeffrey, “Hydrates of the Tetra n-butyl and Tetra i-amyl Quaternary Ammonium Salts,” The Journal of Chemical Physics, vol. 31, No. 5, pp. 1231-1234, Nov. 1959.
Irene S. Terekhova, Vladimir L. Bogatyryov, and Yuri A. Dyadin, “Composition of the Clathrate Polyhydrate of a Carboxyl Cationite in the Tetraisoamylammonium Form, ” Mendeleev Communications Electronic Version, Issue 1, 1998.
Yuri A. Dyadin and Lyudmila S. Aladko, “Clathrate Hydrates of Long-Chain Tetgrabutylammonium Carboxylates,” Mendeleev Communications Electronic Version, 1995.
Richard A. McCormack and Richard K. Andersen, “Clathrate Desalination Plant Preliminary Research Study,” Water Treatment Technology Program Report No. 5, Jun. 1995.
Roy Popkin, “Desalination, Water for the World's Future, ” Frederick A. Praeger, Publishers, pp. 17.
A. Delyannis E.-E. Delyannis, “Seawater and Desalting, ” Springer-Verlag, Berlin Heidelberg, New York, vol. 1, pp. 169-171, 1980.
Everett D. Howe, “Fundamentals of Water Desalination, ” Marcel Dekker, Inc, New York, pp. 80,1974.
K. S. Spiegler, “Salt-Water Purification, ” John Wiley & Sons, Inc., New York—London, pp. 110-111.
K. S. Spiegler, “Principles of Desalination, ” Academic Press, pp. 339-343, 1966.
Konstantin A. Udachin and John A. Ripmeester, “A Polymer Guest Transforms Clathrate Cages into Channels. The Single-Crystal X-Ray Structure of Tetra-n-butylammonium Polyacrylate Hydrate, nBU2O2” Angew. Chem. Int. Ed., vol. 38, No. 13/14, pp, 1999.
Haruo Nakayama and Ryoichi Yamada, “The Effect of Simple Anions on the Formation of Poly(tetraisopentylammonium Acrylate) Hydrates,” Thermochimica Acta, vol. 250, pp. 97-107, 1995.
Haruo Nakayama and Kei Baba, “Hydrates of Organic Compounds. XVIII, The Formation of Hydrates of Tetraisopentylammonium Salts Having Polyanions,” Bull. Chem. Soc. Jpn., vol. 66, No. 12, pp. 3585-3588, 1993.
Haruo Nakayama and Ryoichi Yamada, “Hydrates of Organic Compounds. XVII, The Effects of Cations on the form of Hydrates of Poly(tetraisopentylammonium Acrylate,” Bull. Chem. Soc. Jpn., vol. 65, No. 10, pp. 2704-2708, 1992.
Haruo Nakayama, Masashi Yamanobe, and Kei Baba, “Hydrates of Organic Compounds. XVI, Determination of the Melting Points and Hydration Numbers. of the Hydrates of Tetrabutyl(or Tetraaisopentyl)ammonium Alkanesulfonates,” Bull. Chem. Soc. Jpn., vol. 64, No. 10, pp. 3023-3028, 1991.
Haruo Nakayama, Kayoko Nakamura, Yukio Haga, and Yoji Sugiura, “Hydrates of Organic Compounds. XV, The Formation of Clatrate-Like Hydrates of Tetraisopentylammonium Alkanoates and Alkanedoioates,” Bull. Chem. Soc. Jpn., vol. 64, No. 2, pp. 358-365, 1991.
Haruo Nakayama, Hiromi Kuwata, Norikazu Yamamoto, Yutaka Akagi, and Hiroshi Matsui, “Solubilities and Dissolution States of a Series of Symmetrica
Borkowsky Samuel L.
Hopkins Robert A.
The Regents of the University of California
LandOfFree
Water purification using organic salts does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Water purification using organic salts, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Water purification using organic salts will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3361094