WO1999033072A1 - Magnetic liquid and method and device for the production thereof - Google Patents
Magnetic liquid and method and device for the production thereof Download PDFInfo
- Publication number
- WO1999033072A1 WO1999033072A1 PCT/EP1998/008232 EP9808232W WO9933072A1 WO 1999033072 A1 WO1999033072 A1 WO 1999033072A1 EP 9808232 W EP9808232 W EP 9808232W WO 9933072 A1 WO9933072 A1 WO 9933072A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- magnetic
- liquid
- liquids
- magnetic field
- polar
- Prior art date
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C1/00—Magnetic separation
- B03C1/32—Magnetic separation acting on the medium containing the substance being separated, e.g. magneto-gravimetric-, magnetohydrostatic-, or magnetohydrodynamic separation
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/44—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of magnetic liquids, e.g. ferrofluids
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y25/00—Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
Definitions
- the invention relates to a new magnetic liquid and to a method and a device for its production according to the preambles of claims 1, 5 and 18.
- Magnetic liquids are stable dispersions with superparamagnetic properties.
- the solid particles contained in this dispersion as a disperse phase do not sediment either in the earth's gravity or in the magnetic field.
- Magnetic liquids essentially consist of three components.
- the disperse magnetic components are solid particles made of ferro- or ferrimagnetic materials, which have a size of 3 - 50 nm.
- the disperse phase which is in the form of nanometer particles, is stabilized by surfactants.
- the nanometer particles are homogeneously and stably distributed.
- Surfactant molecules are amphiphilic molecules that have both hydrophilic and lipophilic properties. The hydrophilic groups of the surfactants are chemically fixed on the particle surfaces to form monomolecular adsorption layers.
- hydrophilic chemically sorbable molecules are suitable, for example, carboxylic acid groups, sulfonate groups, sulfate groups, phosphate groups or phosphonate or. Amino groups. Both polar and non-polar solvents are suitable as carrier liquids.
- two adsorption layers - an inner and an outer one - are predominantly formed, whereby the amphiphilic molecules of the outer layer can be anionic, cationic or nonionic surfactants and those of the inner layer made of anionic surfactants how fatty acids exist.
- a second outer adsorption layer is required to stabilize the nanometer particles.
- the outer layer becomes hydrophobic through weaker physical interactions
- volume viscosity and its strong increase when the aqueous phase is concentrated and decisively limit the values for the saturation magnetization.
- Saturation magnetization is a measure of the concentration of magnetic particles in the magnetic liquid.
- Magnetic liquids based on water are known. According to DE 195 16 323 AI, they have saturation magnetizations of up to 25 mT.
- the nanometer particles as magnetic components consist of maghemite ( ⁇ -Fe 2 0 3 ), magnetite (Fe 3 ⁇ 4 ) or mixed oxides, such as cobalt ferrite or manganese-zinc ferrite.
- These water-based magnetic liquids also have the disadvantage that they have a relatively high concentration of surfactants in the aqueous phase. This also means that they are relatively highly viscous.
- the high surfactant content prevents larger saturation magnetizations.
- high surfactant levels can be ecologically questionable and economically disadvantageous when producing larger quantities.
- organic-based magnetic liquids are generally treated by reprecipitation according to US Pat. No. 3,917,538 to reduce the surfactant concentration in the dispersion medium.
- the particles precipitate as sediment, and the surfactant-containing dispersant is decanted and replaced by surfactant-free ones. After heating, the particles are redispersed to form a magnetic liquid.
- This process assumes that a suitable precipitant is known and that the surfactant is not detached from the particles by the precipitant. It is therefore an energy-consuming, relatively rough process.
- This method cannot be used for magnetic liquids whose particles are stabilized by an inner and an outer adsorption layer.
- the outer layer which is only physically adsorbed, usually separates from the particles stabilized in the polar dispersion medium.
- Methods for removing the superfluous surfactants from the outer adsorption layer after physical adsorption have hitherto not been known.
- the particles are modified with carboxy-functional polymers, the dispersant containing both the carboxy-functional polymer and non-ionic wetting agent in high concentration.
- the magnetite particles are precipitated in the presence of the carboxy-functional polymers, after which a sediment is formed from the modified particles, which is redispersed in the dispersant of the above-mentioned composition.
- the saturation magnetization of the magnetic fluid formed is below 10 mT.
- the electrical conductivity is very low at 900 ⁇ / cm, and therefore the particles will flocculate when electrolyte is added.
- DE 43 27 826 AI describes magnetic liquids on an aqueous basis, the magnetite particles of which consist of an inner fatty acid and an outer layer of ethoxylated fatty alcohols.
- the dispersant contains a large excess of ethoxylated fatty acids, which a relatively high viscosity of the magnetic fluid and a maximum achievable saturation magnetization of only 25mT.
- the invention has for its object to provide a magnetic liquid with high saturation magnetization, ie. H. to offer with a high concentration of nanometer particles and low viscosity and to provide a method and an apparatus for their production.
- the magnetic liquids according to the invention with an aqueous carrier liquid have hitherto unknown saturation magnetizations between 30 and 100 mT and the viscosity is below 100 mPas
- the surfactant contains essentially no more surfactants, there are both ecological and economic advantages.
- the magnetic liquids according to the invention with high saturation magnetization are produced using the method and the device according to the invention.
- a separation of the surfactants can be achieved.
- the separation is possible by heating the known aqueous magnetic liquids, which are stabilized by an inner and outer adsorption layer on the nanometer particles, to about 30-95 ° C. This leads to a reduction in the solubility of the surfactants in the carrier liquid.
- the heated magnetic liquid is then exposed to an external magnetic field, so that a strong inhomogeneous magnetic field, a magnetic field gradient, is generated in the aqueous magnetic liquid.
- a permanent magnet made of rare earths which has saturation magnetization values of up to 0.5 T on its surface, fixes heated aqueous magnetic liquid to the vessel wall of a vessel.
- the tensides which make up the second outer adsorption layer and are present in high concentration in the aqueous carrier liquid, are separated from the magnetic nanometer particles, taking part of the aqueous carrier liquid with them Crowded surface from which they can drain. What remains is a more concentrated magnetic fluid.
- the concentration of nanometer particles can be gradually increased so that saturation magnetizations of 70 mT can be achieved.
- the Surfactant-free carrier liquid achieves astonishingly low viscosities of concentrated magnetic liquids, which are between 5 and 30 mPas at 27 ° C.
- Another advantage of this concentration process is that the dissolved surfactant can be recovered from the carrier liquid, which was separated from the nanometer particles by the process according to the invention, by evaporation and can thus be used again in the production of an aqueous magnetic liquid.
- Fig. 1 shows a device for quasi-continuous
- FIG. 2 shows a device for discontinuous separation.
- a magnetic liquid 10 to be concentrated is located in a container 1.
- a heating device 5 is arranged below the container 1.
- a feed line 8 leads from the bottom of the container 1 to separating surfaces 2. The feed line 8 is to be closed and opened via a shut-off valve 9. Above the separating surface 2, two strong magnets 3 and 4 are arranged one after the other in their immediate vicinity. The separating effect can be optimized via the angle of attack of the separating surface 2.
- a magnetic trough 7 and a surfactant trough 6 are arranged below the separating surface 2.
- the magnetic liquid 10 flows via the feed line 8 to the lower surface of the separating surface 2. Due to the existing magnetic field gradient, which is generated by the magnet 3, a bulge-like accumulation of the magnetic liquid 10 forms at the separating surface 10 The first surfactant droplets enriched with carrier liquid dissolve and fall into the Surfactant trough 6. After the magnet 3 has been switched off and the magnet 4 has been switched on at the same time, the magnetic fluid 10 is drawn onto the separating surface below the magnet 4. A further separation of surfactants takes place here. The remaining highly concentrated magnetic liquid 10 is then collected after switching off the magnet 4 m of the magnet trough 7.
- the magnetic liquid 10 is heated by means of the heating device 5 in the first step.
- the magnetic liquid ie. H. the nanometer particles present accumulated on the interface 2.
- the concentration process at the separating surface 2 is completed and the concentrated particles can be drawn off downwards. The more concentrated magnetic liquid drawn off can then be introduced again into the container 1 and a further separation process can follow.
- a 15 mT magnetic liquid on an aqueous basis which consists of
- Magnetite particles which have a layer of lauic acid anchored to the particle and a second nonionic layer of ethoxylated alcohols Ethoxy groups are concentrated as follows: 100 ml of the magnetic fluid is heated to 80 ° C in a refractory vessel. Then a side-earth permanent magnet, which has a saturation magnetization of 0.3 T on its surface, is attached to the outside of the wall of the vessel, so that the • magnetic flux is held on the opposite side of the magnet. After a few minutes, the separation of a non-magnetic viscous solution from the magnetic fluid begins. The magnetic fluid concentrated over time forms the typical peaks after a while and is increasingly fixed to the magnet.
- the deposition process can be supported by keeping the magnetic fluid in motion either by moving the magnet or by mechanical mixing of the magnetic fluid or by heating the magnetic fluid again to 80-90 ° C.
- the end product has a saturation magnetization of 50mT and a kinematic viscosity at 27 ° C of 5 mPas.
- the Ms value By evaporation of the aqueous phase, the Ms value could be increased to 80 mT, the viscosity of the magnetic fluid increasing to only 70 mPas. A further 7 evaporation gave a very viscous magnetic dispersion with an Ms value of 100 mT.
- a 10 T aqueous magnetic flux containing magnetite particles which consists of a layer of oleic acid anchored to the particle and a second nonionic layer of sorbitan monooleate is treated as follows:
- the magnetic fluid is heated to 90 ° C in a container.
- a permanent magnet on the side which is covered with a foil, is placed directly into the magnetic fluid.
- the magnetic fluid that remains on the magnet is transferred to a new vessel, where the separation is carried out.
- the end product reaches an Ms value of 50 mT with a viscosity at 27 ° C of 10 mPas.
- a 20 mT magnetic fluid on an aqueous basis which contains cobalt ferrite particles as a magnetic component, but otherwise consists of the surfactant layers mentioned in the example, is carried out as follows in a semi-continuous process: the magnetic fluid is first heated to 80.degree. A strong electromagnet is attached to a glass pane or a plastic board and set up at a slight angle. The heated magnetic fluid is then brought to the underside of the pane or board via a hose-like feed. The deposition process begins, with the surfactant solution dripping from the magnetic fluid onto the floor. Magnetic fluid is continuously fed to the magnet until the concentrated magnetic fluid is accumulated in such a large amount that a part of it also threatens to flow away from the magnet.
- the end product is medium conc. Bring the ammonium chloride solution to a pH> 8, the particles being redispersed.
- the end product has an Ms value of 60 mT with a viscosity of 5 mPas.
- the starting magnetic fluid is an alkaline aqueous magnetite magnetic fluid in which the particles are stabilized by an inner adsorption layer made of lauric acid and an outer adsorption layer made of the ammonium salt of lauric acid in accordance with US Pat. No. 4,228,294 and whose saturation magnetization is 15 mT.
- the surfactants dissolved in the aqueous carrier liquid are brought to the formation of surfactant aggregates by slow addition of ethanol and dilute hydrochloric acid solution, without the magnetic flux being destroyed. Then part of the dispersion medium and the surfactants contained therein are separated in a magnetic field gradient. Then becomes concentrated magnetic fluid is adjusted to an alkaline pH by adding ammonium hydroxide.
- the saturation magnetization of the concentrated magnetic fluid is 80mT with a viscosity at room temperature of 100mPas.
- a magnetite magnetic fluid based on petroleum, stabilized with a monolayer of oleic acid and a saturation magnetization of 30mT is used as the starting magnetic fluid.
- the oleic acid contained in petroleum is condensed by adding ethanol in a ratio of 1: 2. After exposure to an external magnetic field, the saturation magnetization is increased to 100mT, the viscosity being 20mPas at 27 ° C.
Abstract
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1020007006979A KR20010033478A (en) | 1997-12-22 | 1998-12-17 | Magnetic liquid and method and device for the production thereof |
EP98965839A EP1051715A1 (en) | 1997-12-22 | 1998-12-17 | Magnetic liquid and method and device for the production thereof |
JP2000525894A JP2001527283A (en) | 1997-12-22 | 1998-12-17 | Magnetic fluid, its manufacturing method and its manufacturing apparatus |
AU21622/99A AU2162299A (en) | 1997-12-22 | 1998-12-17 | Magnetic liquid and method and device for the production thereof |
CA002315704A CA2315704A1 (en) | 1997-12-22 | 1998-12-17 | A magnetic fluid, a process and a device for its production |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19758350A DE19758350C1 (en) | 1997-12-22 | 1997-12-22 | Magnetic fluid comprising magnetic nano-particles dispersed in a polar carrier fluid |
DE19758350.4 | 1997-12-22 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1999033072A1 true WO1999033072A1 (en) | 1999-07-01 |
Family
ID=7853655
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/EP1998/008232 WO1999033072A1 (en) | 1997-12-22 | 1998-12-17 | Magnetic liquid and method and device for the production thereof |
Country Status (9)
Country | Link |
---|---|
EP (1) | EP1051715A1 (en) |
JP (1) | JP2001527283A (en) |
KR (1) | KR20010033478A (en) |
CN (1) | CN1285950A (en) |
AU (1) | AU2162299A (en) |
CA (1) | CA2315704A1 (en) |
DE (1) | DE19758350C1 (en) |
RU (1) | RU2203516C2 (en) |
WO (1) | WO1999033072A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9409148B2 (en) | 2013-08-08 | 2016-08-09 | Uchicago Argonne, Llc | Compositions and methods for direct capture of organic materials from process streams |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102006041495A1 (en) * | 2006-08-29 | 2008-03-20 | Friedrich-Schiller-Universität Jena | Substance mixture, useful for locally limited of magnetic nanoparticle within or directly at the edge of tumor affected physical tissue, where the magnetic particle is mixed with a fluid thixotropic carrier substance |
UA87177C2 (en) | 2007-07-04 | 2009-06-25 | Государственное Предприятие "Международный Центр Электронно-Лучевых Технологий Института Электросварки Им. Е.О.Патона Национальной Академии Наук Украины" | method of producing nanoparticles for magnetic fluids by electron-beam evaporation and condensation in vacuum, method of producing magnetic liquid and magnetic liquid produced by said method |
CN102441488B (en) * | 2011-09-06 | 2013-07-31 | 北京交通大学 | Slide-type gas-liquid interface jigging magnetic separation controllable device |
US11368078B2 (en) | 2017-04-14 | 2022-06-21 | Carrier Corporation | Electrical machine winding inductance enhancement |
CN107195419A (en) * | 2017-08-02 | 2017-09-22 | 新疆大学 | Ethylene glycol magnetic fluid and preparation method thereof |
CN108037700A (en) * | 2017-12-13 | 2018-05-15 | 杭州电子科技大学 | A kind of magnetic current body controlling means |
WO2019187293A1 (en) | 2018-03-30 | 2019-10-03 | 富士フイルム株式会社 | Separation device and separation method |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH04107802A (en) * | 1990-08-28 | 1992-04-09 | Nippon Seiko Kk | Production of magnetic fluid |
DE4327826A1 (en) * | 1993-08-16 | 1995-03-16 | Ikosta Gmbh Inst Fuer Korrosio | Magnetic liquid |
DE19514515A1 (en) * | 1995-04-12 | 1996-11-21 | Dirk Dipl Chem Guenther | Magnetisable iron oxide nano-particle dispersion with high saturation polarisation |
US5667716A (en) * | 1996-07-01 | 1997-09-16 | Xerox Corporation | High magnetization aqueous ferrofluids and processes for preparation and use thereof |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3917538A (en) * | 1973-01-17 | 1975-11-04 | Ferrofluidics Corp | Ferrofluid compositions and process of making same |
US4208294A (en) * | 1979-02-12 | 1980-06-17 | The United States Of America, As Represented By The Secretary Of The Interior | Dilution stable water based magnetic fluids |
US5240626A (en) * | 1990-09-21 | 1993-08-31 | Minnesota Mining And Manufacturing Company | Aqueous ferrofluid |
DE19516323C2 (en) * | 1995-04-27 | 1997-02-27 | Dirk Dipl Chem Guenther | Process for the preparation of magnetizable dispersions and their use |
-
1997
- 1997-12-22 DE DE19758350A patent/DE19758350C1/en not_active Expired - Fee Related
-
1998
- 1998-12-17 KR KR1020007006979A patent/KR20010033478A/en not_active Application Discontinuation
- 1998-12-17 JP JP2000525894A patent/JP2001527283A/en active Pending
- 1998-12-17 CN CN98813070A patent/CN1285950A/en active Pending
- 1998-12-17 CA CA002315704A patent/CA2315704A1/en not_active Abandoned
- 1998-12-17 AU AU21622/99A patent/AU2162299A/en not_active Abandoned
- 1998-12-17 EP EP98965839A patent/EP1051715A1/en not_active Withdrawn
- 1998-12-17 WO PCT/EP1998/008232 patent/WO1999033072A1/en not_active Application Discontinuation
- 1998-12-17 RU RU2000119040/02A patent/RU2203516C2/en not_active IP Right Cessation
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH04107802A (en) * | 1990-08-28 | 1992-04-09 | Nippon Seiko Kk | Production of magnetic fluid |
DE4327826A1 (en) * | 1993-08-16 | 1995-03-16 | Ikosta Gmbh Inst Fuer Korrosio | Magnetic liquid |
DE19514515A1 (en) * | 1995-04-12 | 1996-11-21 | Dirk Dipl Chem Guenther | Magnetisable iron oxide nano-particle dispersion with high saturation polarisation |
US5667716A (en) * | 1996-07-01 | 1997-09-16 | Xerox Corporation | High magnetization aqueous ferrofluids and processes for preparation and use thereof |
Non-Patent Citations (1)
Title |
---|
PATENT ABSTRACTS OF JAPAN vol. 016, no. 347 (E - 1240) 27 July 1992 (1992-07-27) * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9409148B2 (en) | 2013-08-08 | 2016-08-09 | Uchicago Argonne, Llc | Compositions and methods for direct capture of organic materials from process streams |
Also Published As
Publication number | Publication date |
---|---|
DE19758350C1 (en) | 1999-03-11 |
CA2315704A1 (en) | 1999-07-01 |
JP2001527283A (en) | 2001-12-25 |
AU2162299A (en) | 1999-07-12 |
KR20010033478A (en) | 2001-04-25 |
EP1051715A1 (en) | 2000-11-15 |
CN1285950A (en) | 2001-02-28 |
RU2203516C2 (en) | 2003-04-27 |
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