Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D11/00—Solvent extraction
  • B01D11/04—Solvent extraction of solutions which are liquid
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N1/00—Sampling; Preparing specimens for investigation
  • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
  • G01N1/34—Purifying; Cleaning
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N1/00—Sampling; Preparing specimens for investigation
  • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
  • G01N1/40—Concentrating samples
  • G01N1/4055—Concentrating samples by solubility techniques
  • G01N2001/4061—Solvent extraction

Definitions

• the present invention relates to a method for extraction of extractable components, such as dissolved substances, colloidal and/or suspended particles, in liquids.
• the invention relates especially to an on-line flow extraction method including the following consecutive steps:
• the present invention also relates to an apparatus for on ⁇ line flow extraction of extractable components, such as dissolved substances, colloidal and/or suspended particles, in a liquid.
• extractable components such as dissolved substances, colloidal and/or suspended particles
• a central need in analytical chemistry is to be able to work up and concentrate different samples of substances in order to be able to perform chemical analysis. Secondary or interfering matrix components have to be removed, whereas components, which are to be analyzed, often are extracted into a medium, which is compatible with the subsequent analysis method. This step usually also leads to concentration of the components.
• Liquid/liquid extraction techniques commonly used today include manual/mechanical shaking or mixing of the sample with extraction medium or solvent.
• flow extraction systems with continuous liquid/liquid extraction are known. These systems include a continuous and controllable introduction of solvent into a stream of sample to be analyzed.
• Flow Injection Analysis In these Flow Injection Analysis (FIA) systems discrete segments of the sample and the extraction medium are formed. A gradual extraction occurs in an extraction coil or tube, the time needed to obtain an equilibrium depending on the extraction kinetics.
• the FIA systems usually employ a tube with a T-connection for introducing extraction medium into the flow of sample.
• This system has e.g. been used for analyzing waste water or drugs present in water-based solutions.
• Coaxially arranged tubes may be used besides the aforementioned tube with a T- connection.
• a problem arises, however, when colloidal substances, such as fat droplets in water, or very fine particles suspended in water, are to be extracted.
• colloidal or very finely dispersed substances may e.g. have a negative surface charge which stabilizes the colloidal state.
• other mechanisms such as steric stabilization through formation of a protective polymer layer on the finely dispersed droplets, further stabilizes the colloidal or suspended state. This situation has been noticed to occur e.g. when fat/resin droplets formed in paper mill process waters are covered by a thin layer of hemicellulose.
• the extraction medium the solvent, is thereby finely dispersed and a forced contact between colloidal particles and extraction medium is accomplished.
• an on-line flow extraction can be efficiently performed also of colloidal or suspended particles in a liquid by injecting the solvent or extraction medium as a high velocity jet stream into the flow of sample in an extraction tube.
• a narrow inlet passage or nozzle between the extraction tube and solvent inlet combined with a high pressure at the solvent inlet usually in the range of 25 - 400 bar, is needed.
• the jet stream formed has a high enough kinetic energy for the solvent to immediately disintegrate into fine droplets having an impact on colloidal or suspended particles in the sample flow.
• the solvent is preferably disintegrated into fine droplets having a diameter of about 0.1 - 10 ⁇ m.
• the kinetic energy of the jet formed should preferably be high enough for the jet to be able to penetrate the flow of sample and hit the opposite inner side wall of the extraction tube.
• the jet reaching the other side wall should still have a kinetic energy high enough to be at least partly reflected from that other side wall back into the flow of sample.
• extraction tube is here used for a wide variety of tubes or channels in which extraction medium, such as organic solvent, is mixed into the flow of sample.
• the extraction tube may be a tube or an extraction channel formed between two plates or some other suitable construction.
• narrow inlet passage is here used for a wide variety of nozzles or small openings, such as capillary nozzles, narrow bore capillaries or capillaries with a narrow bore insert, simple narrow bores, circular or non- circular in shape, which may be used to inject solvent into the extraction tube.
• colloidal or suspended particles refers here to liquid, as well as, solid particles in a more or less stable colloidal or suspended form.
• the flow of sample liquid including dissolved, colloidal and/or suspended material, is continuously or intermittently pumped or conveyed by suction through an extraction tube or sample tube.
• a second liquid, the extraction medium or solvent is introduced into the extraction tube through a solvent inlet tube.
• the second liquid is injected at high pressure providing a high velocity via one or several narrow inlet passages.
• a solvent inlet tube may be directly or indirectly connected to the extraction tube.
• the outlet end of a solvent inlet tube which is directly connected to an opening in the side wall of an extraction tube, may itself be small enough to provide the narrow inlet passage or nozzle needed for injecting the solvent.
• a narrow bore capillary insert may be placed in the outlet end of an inlet tube of ordinary dimensions to provide the narrow inlet passage.
• only a very small opening/bore may be made in the side wall of the extraction tube for providing the inlet passage needed between the tubes.
• a narrow bore or other suitable narrow opening may be made in the side wall of the extraction tube, to provide for the narrow inlet passage needed for injecting solvent.
• the extraction tube i.e. the sample tube
• the narrow inlet passages used to inject solvent into the extraction tube may be constructed, as mentioned earlier, in several different ways but should preferably, when circular, have an inner diameter of about 5 - 20 ⁇ m. It is further advantageous that the narrow inlet passages are made as short as possible, in order to prevent the need for excessive pressures for injecting the solvent at the inlet. Only very short capillary nozzles or short narrow bore inserts should be used in order not to increase pressure drop unduly. Narrow inlet passages made directly in the side wall of the extraction tube may have a funnel like shape converging toward the extraction tube.
• the extraction medium By injecting the extraction medium at a high flow velocity into the sample flow, the extraction medium is dispersed into very small micro droplets, which are vigorously mixed with the flow of samples leading to an efficient extraction process.
• the micro drops formed have a high kinetic energy, 1/2 mv 2 , analog e.g. to the action of a water jet of a high pressure cleaning gun, used for cleaning solid surfaces.
• the high kinetic energy leads to forced collisions and efficient contact between the micro drops of solvent and colloidal or other particles present in the sample flow.
• the pressure needed in order to obtain the objectives of the present invention may vary within a wide range depending upon specific sample flow, the specific extraction medium and the apparatus used. The man skilled in the art will, however, find no difficulties in establishing the pressure needed to disperse the extraction medium in a sufficient manner.
• the high pressure injection of extraction medium results in an effective and almost momentary extraction of colloidal and suspended substances. An equilibrium is, however, also simultaneously achieved between substances dissolved in the flow of samples and the extraction medium. Eventually a coalescence of micro drops into larger drops and segments of extraction medium will occur downstream of the injection point in the extraction tube.
• the extraction medium segments can be separated in a phase separator as a continuous flow from the flow of sample. Different types of continuous phase separators, described in literature, may be used for separation of the two phases.
• a pressure optimized porous PTFE membrane separator for instance allows only organic solvent to pass the pores in the membrane, whereas a water phase is not able to wet the membrane. In a settler, different phases are simply separated due to their difference in densities.
• two or more narrow inlet passages may be arranged in series or parallel.
• a repeated extraction process takes place, which will increase the efficiency of the extraction process and further improve the yield of the extraction.
• different extraction mediums, solvents may be introduced through the different inlet passages, if different components are to be extracted in successive steps. Introducing solvent through several parallel inlet passages is useful when larger sample flows are to be analyzed, as it increases the capacity of the extraction process.
• the narrow inlet passage(s), e.g. the capillary nozzles, are preferably arranged to direct the inlet flow of extraction medium, e.g. an organic solvent, perpendicularly into the sample flow.
• extraction medium e.g. an organic solvent
• the new method and apparatus may be used to extract components that are permanently or only momentarily present in a liquid in a dissolved, colloidal or suspended state.
• a suspension of water and a solid or liquid medium, including the extractable component may e.g. in some applications be prepared by mixing solid particles into water only immediately before injecting the extraction medium into the water. The suspension thus prepared may only be stable for a time period long enough for the extraction to take place.
• the new method and apparatus may e.g. be used not only for analysis of components, but also for extraction of components from colloidal or suspended particles, in order to produce a product including these components.
• the new method and apparatus may further be applied for separating solid components from the surface of solid particles suspended in a liquid.
• the jet of extraction medium having a very high velocity, i.e. high kinetic energy, may be used to "peel" off certain layers of solid material from solid particles suspended in e.g. water.
• FIG. 1 shows a schematic cross sectional view of a T- connection tube used in a conventional flow extraction system for injecting extraction medium into a flow of sample to be analyzed
• FIG.2 shows a schematic cross sectional view of a T- connection tube used for injecting extraction medium in accordance with the present invention
• FIG. 3 shows a schematic cross sectional view of another apparatus, according to the present invention.
• FIG. 4 shows a cross section of the apparatus in FIG 3 along line AA' ,
• FIG. 5 shows a schematic cross sectional view of still another apparatus according to the present invention
• FIG. 6 shows an enlarged view of the encircled portion in FIG. 5
• FIG. 7 shows a schematic cross sectional view of a further apparatus according to the present invention.
• FIG. 8 shows a cross section of the apparatus shown in FIG. 7 along line BB' and
• FIG. 9 shows a top view of the apparatus in FIG.7.
• FIG. 1 shows a schematic cross sectional view of a T- connection tube 10 used in a conventional flow extraction system (FIA) for injecting extraction medium into a flow of sample, which is to be analyzed.
• the T-connection tube includes a main tube 12 and a branch tube 14.
• a flow of sample 16 to be analyzed is pumped or suctioned through the main tube 12 in the direction shown by the arrow.
• Extraction medium 18 is introduced into the main tube through the branch tube 14 connected to an opening 20 in the side wall 22 of the main tube 12.
• Extraction medium which is immiscible with the sample to be analyzed or extracted, flows out from the branch tube 14 into the main tube 12 forming large discrete segments 24.
• the extraction medium e.g. a hydrocarbon
• the sample e.g. a water based solution
• Solvent-soluble dissolved substances in the sample are extracted at an acceptable speed into the extraction medium.
• FIG. 2 shows a T-connection tube 10 used as an extraction apparatus, in accordance with the present invention.
• the apparatus includes a main tube 12, i.e. the extraction tube, having a continuous flow of sample therein, and a branch tube or capillary 14, i.e. the solvent inlet tube, connected directly and perpendicularly to the side wall 22 of the main tube 12.
• a very small inlet opening 26, i.e. the narrow inlet passage, is formed in the side wall 22 for connecting the branch tube 14 with the main tube 12.
• a high pressure pump not shown, is connected to the branch tube 14 for forcing the extraction medium at a high velocity through the small inlet opening 26, whereby a jet stream of high velocity extraction medium is obtained in the main tube 12.
• the direction of the jet stream is perpendicular to the flow direction of liquid in the main tube.
• the jet of extraction medium is immediately dispersed in a large number of micro droplets 28 and is thereby very well mixed with the sample flow. An efficient and almost momentary extraction takes place. Downstream of the injection point 30 micro droplets 28 coalescence into larger droplets 28' and further downstream into still larger segments 28' ' .
• the large segments 28" are separated from the flow of sample in a phase separator not shown.
• the main tube 12 and the branch tube 14 may be made of metal, glass, silica or some other suitable material.
• one branch tube is connected perpendicular to the side wall of the main tube.
• it may be suitable to connect several branch tubes in series or use other types of branch connections, such as Y-connections or W-connections known per se.
• FIG. 3 and FIG. 4 show another variation of the T- connection tube.
• the section 32 of the main tube 12 including a harrow inlet opening 34 is coaxially surrounded by another tube 36 having a slightly larger diameter.
• the outer tube 36 is welded gas tight around to the main tube 12 to form an annular space 38 between the tubes 12 and 36.
• the annular space 38 is pressurized with extraction medium through a branch tube 14, which is connected to the gas space through an opening 40 in the side wall 42 of the outer tube 38.
• the tube 14 is thereby indirectly connected to the main tube 12.
• the opening 40 between the tube 14 and the annular space 38 may be of ordinary dimensions.
• the inlet opening 34, formed in the side wall of the main tube and connecting the annular space 38 with the inside of the main tube 12, is made as a very small diameter bore, e.g. having a diameter of about 5 - 10 ⁇ m.
• a high pressure pump is connected to the branch tube and used to force the extraction medium to flow through the narrow inlet opening 34 into the main tube 12 at a flow velocity of e.g. 0.5 - 1 ml/min.
• the sample is pumped through the main tube 12 with a flow velocity of e.g. 2 ml/min.
• FIG. 3 and 4 utilizes as a test or main tube 12 a thin-walled steel tube, having a 0,1 mm material thickness.
• the small diameter bore or inlet opening 34 may be drilled in the thin-walled steel tube 12 with a laser, whereby the bore forms a nozzle with a very small length.
• FIG. 5 and 6 show another extraction apparatus according to the present invention.
• a thin-walled glass or fused silica capillary tube 14 having an inner diameter of about 150 - 250 ⁇ m, is connected to a main glass tube 12, having an inner diameter of about 1 mm.
• the capillary tube 14 is glued with silicone glue, or any other solvent resistant glue, to the glass tube 12.
• inner piece of glass or fused silica capillary 46 is inserted into the end 48 of the capillary tube 14 before it is connected to the main tube.
• the outer diameter of the inserted inner piece of capillary 46 corresponds to the inner diameter of the outer capillary tube 14.
• the inner piece of capillary is glued with a polyimide glue 50 or other solvent resistant glue to the end 48 of the outer capillary tube 14.
• the inner diameter 44 of the separately inserted inner piece 46, forming the narrow inlet passage between the solvent inlet tube 14 and the extraction tube 12, may be very small e.g. about 5 - 10 ⁇ m.
• the combined capillary construction 14 and 46 is glued with a silicone glue 52 to an opening 44 prebored in the glass tube 12.
• the end 48 of the combined capillary is connected to inject solvent perpendicularly to the direction of flow in the glass tube 12.
• the silica tube 14 is pressurized with extraction medium, with e.g. a high performance liquid chromatography HPLC pump, to a pressure preferably between 50 - 400 bar, while simultaneously conveying a flow of the sample through the glass tube 12 with a low pressure pump, 0.5 - 1 bar, such as a peristaltic pump.
• extraction medium e.g. a high performance liquid chromatography HPLC pump
• FIG. 7 to FIG. 9 a further construction of an extraction apparatus according to the present invention is shown.
• This construction provides a very small/miniature flow extraction apparatus applicable e.g. in clinical biochemistry or for determination of drugs in pharmaceutical preparations.
• the extraction tube i.e. the main channel 54
• the channel m .y be made extremely small suitable for very small sample flows.
• the main channel 54 which in this application has a non-circular cross-section is formed between the plates 56 and 58 by etching a channel onto the surface of plate 58. Further a small narrow inlet opening 60 is formed in the channel 54 by etching an opening, e.g. a square hole or a slot, in plate 56. By etching in onocrystalline silicon it is possible to form extremely small channels and openings, which have a high accuracy.
• the silicon plates 56 and 58 may be connected to each other by gluing, anodic bonding, heating or other suitable methods known per se.
• a cover plate 62 is arranged to cover the inlet opening 60 on the external side of plate 56.
• a gas tight space 64 is thereby formed between the cover plate 62 and plate 56.
• a capillary tube 14 (not shown) is connected to an opening 66 in the cover plate for introducing extraction medium into the space 64.
• the gas tight space 64 is pressurized by extraction medium, which is introduced with a high pressure pump through opening 66. High pressure extraction medium is forced to flow through opening 60 from space 64 into the flow of sample in the channel 54.
• the combined plates may be enclosed in a gas tight outer tube or chamber, instead of using a cover plate 62 to form the gas tight space 64.
• the gas tight outer tube or chamber may then be pressurized with the extraction liquid.
• the main advantages achieved with a silicon construction are high accuracy, as well as, an extremely narrow solvent inlet passage.
• the inlet pressure needed to force a high velocity solvent jet through the narrow inlet passage is lower than in other cases due to the lower pressure drop in the extremely short passage.
• One further advantage achieved is the possibility to arrange a large scale manufacture of identical extraction units, similar to fabrication of electronic components, which leads to a very low manufacturing cost by the piece.
• thermomechanical pulp (TMP) suspension diluted in water to a concentration of 1 %, being freed of coarse fibers or other particles and having a pH 3.0 to 3.5 were prepared.
• the TMP solution included both dissolved and colloidal substances (DCS) .
• DCS dissolved and colloidal substances
• a manual extraction of the DCS sample was undertaken in order to obtain a reference.
• a 4.00 ml DCS sample was measured into a test tube, then 2.00 ml methyl tert-butyl - ether (MTBE) was added.
• the sample was vigorously shaken by hand for 2 minutes and was then centrifuged at 1500 r/min for 5 minutes.
• the clear MTBE-layer was carefully pipetted off. This extraction was repeated twice with two 2 ml portions of pure MTBE.
• the MTBE solutions were combined and then evaporated in a stream of nitrogen. The dried residue was further analyzed by gas chromatography (GC) .
• GC gas chromatography
• the FIA extraction apparatus consisted of a length of glass capillary 14, having an inner diameter of 150 ⁇ m, fixed by silicone glue into the side wall 22 of a glass tube 12, having an inner diameter of 1 mm,
• HPFE high pressure flow extraction
• the ancillary equipment in both examples 2 and 3 consisted of a HPLC pump, delivering 1.05 ml/min of pure MTBE to the 150 ⁇ m capillary 14.
• the pressure drop over the capillary was ca. 2 bar.
• the pressure drop was ca. 285 bar.
• the DCS sample was pumped at a velocity of 0.70 ml/min into the 1 mm glass tube 12 using a peristaltic pump.
• a length of Teflon tubing l m length and 0.70 mm inner diameter, to form larger segments of the phases.
• the apparatus was run for several minutes prior to the first sample being taken. Approx. 10 ml of the clear water phase was carefully pipetted off, then centrifuged to ensure that all of the organic phase had separated. The water phase was then manually extracted in order to determine the amount of remaining DCS.
• the invention may be applied to a wide variety of extractable components and solvents even if the examples mentioned earlier mainly discuss extraction of hydrophobic substances with organic solvents. It is e.g. possible to apply the invention for extracting inorganic substances, such as metal chelates, from water-based solutions. It is of course also possible to use the present invention for extraction with water from solvent based solutions.

Landscapes

• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Health & Medical Sciences (AREA)
• Biochemistry (AREA)
• Molecular Biology (AREA)
• Physics & Mathematics (AREA)
• Biomedical Technology (AREA)
• Analytical Chemistry (AREA)
• Engineering & Computer Science (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Extraction Or Liquid Replacement (AREA)
• Sampling And Sample Adjustment (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=8541586

Family Applications (1)

Country Status (3)

Families Citing this family (23)

Family Cites Families (3)

• 1994
  • 1994-10-14 FI FI944827A patent/FI100859B/fi active
• 1995
  • 1995-10-09 WO PCT/FI1995/000557 patent/WO1996012194A1/en not_active Application Discontinuation
  • 1995-10-09 EP EP95934155A patent/EP0786090A1/en not_active Withdrawn

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events