JP2004501756A - Water separation from solvent - Google Patents

Abstract

An apparatus (100) and method for separating residual water from a solvent. The apparatus comprises a container (102) for containing a solution containing a solvent containing residual water and having an opening through which the solution can be discharged. A film layer including a first layer (104) made of a fluoropolymer and a second layer (105) made of a fluoropolymer is provided. This membrane is continuously arranged at the opening of the container. When a vacuum occurs on one surface of the membrane layer, the solvent containing water passes through the membrane, and water is removed from the solvent to reduce the water content of the solvent to 1.0 ppm or less.

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to the field of chemical laboratory equipment for sample preparation, particularly to the use of hydrophobic membranes to separate water from organic solvents, and more particularly without adversely affecting membrane performance. Method and apparatus for increasing the flow rate of a solvent through a membrane.
[0002]
Problems to be solved by the prior art and the invention
If samples are to be analyzed for organic and / or inorganic trace compounds, they are typically extracted using an organic solvent. This solvent extracts the compound from the sample by selective chemistry.
[0003]
Before the extract is analyzed, any residual water should preferably be removed from the extraction solvent. This is because the residual water has a detrimental effect on the successive sample preparation steps required to prepare and analyze the sample.
[0004]
Current examples include the use of a desiccant called sodium sulfate, which was a standard technique for removing residual water from solvent extracts. Sodium sulfate is a granular material that has a large binding capacity for residual water. The sodium sulfate is first heated to remove any water adsorbed on the material. Heating usually requires heating at 400 ° C. overnight. The sodium sulfate is then placed in a glass funnel containing filter paper or a chromatography column. The funnel or column is then washed with an extraction solvent to wash away any impurities. The extraction solvent is then discarded. Once the sodium sulfate has been washed, the solvent extract is poured on top of the sodium sulfate. As the solvent drips slowly, the residual water becomes bound to the surface of the sodium sulfate. The drip and collected solvent is then dried and prepared for analysis.
[0005]
Sodium sulfate is easy to use, but requires many physical manipulations to use. Sodium sulphate requires the use of glassware that must be continuously washed to avoid contaminants on the sample, and requires purchase and disposal of spent sodium sulphate. Working time and material costs are a significant part of the total cost of performing sample extraction.
[0006]
U.S. Pat. No. 5,268,150, assigned to Corning, discloses a hydrophobic extraction system that allows the passage of solvents but not yet the passage of large amounts of water from sample liquids. The use of a membrane is disclosed. This patent teaches a hydrophobic solution incorporating polytetrafluoroethylene (PTFE) in order to achieve the desired result of passing the solvent while retaining a sample, which typically comprises a relatively large portion of water or an aqueous solution. It discloses that the membrane was found to be very effective. This patent discloses that typical membrane dimensions range from 10 millimeters to 50 millimeters in diameter, 0.1 microns to 5.0 microns in thickness, 0.2 microns to 5 microns, depending on the sample to be processed. It has a pore size in the range of 0.0 microns.
[0007]
It is therefore an object of the present invention to improve the arrangement described in the above patent documents and to provide a more efficient technique for separating water from a given solvent. More specifically, an object of the present invention is to improve the purification rate of a solvent / water mixture or emulsion through a membrane to remove water without adversely affecting the performance of the membrane. It is to provide a method and apparatus and an improved membrane configuration.
[0008]
[Means for Solving the Problems]
A method / apparatus for separating residual water from a solvent, comprising providing a container containing a solution containing a solvent containing residual water and having an opening through which the solution can be discharged, and a fluoropolymer screen. Passing the solution in the container through the fluoropolymer membrane supported on the substrate. The supported membrane is disposed continuously in the opening of the container and has a first surface in contact with the solvent and a second surface opposite thereto. To increase the flow rate of the solvent through the membrane layer, the pressure on the second face of the supported membrane layer is reduced relative to the first face of the supported membrane layer, and the fluoropolymer membrane is It functions to remove water from the solvent.
[0009]
The above and other objects, features and advantages of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings. In these figures, the same reference numerals indicate the same or similar parts.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Referring to the drawings, a first condensing / extracting device 100 is generally illustrated. The condensing / extracting apparatus 100 includes a column 102 and fluoropolymer material layers 104 and 105. Preferably, fluoropolymer layer 104 is affixed to fluoropolymer layer 105 to provide a film-type structure. The preferred fluoropolymer for layer 104 is PTFE, and the preferred fluoropolymer for layer 105 is ethylene chlorotrifluoroethylene (ECTFE).
[0011]
In addition to the base assembly 108 and the collection vessel 110, a screen support layer is shown at 106. Column 102 forms a container for holding a solvent. The column 102, which is pushed down to the top of the membrane (fluoropolymer layer 104 attached to fluoropolymer layer 105), may be used to hold the membrane in place. Column 102 can seal the membrane and prevent solvent from passing around the edge of the membrane. The column 102 and the collection vessel 110 are preferably formed from glass. Screen support membrane 106 is preferably an ECTFE or ETFE with an opening of 0.5-1.0 mm, a thickness of 0.5-1.0 mm, and a length of 0.25-0.50 mm. 1 is a fluoropolymer fabric screen.
[0012]
This membrane is preferably composed of layers 104, 105 characterized as follows:
Pore size: 0.05-0.2 microns;
Bubble point: one between 24.0 psi and 34.0 psi (47 mm membrane; isopropanol at 21 ° C.)
WEP: 50.0 psi minimum individual Gurley number: less than 30.0 seconds on average (100 cc air, 4.88 ″ water pressure drop through 1 inch square orifice)
Thickness: preferably 1.0 to 20 mils.
[0013]
The following provisions apply to the above:
Gurley number: Measurement of air leakage of fluoropolymer. The Gurley number is the time in seconds required for 100 cc of air to pass through a one inch square area of the membrane.
Bubble Point: The minimum pressure of ² units of KG / CM required to pass air through a fluoropolymer pre-wetted with water, isopropanol, or methanol.
Water inflow pressure (WEP): the pressure at which water passes through the membrane. This pressure is a visual analysis.
[0014]
In a preferred embodiment, the PTFE layer 104 has a suitable diameter in the range of 40-100 mm. The fluoropolymer layer 104 and the structural support film 105 are continuously arranged between the column 102 and the collection vessel 110. In the most preferred embodiment, a 3 mil thick PTFE layer 104 having a pore size of 0.1 micron is supported on a 10 mil thick nonwoven layer 105 of ECTFE polymer. The ECTFE polymer is preferably one obtained from Ausimont and sold under the name “HALAR” ™.
[0015]
In a preferred embodiment, a 3.0 mil layer of PTFE is applied to the 10 mil layer of ECTFE, and the application of the temperature setting results in a thin layer having a thickness of 3-7 mils. There is no value at all.
[0016]
According to the invention, the screen layer 106 is preferably an ethylene trifluoroethylene copolymer (ETFE). This screen layer helps the gaps or spaces between the laminar layers 104, 105 on the funnel surface and consequently creates a pressure differential across the cross-sectional area of the funnel surface to achieve more efficient performance. It can be distributed. However, it can be respected that the screen layer 106 is a separate component, but that the screen layer 106 may actually be incorporated directly into the surface of the funnel on which the laminar layers 104, 105 are placed. Can also be respected. This provides the same effect as spacing the laminar layers 104, 105 to evenly distribute the pressure differential created by the vacuum.
[0017]
Moreover, in the spirit of the present invention, water is efficiently removed from a given solvent containing several analytes to be evaluated by techniques such as, for example, gas / mass chromatography (GC / MS). Thus, it is understood that GC / MS analysis can be performed that is not compromised by the presence of water. In this regard, it can be seen that the present invention can remove water to a level of 1.0 ppm or less.
[0018]
Extending the above, the following is understood for water removal. In other words, GC / MS analysis that is not weakened by the presence of water is possible, which means that water removal here reduces water to a level at which impurities in the GC column can be removed or diluted by a water-soluble inorganic acid. It tells the fact that it is enough to make it happen. In addition, the possibility of any degradation of the GC column due to the presence of the water-soluble inorganic acid is also equally weakened or eliminated, and GC / MS can proceed without such problems.
[0019]
In addition, it is of no value that the present invention is preferably applied to water / solvent mixtures where the solvent is more concentrated than water. However, the present invention is not so limited, if interpreted broadly.
[0020]
As shown in FIG. 2, a second condensing / extracting device 200 is generally shown. The condensing / extracting apparatus 200 includes a column 202, a fluoropolymer layer 204 (PTFE), and a fluoropolymer layer 205 (ECTFE). As noted above, the fluoropolymer layers 204, 205 are preferably adhered to each other. In addition, a support screen membrane 206, a base assembly 208, and a collection vessel 210 are shown. Apparatus 200 may be connected to an external low-level vacuum chamber 216. The low-level vacuum chamber preferably produces a pressure drop of less than 6 ″ Hg. Alternatively, the assembly 200 includes a vacuum generator that uses a compressed gas supply to create a pressure differential. The assembly 200 is manufactured as a facility and is located directly at the bottom of the separating funnel in the hood, and once the gas supply is installed, the operator can select from among a plurality of vacuum levels on the vacuum level selection panel 214. One can be selected, the vacuum selection panel 214 controls the pressure drop across the membrane, these levels may include off, low, medium, and high, or the vacuum level is continuous Choose between different vacuum level types, as samples that produce important emulsions can be very easily destroyed if vacuum is not used. Once the emulsion has been broken, it can be set to increase the vacuum in order to significantly reduce the processing time of the sample, for example 10 ml of methylene chloride Passing through at 5 "Hg vacuum would take about 4 minutes. However, at 6 "Hg, passing the same sample using the same membrane would only take 15-20 seconds, which is a significant time saver.
[0021]
A controller 212 connected to the vacuum chamber 216 can be added that changes the pressure drop across the membrane over time. For example, the control device 212 may determine that a predetermined initial time during which a vacuum state is not established or a very low predetermined first vacuum level, a predetermined second time during which the predetermined vacuum level is increased and a predetermined second time. Can be programmed to have The controller 212 can also be programmed to stop the vacuum after a predetermined third time to prevent residual water from being drawn through the membrane. Given sufficient time, about 6-12 hours, any residual water on the surface of the membrane can "wet" the membrane and flow with the organic solvent. Therefore, there is a certain time period for water to stay on the membrane. However, this time is not a problem for the application in which the device is used.
[0022]
In addition, test results have shown that discharging the emulsion directly into the membrane container helps to break the emulsion. Once the emulsion is broken, the residual water and the emulsion can be poured back into the separating funnel after each drying step for further extraction, if desired by the analyst. This allows the recovery value to be increased as much as possible.
[0023]
As already mentioned, FIG. 3 is an exploded view of a preferred separation device according to the present invention. More specifically, as shown, locking ring 310, wave spring 312, thrust ring 314, container 316, base 318 for membrane, screen (not shown), cock 322, and shut-off connectors 324, 326. (It is evacuated via this connector) and the bracket 328 and support rod 330 can be seen.
[0024]
Although the invention has been described in detail herein, the invention may be other embodiments without departing from the spirit of the invention, and such other embodiments are defined in the claims. Should be understood to mean falling within the scope of the invention.
[0025]
[Cross-reference to related applications]
This application claims the benefit of corresponding US patent application Ser. No. 60 / 215,055, filed Jun. 29, 2000, the teachings of which are incorporated herein by reference. Have been.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a first separation device according to the present invention.
FIG. 2 is a sectional view of a second separation device according to the present invention.
FIG. 3 is an exploded view of a preferred separation device according to the present invention.
[Explanation of symbols]
100 container 104 first layer 105 second layer 106 film layer (film)
216 Vacuum chamber (device for generating vacuum state)

Claims (25)

A method of separating residual water from a solvent, comprising:
Providing a container containing a solution containing a solvent containing residual water and having an opening capable of discharging the solution,
Using a membrane layer comprising a first layer of a fluoropolymer and a second layer of a fluoropolymer and continuously disposed at the opening of the container to prevent the solution from flowing from the container. When,
Reducing the pressure on the second side of the supported membrane layer relative to the first side of the supported membrane layer to increase the flow rate of the solvent through the membrane layer. Prepare,
A method comprising removing the water from the solvent to obtain a solvent having a water content of 1.0 ppm or less. The method of claim 1, wherein
The method according to claim 1, wherein the first layer made of a fluoropolymer is made of PTFE. The method of claim 1, wherein
The method according to claim 1, wherein the second layer made of a fluoropolymer is made of ECTFE. 3. The method of claim 2, wherein
The method of claim 1, wherein said first layer of PTFE has a thickness of about 1-5 mils. 4. The method of claim 3, wherein
The method of claim 2, wherein said second layer of ECTFE has a thickness of about 5 to 15 mils. The method of claim 1, wherein
The method wherein the membrane layer has a Gurley number of 30.0 seconds or less and a pore size of 0.05 to 2.0 microns. The method of claim 1, wherein
The method wherein the membrane layer has a pore size of about 0.05-2.0 microns. The method of claim 1, wherein
Reducing the pressure on the second surface of the film layer relative to the first surface of the film layer by utilizing a vacuum. 9. The method of claim 8, wherein
Changing the vacuum state. 9. The method of claim 8, wherein
The method wherein the vacuum condition ranges from about 1 to 15 "Hg. 9. The method of claim 8, wherein
The method wherein the vacuum condition ranges from about 1 to 5 "Hg. The method of claim 1, wherein
The method of claim 1, further comprising postponing execution of the step of reducing pressure for a selected period of time. A method of separating residual water from a solvent, comprising:
Providing a container containing a solution containing a solvent containing residual water and having an opening capable of discharging the solution,
A first layer made of polytetrafluoroethylene (PTFE) and a second layer made of an ethylene chlorotrifluoroethylene (ECTFE) layer, the first layer being continuously disposed in an opening of the container, and the first layer being formed of the solvent. Preventing the solution from flowing from the container using a membrane layer in contact with
Reducing the pressure on the second side of the supported membrane layer relative to the first side of the supported membrane layer to increase the flow rate of the solvent through the membrane layer. A method comprising providing. The method of claim 13,
The method wherein the membrane layer itself has a Gurley number of 25.0 seconds or less and a pore size of 0.05 to 2.0 microns. The method of claim 14, wherein
The method wherein the pore size is about 0.1 microns. The method of claim 13,
The method of claim 1 wherein said PTFE layer is about 1-5 mils in thickness and said ECTFE layer is about 5-15 mils in thickness. The method of claim 13,
Reducing the pressure on the second surface of the film layer relative to the first surface of the film layer by utilizing a vacuum. The method of claim 17,
Changing the vacuum state. The method of claim 17,
The method wherein the vacuum condition ranges from about 1 to 15 "Hg. 20. The method of claim 19,
The method wherein the vacuum condition ranges from about 1 to 5 "Hg. The method of claim 1, wherein
The method of claim 1, further comprising postponing execution of the step of reducing pressure for a selected period of time. A method of separating residual water from a solvent, comprising:
Providing a container containing a solution containing a solvent containing residual water and having an opening capable of discharging the solution,
A first layer made of a fluoropolymer and a second layer made of a fluoropolymer, and arranged continuously in an opening of the container, and using a film layer supported by a screen layer, Preventing the solution from flowing;
Reducing the pressure on the second side of the supported membrane layer relative to the first side of the supported membrane layer to increase the flow rate of the solvent through the membrane layer. Prepare,
A method comprising removing the water from the solvent to reduce the water content of the solvent to 1.0 ppm or less. 23. The method of claim 22, wherein
The method according to claim 1, wherein the screen layer includes a fluoropolymer. 24. The method of claim 23,
The method according to claim 1, wherein the fluoropolymer comprises ETFE. An apparatus for separating residual water from a solvent,
A container containing a solution containing a solvent containing residual water and having an opening capable of discharging the solution,
A film layer including a first layer made of a fluoropolymer and a second layer made of a fluoropolymer, and continuously disposed at an opening of the container;
A device for generating a vacuum state on the second layer made of a fluoropolymer,
An apparatus, wherein the water containing solvent is passed through the membrane layer, whereby the water is removed from the solvent to reduce the water content of the solvent to 1.0 ppm or less.