MXPA00011911A - Inclusion methods for purifying a solvent - Google Patents

Abstract

Disclosed are methods for purifying solvents, by causing contaminants to be included within layers of dispersed exfoliated layered materials (transition metal dichalcogenides like tungsten disulphide), and then separating the restacked combined contaminant/layered material from the solvent. The methods may be utilized to remove materials suspended in the solvents, materials immiscible with the solvents, and are especially useful for separating soluble materials from the solvents within which they are dissolved. The application of these methods will be beneficial in the remediation of polluted soil and water, the desalination of water, waste oil and gray water purification, the preparation of pharmaceuticals, and many other areas.

Description

METHODS OF INCLUSION TO PURIFY A SOLVENT FIELD OF THE INVENTION The present invention relates essentially to the field of water purification. Methods for purifying solvents are published, causing contaminants to be included within layers placed in their site of dispersed stratified materials, and thus separating the combined contaminant / stratified material from the solvent. The methods can be used to remove materials suspended in solvents, materials immiscible with solvents, and are especially useful for separating soluble materials from the solvents within which they dissolve. The application of these methods will be beneficial in the remediation of oil and contaminated water, the desalination of water, waste oil and purification of gray water, the preparation of pharmaceutical preparations, and many other areas.

PREVIOUS TECHNIQUE There are many physical methods, whereby immiscible and / or suspended materials can be removed from a solvent. For example, the application of centrifugal force and various filtration techniques are common methods used to achieve these goals. There are also many known methods for separating solutes from solvents, within which they dissolve. Among these are anaerobic and aerobic biological purification, distillation processes, electrolysis, and various ion exchange and membrane filtration techniques. Although these methods are ideal for certain applications, they are ineffective, produce undesirable derivatives, or are prohibitive costs in others. Many coagulant, flocculation and precipitation techniques are also known, such as those described in U.S. Patent No. 5,330,658 to Grant et al. , and in Cárter, L.W. , and Knox, R.C. , Deborah Fairchild, Ground Water Quality Protection, Lewis Publishers, Inc. 1 987, p. 467-498. All these methods are relatively complicated and expensive. Although there are many examples where stratified materials such as carbon, zeolites, and others are used as impure absorbers, the properties of the laminated materials employed in the recent invention depend only on the surface qualities of the materials. Absorption or union is not required. It is well known that unmodified etratified materials such as transition metal dicalcogenides, column clays, and the like, dispersed in solutions, will trap amounts of water and other materials that also disperse in the solution when the layered materials disappear from the solution. suspension. For example, Miremadi went to. , in Patent of E.U. No. 5,328.61 8 discloses a method for producing a magnetic lubricant for retaining metal salts between layers of the laid laminates. However, if these unmodified laminates are used to purify solvents, economies are not advantageous. This is because the proportion of the amount of stratified material needed to remove a given amount of contaminants is high. Morrison I went to. , in the U.S. Patent. # 4,822,590 has published exfoliation methods, resulting in materials of simple molecular thickness, dispersed homogeneously and suspended in a solution. These materials are described as new single-layer materials of the MX (2) form, where MX (2) is a stratified-type dicalcogene such as MoS2, TaS2, Ws2, or the like. The method of exfoliation described is through the intercalation of the dicalcogene by an alkali metal and immersion in water or other protic solvents. It is clear that this process significantly reduces the size of the suspended particles of stratified materials. In this way, it produces a significant increase in the number of layers, within which other materials can be captured. This factor reduces the amounts of stratified materials needed to remove a given contaminant from a solvent. In this way, the economic factors included when these stratified materials are used to purify solvents are improved. U.S. Patent No. 4,853,359 to Morrison et al. , and the Patent of E. U. # 4,996, 1 08 for Divigalpitiya ei al. , as well as the inventors themselves during the patent applications of E. U. # 08/775873 and # 09/060189, describe unique new materials, which can be formed by coating, or include, materials selected from the layers of these exfoliated materials. Variously described in these publications are means to capture; particles suspended in a protic solvent, immiscible materials in protic solvents, and dissolved materials such as metal salts dissolved in water and metal hybrids dissolved in organic solvents, etc. However, the objects of all these inventions are the new materials created when the exfoliated materials are combined with recovered materials. of suspensions or solutions. None of these describes the benefits that can be achieved when these exfoliated materials are used to purify the solvents.

OBJECT OF THE INVENTION One of the main problems seen by industrial societies is the contamination caused by suspended, immiscible, or dissolved toxins in our water. Many of these contaminants can be removed at a relatively low cost by conventional physical means such as centrifugation or filtration. However, contaminants dissolved in water can not be removed by these methods and are very difficult to remove in a cost effective manner. Because they are energy intensive, or require relatively complex processes, known methods are particularly expensive when used to clean large amounts of water where dissolved contaminants may comprise only a few parts per million. It would be beneficial if the methods could be found relatively whereby small amounts of dissolved toxic materials could be removed from large quantities of water significantly in an effective way in cost. In many areas of the world's economic development is prevented because salts with great weight contaminate the only available water. Conventional desalination plants are expensive and require extensive infrastructure. It would often be beneficial if the desalination could be done by simpler and less expensive methods. In certain emergency situations such as tremors, floods, etc. , drinking water can be contaminated by a variety of suspended, immiscible, and dissolved materials. It could be beneficial in these cases if the low energy, low technology methods could be developed to remove all these materials from the water with a simple one-step process. In addition, many industrial and experimental processes, particularly in the semi-conductor and pharmaceutical food processing industries, require high purity solvents to eliminate the possibility of contamination of the desired product. What is needed is a simple, easy-to-operate method for purifying large volumes of solvents, especially water, that contain suspended, soluble, and insoluble contaminants, either simple or in combination, which effectively segregate the contaminants from the clean solvent and concentrate the material contaminated in a manageable, low volume, concentrated waste that inhibits the re-solubilization or suspension of contaminants.

SUMMARY OF THE INVENTION These and other needs are met by the invention, which is characterized by methods for substantially purifying contaminated protic solvents, and water miscible aprotic solvents, including combinations and mixtures thereof, said solvents being contaminated by suspended particles in solvents, materials dissolved in solvents, and / or solutions immiscible in solvents, comprised of means, applied simply or in combination, to disperse suspensions of materials laminated in said solvents in ways that cause contaminants to the mixture to be included between layers of stratified materials, and separate the material placed in its concentrated site with contaminants included from the purified solvent. These inclusion methods for purifying solvents are most effective where the pH of the solvent is high enough to inhibit the immediate flocculation of the stratified material. In addition, the suspension of the stratified material must be combined with the solvent in a manner that will effectively include the contaminants. Therefore, the methods of the present invention are also comprised of means for adjusting the pH of the solvent and also means for effectively mixing the suspensions of layered materials with said contaminated solvents. The inclusion of the contaminants within the layers of the dispersed stratified material causes the combined stratified / contaminant material to be concentrated and placed in its place in any of the, or both, lower part and upper part of the mixing container. In this way, the remaining solvent is purified. Therefore, the present invention is also comprised of means for separating the purified solvent from the material placed in its concentrated site. In the context of this publication, protic solvents refer to solvents that donate hydrogen, such as water, alcohol, ethanol, and the like. Water-miscible aprotic solvents refer to polar solvents, which do not give hydrogen and do not form separate layers when mixed with water, such as tetrahydrofuran, dimethylformamide, and the like. Said stratified materials are preferably exfoliated stratified materials which can be exfoliated by known methods, for example by first intercalating with an alkali metal and then exfoliating by immersion in a protic solvent. The preferred exfoliated materials are exfoliated transition metal dicalcogens of the MX2 form, where M is selected from the group Mo, W, Ta, Nb, Va, and X is Sulfur or Selenium. It is also preferred that the exfoliated materials be suspended in solvents.

Although the inventor does not wish to be bound by any particular theory, it is known that the exfoliation process causes the simple molecular particles of stratified materials to be separated by amounts of solvent. In this way, the number of layers within which the materials can be captured increases greatly. This capture, or inclusion, of the solvent between the layers is the crucial factor that keeps the particles of the stratified materials separated from other stratified particles in the suspension. It is apparent that if the inclusion of solvent is pure, the suspended exfoliated materials remain in suspension, and resist! be established even when subjected to sustained applications of centrifugal force. However, if the solvent is impure, it is believed that the impurities are also included with the solvent, between the layers of exfoliated material and that their combined specific gravity, or immiscibility causes the particles in suspension to segregate. Exfoliated materials with inclusions of impure solvent either settle quickly on the bottom or rise to the top, while the exfoliated materials with inclusions of pure solvent tend to remain in the intermediate part. When the exfoliated materials are established, they believe they are separated by a bi-molecular layer of tenacious relativity of the solvent. Any suspended solute or pollutant will also be included. Where the contaminant is immiscible, the exfoliated material includes both the miscible and immiscible materials and is collected at the interface of the two liquids.

In addition, although it is not necessary for the exfoliated materials to form simple molecular layers in suspension, it is preferred that those suspensions contain a portion of simple molecular layer materials. In the context of this publication the simple molecular materials in suspension are defined as individual molecules of suspended stratified material separated from any other molecule of stratified material suspended by at least one molecule of solvent. Example 1: A sample of water contaminated reportedly removed from a ship bilge and containing a variety of organic materials, detergents, and dissolved metals was obtained from Comprehensive Water Management Inc., of Delta, British Columbia. During the inspection of the sample, it was noted that the liquid had a dark brownish color with a strong smell usually associated with organic material, the particulate matter could be clearly observed in suspension, and that when shaking a persistent foam it forms in the air for the interface. of liquid. An analysis was presented in an amount of the sample, using ICP, to determine the level of dissolved metals in the sample. Two grams of how MoS2 is received supplied by Aldrich Chemicals with a reported purity of 99.5% was added to the sample and stirred vigorously then mixed continuously for half an hour at medium speed with a magnetic stirrer. When the stirrer is removed the MoS2 is quickly established in the lower part of the container. The liquid was slightly lighter in color. The liquid was decanted and a portion removed by ICP analysis to determine the level of dissolved metals remaining in the sample. The results are summarized in Table I. Table I ANALYTICAL REPORT Boron contaminated wastewater (BTEX) pH7 Minimum detectable quantity Quantity (PPM) Ca ntity (PPM) (PPM) Before treatment After treatment Dissolved arsenic 0.04 2.43 1 .17 Dissolved boron 0.008 1 57 109 Dissolved calcium 0.01 803 591 Dissolved magnesium 0.02 639 525 Dissolved phosphorus 0.04 259 166 Dissolved potassium 0.4 682 556 Dissolved sodium 0.01 61 90 5290 Dissolved strontium 0.001 2.28 1 .72 Dissolved thallium 0.02 0.13 < 0.02 Dissolved zinc 0.002 24.4 6.22 This clearly demonstrates that stratified materials can be used to remove dissolved impurities from water. Example 2 A suspension containing two grams of exfoliated MoS2 was added to the same amount of the contaminated bilge water sample as in the previous example. The sample was vigorously stirred and mixed in a similar manner. Suspended MoS2 is established more slowly and in addition, a layer of exfoliated material is formed in the air for the water interface. The liquid in the center was significantly lighter in color. A sample of the center liquid was extracted by pipette and analyzed by ICP for dissolved metals. The results are summarized in Table 2. Table 2 ANALYTICAL REPORT Boron contaminated wastewater (BTEX) pH7 Minimum detectable quantity Quantity (PPM) Quantity (PPM) (PPM) Before treatment After treatment Dissolved arsenic 0.04 2.43 0.29 Dissolved boron 0.008 157 25.4 Dissolved calcium 0.01 803 1 14 Dissolved magnesium 0.02 639 109 Dissolved phosphorus 0.04 259 40.2 Dissolved potassium 0.4 682 1 13 Dissolved sodium 0.01 6190 1 130 Dissolved strontium 0.001 2.28 0.283 Dissolved thallium 0.02 0.13 0.04 Dissolved zinc 0.002 24.4 1 .26 This clearly demonstrates that stratified exfoliated materials are more effective than non-exfoliated materials in the removal of dissolved metals from water.

At approximately pH2 the exfoliated material agglomerates and the material becomes less effective at removing impurities. At pH levels above about 9, the exfoliated materials tend to remain in suspension for longer periods. The pH of the solvent can either be adjusted by adding a suitable conditioner before the addition of the layered material, or the pH of the stratified material suspension can be adjusted in such a way that when added to the solvent it will be neutralized. Example 3: A sample of drainage from the acid waters of the mines, pH3, was reportedly collected by the British Columbia, Ministry of Mines from a site known as the Britannia mimas was analyzed by standard methods using ICP to determine the quantities of metals dissolved in the liquid. The pH of the mine drainage was brought to neutral by the addition of a quantity of lithium hydroxide. A neutral suspension of the exfoliated material was also prepared. Prepared suspensions were added in stages to an amount of drainage from the acid waters of the mines. After each addition of the suspension to the drainage of the acid waters of the mines, the combined liquids were mixed through a magnetic stirrer. When the agitator was removed, the suspension became clear, and an agglomeration of black material was quickly established in the lower part of the container. The clear liquid was decanted and a second analysis was conducted. The analytical results for selecting selected pollutants are shown below in Table 3. Table 3 ANALYTICAL REPORT Drainage of contaminated mine waters (Britannia) Minimum detectable quantity C ity (PPM) Car ity (PPM) (PPM) Before treatment After treatment Dissolved calcium 0.01 378.0 0.06 Dissolved copper 0.001 10.0 0.006 Dissolved lead 0.02 0.04 < 0.02 Dissolved manganese 0.002 3.67 < 0.002 Dissolved Magnesium 0.02 60.5 0.1 54 Dissolved Strontium 0.001 2.07 < 0.001 Dissolved zinc 0.002 24.1 0.008 These results clearly demonstrate that the addition of pH modifiers to solutions will not inhibit the ability of suspensions of exfoliated materials to remove dissolved metals from solutions. The methods required to efficiently mix the layered materials with the solvents depend greatly on the type of materials to be removed. The agitation or application of methods, which causes the suspension of stratified materials are in a counterflow with the contaminated solvents, which is apparently effective to capture the majority of dissolved metals. However, in order to capture materials with a specific gravity significantly lower than the solvent, or which are immiscible in the solvent, more active forms of agitation such as stirring or bubbling must be employed to form an emulsion. Example 4: An exfoliated WS2 sample was prepared by known methods to produce a mixture of multi-layer and single-suspension particles. This sample was centrifuged for approximately 1.5 minutes at 3000 rpm and a black paste containing single and multi-stratified materials was recovered, separated by layers of trapped water. The exfoliated material / waste pulp was mixed, by agitation, at water levels with the contaminated sample. The same agglomeration process reported in Example 1 occurred. The brown color of the liquid changed to pale yellow. Nevertheless, a point was reached in the addition of the exfoliated material where the color change did not occur so quickly. At this point the sample was vigorously agitated. A foam emulsion was created in the air for the water interface. As new material was added and the agitation continued, the frothy was significantly reduced in quantity and persistence. When it was left to establish, a clear delineation of materials occurred. Some of the black exfoliated materials formed a layer in the air for the water interface, and some settled in the bottom of the container. The color of the liquid in the middle part changed rapidly from pale yellow to transparent and colorless. Upon noticing the removal of the liquid color the addition of the exfoliated material stopped. It is believed that the layer on the top of the exfoliated material is contained with inclusions of organic material and phosphates. The material that is established in the lower part is believed to have contained dissolved metals and previously suspended particulate matter. The clear liquid of the intermediate layer was removed. It was colorless, had a delicate smell of alcohol, and produced a light foam, easily dispersed, in agitation. This liquid sample was analyzed using ICP to select dissolved metals. The results are described in Table 4. Table 4 ANALYTICAL REPORT Organic polluted wastewater and Molybdenum &; Boron (BTEX) pH7 Minimum detectable quantity Quantity (PPM) Quantity (PPM) (PPM) Before treatment After treatment Dissolved arsenic 0.04 0.32 < 0.4 Dissolved boron 0.008 157 25.4 Dissolved molybdenum 0.004 5.16 0.199 Dissolved phosphorus 0.04 259 40.2 Dissolved zinc 0.002 24.4 1 .26 These results clearly demonstrate that the dissolved, suspended, immiscible materials were removed from the solvent by the addition of the exfoliated material. It is also evident that not all exfoliated materials need to be single layer.

In addition, active agitation such as stirring or bubbling in some manner such that an emulsion is formed, is more effective at removing certain contaminants than simply stirring. Finally, aprotic miscible solvents can also be purified in this manner. Example 5 Magnesium hydride was dissolved in tetrahydrofuran by known methods. The resulting solution was a deep red color. A suspension of MoS2 exfoliated in tetrafuran was added dropwise to the hydride solution. The dissolved magnesium was quickly captured as inclusion within layers of exfoliated material and settled out of solution forming a black cake in the lower part of the sample container. The color of the remaining liquid was a clear with a pale orange tint and consisted substantially of pure tetrahydrofuran. It will be understood by one skilled in the art that many of the details provided above are by way of example only and may be varied or omitted without departing from the scope of the invention, which is construed with reference to the following claims.

Claims (10)

1. CLAIMS 1. A method for purifying a contaminated solvent, said solvent contaminated by particles suspended in said solvent, and / or materials dissolved in, and / or immiscible solutions in said solvent, comprises the steps of: (a) dispersing a suspension of stratified exfoliated material in said solvent; (b) mixing said suspension in said solvent to cause contaminants in said solvent to be included among the layers of said exfoliated laminate material; and (c) separating a concentrate from said stratified material placed in its place trapping said contaminants as inclusions of said solvent.
2. 2. The method according to claim 1, further comprising an initial step of suspending said stratified material exfoliated in a solvent to form said suspension.
3. 3. The method according to claim 1, further comprising an initial step of suspending said stratified material exfoliated in a solvent, characterized in that said exfoliated stratified material is exfoliated transition metal dicalcogen.
4. 4. The method according to claim 1, further comprising the step of adjusting the pH of said solvent.
5. 5. The method according to claim 1, further comprising the step of adjusting the pH of said suspension.
6. 6. The method according to claim 1, characterized in that said step of dispensing said suspension in said solvent includes the step of mixing said solvent and said suspension together. The method according to claim 1, characterized in that said step of mixing said suspension in said solvent comprises causing said solution and said suspension to flow together in such a way that a direction of flow of said suspension is contrary to a flow direction of said solution. The method according to claim 1, characterized in that said step of mixing said suspension in said solvent comprises stirring said solution and said suspension together. The method according to claim 1, characterized in that said step of mixing said suspension in said solvent comprises creating an emulsion of said solution and said suspension. The method according to claim 1, characterized in that said step of separating a concentrate from said stratified material placed in its place of said solvent comprises decanting said solvent. eleven . The method according to claim 1, characterized in that said step of separating a concentrate from said stratified material placed in its place of said solvent comprises applying centrifugal force to separate said solvent from said stratified material placed in its place and decanting said solvent. The method according to claim 1, characterized in that said step of separating a concentrate from said stratified material placed in its place of said solvent comprises by extraction said solvent. 3. A purification method for purifying a contaminated solvent without absorption or chemical bonding of contaminants in said contaminated solvent, comprising the steps of: (a) suspending the exfoliated transition metal dicalcogens of the MX2 form, characterized in that M is selected from the group of Mo, W, Ta, Nb, Va, and where X is S or Se, in suspension; (b) vigorously mixing said suspension with said contaminated solvent; (c) maintaining said pH of said solvent and said suspension within an optional pH range to inhibit immediate flocculation and optimally placing said exfoliated transition metal dicalcogens suspended in said suspension; (d) allowing said exfoliated transition metal dicalcogenides placed in place and flocculated to join as a concentrate; (e) separating said concentrate from said solvent.