HK1097793B - Purification of fluids with nanomaterials - Google Patents

Description

Purification of fluids using nanomaterials

The national priority rights of this patent for united states provisional patent application No. 60/452,530, filed on 7/3/2003, united states provisional patent application No. 60/468,109, filed on 6/5/2003, and united states provisional patent application No. 60/499,375, filed on 3/9/2003, are all incorporated herein by reference in their entirety.

Technical Field

The present disclosure relates to a nanostructured material comprising defective carbon nanotubes selected from the group consisting of impregnated, functionalized, doped, charged, coated and irradiated nanotubes. The present disclosure also relates to the use of the nanostructured materials for the purification of fluids such as liquids and gases. The disclosure also relates to purifying water using the nanostructured materials.

Background

There are many procedures and methods for processing fluids for consumption, use, disposal, and other needs. Among the most popular processes, pasteurization is used to sterilize food, chemical treatment is used to sterilize water, distillation is used to purify liquids, centrifugation and filtration are used to remove particulates, decantation is used to separate two phases of fluid, reverse osmosis is used for liquid desalination, electrodialysis is used for liquid desalination and catalytic processes are used to convert unwanted reactants into useful products. Each of these methods is well suited for a particular application, and thus combinations of methods are typically used in the final product.

One development prospect for nanotechnology materials is that they will help things to be done more economically than their traditional counterparts. In the field of liquid purification, any technique that reduces the overall cost, simplifies the process and improves efficiency would be highly advantageous.

Many of these methods will be improved by using nanomaterial purification techniques. Nanoporous materials would be suitable for removing microorganisms, micron-sized particles and other fine materials. Reverse osmosis membranes made with nanomaterials can help to promote the flow of water through the membrane. Incorporating robust nanomaterials into any of the above methods will reduce the weight of all these components. However, two approaches appear to be particularly possible for nanomaterial fluid purification: disinfection and desalination.

Method of disinfection

Many different techniques are available for liquid disinfection. Adsorption, chemical treatment, ozone disinfection and UV radiation all work well to remove pathogenic microorganisms. However, each of these techniques has its limitations, including overall efficacy, starting and operating costs, byproduct risks, necessary liquid pretreatment, toxic compounds used or generated, and other limitations.

Although the chemical method is most widely used, it has many disadvantages. Such disadvantages include increased adaptation of the microorganism to its destructive effects (e.g. cryptosporidium (cryptosporidium parvum)), safety hazards associated with the use of chlorine and storage, and environmental impact. UV is commonly used, but in order for it to be more effective the liquid must be clear, UV does not disrupt any biofilm formation, and is very expensive to install and operate.

In industrial and municipal applications such as water and wastewater plants, the three most widely used methods of liquid disinfection are: ozone, chlorine and ultraviolet radiation. Recent announcements by the U.S. environmental protection agency have identified advantages and disadvantages of each approach.

Ozone is more effective than chlorine in destroying viruses and bacteria, has a shorter effective contact time (10-30 minutes), leaves no harmful residues when it is rapidly decomposed, and is generated on site, thus having no transportation risk. On the other hand, low doses of ozone may be ineffective, more complex than UV or chlorine, highly reactive and corrosive, toxic, capital cost high and power demanding.

Chlorine is more economical than ozone or UV, its residues can prolong disinfection, it is reliable and effective against a range of pathogenic organisms, and it provides flexible feed control. Nevertheless, chlorine still carries significant risks, including the fact that: chlorine residues are toxic to aquatic organisms, chlorine is corrosive and toxic, oxychlorination of organic matter produces harmful compounds, and certain parasites have shown resistance. In addition, chlorine can combine with natural organic materials to produce carcinogenic compounds that are harmful to drinking.

Ultraviolet radiation has been used for quite a long time because it effectively inactivates most spores, viruses and cysts, eliminates the handling risk of chemicals, leaves no harmful residues, is easy to handle for use by operators, requires a very short effective contact time (20-30 seconds) and requires only little space. Disadvantages of UV radiation include: may be ineffective at low doses; organisms can sometimes reverse and repair UV damage; the tubes can become clogged, requiring frequent preventative maintenance; turbidity can cause UV inefficiency and power requirements are high. Furthermore, hazardous UV lamps are expensive to handle.

In response to the deficiencies of the known sterilization methods, many new methods have been tried. For example, U.S. patent No. 6,514,413, which is incorporated herein by reference, discloses the use of a composite germicidal adsorbent material. However, the bactericidal adsorbent material has been shown to be susceptible to biological fouling and complete growth of continuously reproducing bacteria. U.S. patent application No. 09/907,092 discloses a portable oxidant generator that produces chlorine or chlorine-oxygen solutions for disinfecting contaminated drinking water. U.S. patent No. 6,495,052 discloses a system and method for treating water by introducing a biocide into the water and then removing the biocide prior to drinking. United states patent application No. 10/029,444 discloses a method in which water is subjected to light from a laser as a means of disinfection.

However, these methods again rely on high electrical power input, toxic chemicals, or long effective contact times. There remains a need for a method that has minimal energy requirements, utilizes non-toxic chemicals, requires only a short contact time, and can be embodied in a portable device.

Desalination process

Liquid desalination is very useful for drinking water, biological fluids, pharmaceuticals, chemicals, petroleum and its derivatives, and many other liquids. Furthermore, water desalination is beneficial because less than 0.5% of water on earth can be directly suitable for human drinking, agriculture, or industrial use. Thus, worldwide, desalination is found to be increasingly advantageous for producing drinking water from brackish groundwater and seawater, as it makes about another 99.5% of the water potable.

It is estimated that there are 4,000 water desalination plants worldwide with combined production capacities of over 3,500 megagallons (mgd) per day. About 55% of this capacity is in the middle east and 17% in the united states, most of which are for industrial use. Desalinated water currently accounts for about 1.4% of the water consumed in the united states for domestic and industrial purposes.

There are generally five basic desalination methods: thermal methods, reverse osmosis methods, electrodialysis methods, ion exchange methods and freezing methods. The thermal and freezing processes remove fresh water from the brine, leaving behind a strong brine. The reverse osmosis method and the electrodialysis method separate salt from fresh water using a membrane. Ion exchange processes involve passing brine through a resin to exchange unwanted dissolved ions for more desirable ions. Currently only the thermal and reverse osmosis processes are commercially viable.

Us patent nos. 5,217,581 and 6,299,735, which are incorporated herein by reference, describe thermal processes involving boiling or evaporating brine and condensing the vapor into fresh water, leaving a more concentrated brine solution. Compared to other processes, the energy requirements of desalination processes are relatively high. Desalination is widely used in the middle east for treating seawater, in part because the energy required does not increase significantly with increasing salinity of the feed water.

As described in us patent No. 3,462,362, the reverse osmosis process is a membrane process that takes advantage of the tendency of fresh water to pass through a semi-permeable membrane into a salt solution, thereby diluting the more concentrated brine. Fresh water passes through the membrane as if there were pressure on it, which is called osmotic pressure. By applying very high pressure to the brine on one side of the semi-permeable membrane, fresh water can be forced through the membrane in the opposite direction to the permeate flow. This method is called reverse osmosis. Although reverse osmosis requires a relatively high amount of energy (to generate high pressure), its energy requirement is generally lower than that of distillation, although it is less efficient than other methods using feed water. In addition, membranes are very expensive, delicate and prone to clogging.

Electrodialysis desalination is a membrane process that removes contaminants and salts from liquids by using an electric current to push ionic impurities through an ion selective membrane and out of the treated liquid. Two types of ion selective membranes are used-one that allows positive ions to pass through and one that allows negative ions to pass between electrodes in the electrolytic cell. An electric force is used to overcome the resistance of the ions to pass through the ion selective membrane. The greater the drag, the greater the power demand, and thus the energy cost will increase with increasing drag. When a current is applied to drive the ions, a thin liquid remains between the membranes. The amount of electricity required for the electrodialysis process increases with increasing salinity of the feed solution and, therefore, the operating cost thereof increases.

Ion exchange resins replace hydrogen and hydroxide ions with salt ions. Many municipalities use ion exchange processes to soften water and the industry typically uses ion exchange resins as a final treatment after reverse osmosis or electrodialysis to produce very pure water. The major cost of ion exchange processes is maintenance or replacement of the resin. The higher the concentration of dissolved salts in water, the more frequent the resin needs to be regenerated, so ion exchange processes are rarely used for large scale salt removal.

The freezing method comprises three stages: partially freezing the brine to produce fresh water ice crystals therein; separating the ice crystals from the brine; the ice crystals are then melted (e.g., U.S. patent No. 4,199,961). The freezing process has certain advantages over other processes because it requires only lower energy and its low operating temperature minimizes corrosion and fouling problems. The energy requirements of the freezing process are high and generally comparable to the reverse osmosis process. Freezing technology is still under exploration and development and is not widely deployed. Freezing technology is not a compatible technology for portable desalination devices.

Many capacitors have been invented for desalination purposes. Us patent No. 4,948,514 discloses a method and apparatus for separating ions from a liquid. U.S. patent No. 5,192,432 discloses a similar "flow-through capacitor" method for separating ions from liquids. But these devices have not found large scale use because they are not commercially viable.

Disclosure of Invention

The present disclosure relates to a method for fluid purification based on nanotechnology materials, solving the above mentioned problems. One aspect of the present disclosure relates to a nanostructured material comprising defective carbon nanotubes selected from the group consisting of impregnated, functionalized, doped, charged, coated, and irradiated nanotubes. "nanostructure" refers to a structure having nanometer dimensions (e.g., parts per billion meters), such as at the atomic or molecular level. A "nanostructured material" is a material that comprises at least one of the aforementioned carbon nanotube components. A "nanomembrane" is a film composed of nanostructured materials. Defective carbon nanotubes are those that contain a lattice distortion in at least one carbon ring. Lattice distortion means any distortion of the atomic lattice of the carbon nanotubes forming the tubular sheet structure. Non-limiting examples include due to inelastic deformation, or the presence of 5 and/or 7 membered carbocyclic rings, or chemical interactions and subsequent bonding of carbon atoms sp²Any atomic shift due to a change in hybridization.

Another aspect of the present disclosure relates to elongated carbon nanotubes consisting essentially of carbon, wherein the nanotubes are distorted by crystal defects, similar to the case described above. In this example, the nanotubes are distorted by defects to the following extent: such that when the nanotubes are treated they are significantly more chemically active, allowing the nanotubes to react or bond with chemicals that would not otherwise react or bond with undistorted and/or untreated nanotubes.

In one aspect of the invention, the carbon nanotubes are present in the nanostructured material in an amount sufficient to substantially destroy, alter, remove or separate contaminants in a fluid in contact with the nanostructured material. The carbon nanotubes are treated to achieve the properties. For example, chemically treating the carbon nanotubes may result in the resulting nanotubes having at least one at least partially open end. Nanotubes having such ends may provide unique properties from a fluid flow perspective or from a functionalization perspective, for example, such that the ability of the ends may be specifically functionalized.

In another aspect of the invention, the material used to impregnate, functionalize, dope, or coat the carbon nanotubes is present in an amount sufficient to actively and/or selectively transport the fluid or a component thereof into, out of, through, along, or around the carbon nanotubes. Such materials may comprise the same materials that are selectively transported into, out of, through, along, or around the carbon nanotubes.

For example, the nanostructured material used to remove arsenic from the fluid may be first impregnated with arsenic ions. These arsenic ions are referred to as "target ions". The "target ions" typically comprise the same ions that are impregnated (functionalized, doped, or coated) into the carbon nanotubes and that are the contaminant ions found in the fluid to be purified or purified.

As used herein, "impregnated" means that the carbon nanotubes are at least partially filled with the relevant material as shown above, which may include the same ions of the contaminant to be removed from the contaminated fluid. By impregnating the target ions into the carbon nanotubes, the nanotubes and indeed the nanostructures made from the nanotubes are packed or "excited" to accept and/or attract those same ions found in the contaminated fluid.

Although the above examples refer to impregnating ions, the same methods are applicable to exciting or charging carbon nanotubes with desired ions by any of the procedures (e.g., functionalization, doping, coating, and combinations thereof). Doped carbon nanotubes refer to the presence of atoms other than carbon in the nanostructure material.

With respect to impregnation, an ion-specific separation device composed of target ion-impregnated carbon nanotubes can be manufactured. With this device, the impregnated nanotubes are fabricated such that electron or phonon flow can be induced by electromagnetic or acoustic means or by direct electrical or physical connections, and have defect sites that can be chemically opened by functionalization to create ion channels.

During excitation of carbon nanotubes by at least partially filling the carbon nanotubes with target contaminating ions, ion-specific quantum wells will be created in the hollow regions of the nanotubes due to the quasi-one-dimensional nature defined by the morphology of the carbon nanotubes. This will create a "pre-designed" or ion specific trap as ions move or flow through the nanotube. As ions move within the nanotube, ion-specific traps remain in the quasi-one-dimensional quantum structure of the nanotube.

When the ion-contaminated fluid is contacted with the treated "pre-engineered" nanostructure material containing the target ions, the target ions will be able to minimize their free energy by adsorbing and filling the ion-specific traps in the nanotubes. The addition of the target ion to the nanotube will cause a change in resistance that will elicit an electrical and/or acoustic current response, thereby moving at least one ion through the nanotube and out of the system. The material may be designed or redesigned depending on the ions that the nanostructured device nanotubes are filled with.

When the ion concentration changes, the device will not need to consume power, as power is only needed when the target ions are present. The built-in self-limiting method will take advantage of the fact that no power is required to remove target ions when they are not present in the fluid.

Depending on the contaminants to be removed from the contaminated fluid, the target material or the material used to impregnate, functionalize, dope or coat the carbon nanotubes may comprise at least one compound selected from the group consisting of oxygen, hydrogen, ionic compounds, halogenated compounds, sugars, alcohols, peptides, amino acids, RNA, DNA, endotoxins, metal organic compounds, oxides, borides, carbides, nitrides and elemental metals and alloys thereof.

The oxides include any well-known oxide commonly used in the art, such as oxides of carbon, sulfur, nitrogen, chlorine, iron, magnesium, silicon, zinc, titanium, or aluminum.

In one aspect, the nanostructured material comprises carbon nanotubes disposed in, and optionally dispersed by sonication in, a liquid, solid or gaseous medium. The carbon nanotubes may be maintained in the medium by mechanical force or a field selected from mechanical, chemical, electromagnetic, acoustic and optical fields or combinations thereof. Those skilled in the art will understand that the acoustic field includes a particular frequency of noise in the cavity to form a standing wave that maintains the carbon nanotubes in a substantially static position.

Similarly, the optical field may comprise a single or active array of optical tweezers generated by a laser through a hologram.

The solid medium in which the carbon nanotubes are typically found comprises at least one component selected from the group consisting of fibers, matrices, and particles, each of which may comprise a metal, ceramic, and/or polymeric material. In solid media, carbon nanotubes are interconnected and/or connected to fibers, matrices, and particles (such as particles up to 100 microns in diameter) to form nanomembranes.

The particle size is determined by the number distribution, e.g. the number of particles with a specific size. The methods are typically measured using microscopic techniques, such as with calibrated optical microscopes, calibrated polystyrene beads, and calibrated scanning force microscopes or scanning electron microscopes or scanning tunneling microscopes and scanning electron microscopes. In Walter C.McCrone et alThe Particle Atlas(encyclopedia of particle recognition technology), volume I, Principles and Techniques, second edition (Ann Arbor Science Pub.), which is incorporated herein by reference, teaches methods for measuring particles of the sizes described herein.

In various aspects of the invention, the polymeric material of the solid medium comprises a single or multi-component polymer (advantageously wherein the multi-component polymer has at least two different glass transition temperatures or melting temperatures), nylon, polyurethane, acrylics, methacrylics, polycarbonates, epoxies, silicone rubbers, natural rubbers, synthetic rubbers, vulcanized rubbers, polystyrene, polyethylene terephthalate, polybutylene terephthalate, Nomex (poly-m-phenylene isophthalamide), Kevlar (poly-p-phenylene terephthalamide), PEEK (poly-ether-ketone), Mylar (polyethylene terephthalate), viton (viton) (viton fluoroelastomers), polytetrafluoroethylene, halogenated polymers such as polyvinyl chloride (PVC), polyester (polyethylene terephthalate), polypropylene, and polychloroprene.

At least two different glass transition temperatures or melting temperatures of the multi-component polymers described herein are measured by heating the material to a temperature that has inelastic deformation.

In one aspect of the invention, the ceramic material of the solid medium comprises at least one of the following: boron carbide, boron nitride, boron oxide, boron phosphate, compounds having a spinel or garnet structure, lanthanum fluoride, calcium fluoride, silicon carbide, carbon and its allotropes, silicon oxide, glass, quartz, alumina, aluminum nitride, zirconia, zirconium carbide, zirconium boride, zirconium nitrite, hafnium boride, thorium oxide, yttrium oxide, magnesium oxide, phosphorus oxide, cordierite, mullite, silicon nitride, ferrite, sapphire, steatite, titanium carbide, titanium nitride, titanium boride and combinations thereof.

In another aspect of the invention, the metallic material of the solid medium comprises at least one of the following elements: aluminum, copper, cobalt, gold, platinum, silicon, titanium, rhodium, indium, iron, palladium, germanium, tin, lead, tungsten, niobium, molybdenum, nickel, silver, zirconium, yttrium, and alloys thereof (including iron alloys, i.e., steel).

Liquid media in which carbon nanotubes may be found include water, oils, organic and inorganic solvents, and liquid forms of nitrogen and carbon dioxide.

The gaseous medium in which the carbon nanotubes may be found includes air or a gas selected from the group consisting of argon, nitrogen, helium, ammonia and carbon dioxide.

One aspect of the present disclosure relates to the use of carbon nanotubes having a coiled tubular or non-tubular carbocyclic nanostructure. These carbon nanotubes are typically single-walled, multi-walled, or a combination thereof, and may take various morphologies. For example, the carbon nanotubes used in the present disclosure may have a morphology selected from nanohorns, nanospirals, dendrites, trees, star nanotube structures, nanotube Y-junctions, and bamboo-like morphologies. The shape generally helps to increase the use of the carbon nanotubes for nanofilms. The above shapes are more specifically defined in m.s. Dresselhaus, g. Carbon Nanotubes: synthesis, Structure, Properties, and Applications, Topics in Applied Physics, Vol.80, 2000, Springer-Verlag; and "A Chemical Route to Carbon nanoscols, Lisa M.Viculis, Julia J.Mack and Richard B.Kaner; science 28February 2003; 299, both of which are incorporated herein by reference.

As previously described, carbon nanotubes can be functionalized to achieve a desired chemical or biological activity. Functionalized carbon nanotubes, as used herein, are carbon nanotubes comprising inorganic and/or organic compounds attached to their surface.

The organic compound may comprise linear or branched, saturated or unsaturated groups. Non-limiting examples of the organic compound include at least one chemical group selected from the group consisting of: carboxyl, amine, polyamide, polyamphiphilic molecules, diazonium salts, pyrenyl, silane, and combinations thereof.

Non-limiting examples of inorganic compounds include at least one fluorine compound of boron, titanium, niobium, tungsten, and combinations thereof. The inorganic compound as well as the organic compound may contain a halogen atom or a halogenated compound.

In one aspect of the invention, the functionalized carbon nanotubes comprise any one or any combination of the above inorganic and organic groups. These groups are typically located at the ends of the carbon nanotubes and are optionally polymerized.

For example, functionalized carbon nanotubes can comprise inhomogeneities in the composition and/or density of functional groups across the surface of the carbon nanotube and/or across at least one dimension of the nanostructured material. Similarly, the functionalized carbon nanotubes can comprise a substantially uniform gradient of functional groups across the surface of the carbon nanotubes and/or across at least one dimension of the nanostructured material.

According to one aspect of the present disclosure, the carbon nanotubes are charged, such as with an AC or DC electromagnetic field, to a level sufficient to achieve the desired properties. Desirable properties include facilitating surface coating of the nanotubes or assisting in the destruction, alteration, removal, or separation of contaminants found in fluids in contact with or in proximity to the carbon nanotubes. "remove" is understood to mean at least one of the following mechanisms: size exclusion, absorption and adsorption.

Further, the charging may be performed using any of the following methods: chemical, radiation, capacitive charging, or fluid flows adjacent to and/or through the carbon nanotubes. The charging of the nanotubes may be performed prior to or simultaneously with the above-described functionalization procedure.

The charging of the nanotubes helps to facilitate coating of the carbon nanotubes with metallic and/or polymeric materials. Examples of the metallic material that can be used to coat the carbon nanotubes include gold, platinum, titanium, rhodium, iridium, indium, copper, iron, palladium, gallium, germanium, tin, lead, tungsten, niobium, molybdenum, silver, nickel, cobalt, lanthanide metals, and alloys thereof.

Examples of such polymeric materials that can be used to coat the carbon nanotubes include multi-component polymers (advantageously where the multi-component polymer has at least two different glass transition or melting temperatures), nylon, polyurethane, acrylics, methacrylics, polycarbonates, epoxies, silicone rubbers, natural rubbers, synthetic rubbers, vulcanized rubbers, polystyrene, polyethylene terephthalate, polybutylene terephthalate, Nomex (polyisophthaloyl isophthalamide), Kevlar (poly terephthaloyl diamine), PEEK (polyetheretherketone), Mylar (polyethylene terephthalate), vinylon (vinylon fluoroelastomers), polytetrafluoroethylene, halogenated polymers such as polyvinyl chloride (PVC), polyester (polyethylene terephthalate), polypropylene, and polychloroprene.

When treating carbon nanotubes and/or fusing carbon nanotube nanostructured materials with radiation, at least one particle selected from the group consisting of photons, electrons, nuclei, and ion particles impacts the carbon nanotubes in an amount sufficient to break at least one carbon-carbon bond and/or carbon-dopant bond, thereby activating the nanostructures or performing ion implantation.

Contaminants that may be removed from fluids include pathogens, microbial organisms, DNA, RNA, natural organic molecules, molds, fungi, natural and synthetic toxins (such as chemical and biological warfare agents), heavy metals (such as arsenic, lead, uranium, thallium, cadmium, chromium, selenium, copper and thorium), endotoxins, proteins, enzymes and micro-and nano-particle contaminants.

The present disclosure also relates to methods of purifying fluids, including liquids and gases, by removing at least one of these contaminants from the fluid. In the method, the contaminated fluid is contacted with a nanomaterial as described above, such as a nanostructured material comprising defective carbon nanotubes selected from the group consisting of impregnated, functionalized, doped, charged, coated and irradiated nanotubes and combinations thereof.

The activated nanostructures may be treated and/or activated with a component that alters the biological or chemical activity of the fluid to be scavenged according to the methods described herein.

Further, the method allows for separating contaminants at least partially from the treated fluid to form different fluid streams of contaminants and treated fluid.

In one embodiment, the fluid to be removed is a liquid, such as water, natural and/or synthetic petroleum and its by-products, biological fluids, food products, alcoholic beverages, and pharmaceuticals.

One of the major problems with petroleum products is the latent growth of bacteria in the petroleum during storage. This is a particular problem for aviation fuels. The presence of such bacteria can severely contaminate and ultimately destroy the fuel. Thus, one major area of concern in the field of liquid purification is the removal of bacteria from natural and/or synthetic petroleum products. Natural and/or synthetic petroleum oils and their by-products include aviation, automotive, marine and locomotive fuels, rocket fuels, industrial and mechanical oils and lubricating oils, and heating oils and combustible gases.

The biological fluid described herein is obtained from animals, humans, plants, or comprises growth medium fluids used in biotechnological or pharmaceutical product processing. In one embodiment, the biological fluid comprises blood, human milk, and components of both.

In another embodiment, the food product comprises animal by-products such as eggs and milk, fruit juices, natural syrups and natural and synthetic oils used in the cooking or food industry, including but not limited to olive oil, peanut oil, flower oil (sunflower, safflower), vegetable oils and the like.

In addition to food products, one embodiment of the present invention relates to the treatment of alcoholic beverages. Due to the nature of alcoholic beverages, fermentation thereof can lead to contaminants in the final product. For example, oxygen is an undesirable contaminant in wine making processes. Because oxygen in the bottle can damage the wine, sulfites are typically added to absorb or remove this excess oxygen. However, due to health considerations, sulfites should be avoided. One aspect of the invention includes the use of the above-described nanostructured materials to treat wine to remove unwanted contaminants, such as oxygen. The purification process described herein would be beneficial to the wine industry as the process would eliminate or substantially reduce the need for sulfite in wine.

Another aspect of the invention includes a method of cleaning air to remove the above-mentioned contaminants.

The present disclosure also relates to methods of purifying water by contacting contaminated water with the activated nanostructured materials described herein. Contaminants such as salts, bacteria and viruses have been shown to be removed from water to levels of at least 3 logs (99.9%), such as at least 4 logs (99.99%) and at least 5 logs (99.999%) and to levels that are currently detectable, i.e., to 7 logs (99.99999%).

The contaminants again comprise pathogens, microbial organisms, DNA, RNA, natural organic molecules, molds, fungi, natural and synthetic toxins, heavy metals (such as arsenic, lead, uranium, thallium, cadmium, chromium, selenium, copper and thorium), endotoxins, proteins, enzymes and micro-and nano-particle contaminants. Desalination of water (i.e., where the contaminants comprise salt) is also of concern.

Drawings

Fig. 1 is an optical image of sample 1: coli without carbon nanotube nanostructured material (no sonication; fixation after 48 hours).

Fig. 2 is an optical image of sample 2: coli without carbon nanotube nanostructured material (sonication; fixation after 48 hours).

Fig. 3 is an optical image of sample 3: coli with carbon nanotube nanostructured material (sonication; fixation within 3 hours).

Fig. 4 is an optical image of sample 4: coli with carbon nanotube nanostructured material (sonication; fixation after 48 hours).

Fig. 5 is an AFM image of sample 2: coli without carbon nanotube nanostructured material (sonication; not fixed).

Fig. 6 is an AFM image of sample # 3: coli with carbon nanotube nanostructured material (sonication; fixation within 3 hours).

Fig. 7 is an AFM image of sample # 3: the three-dimensional transformation of fig. 6.

Fig. 8 is an AFM image of sample # 3: coli with carbon nanotube nanostructured material (sonication; fixation within 3 hours).

Fig. 9 is an AFM image of sample # 3: the three-dimensional transformation of fig. 8.

Fig. 10 is an AFM image of sample # 4: coli with carbon nanotube nanostructured materials (sonication; not fixed).

Fig. 11 is an AFM image of sample # 4: the three-dimensional transformation of fig. 10.

Fig. 12 is a photograph showing vertical nanotubes at rest (left panel) and vibrating due to fluid flow (right panel).

Fig. 13 is a photomicrograph of the edges of the nanostructured material attached to a 20 micrometer metal mesh superstructure.

Figure 14 is a photomicrograph showing the nanotubes themselves wrapped around the support structure fibers in the pores of the support superstructure (cellulose acetate).

Fig. 15 is a photomicrograph of torn edges of carbon nanotube nanostructured material.

Fig. 16 is a photomicrograph of a fused monolayer of carbon nanotube nanostructured material stretched and fused onto a support wire covering a 25 x 25 micrometer opening.

Fig. 17 is a photograph of a self-woven carbon nanotube nanostructured material.

Fig. 18 is a photomicrograph of free-standing carbon nanotubes fused at intersections to form a nanostructured material.

Fig. 19 is a photomicrograph of a free-standing self-woven nanostructured material.

FIG. 20 is a simulation of fluid flow dynamics around carbon nanotubes in a nanostructured material.

Fig. 21 is an image showing the results of the bacteria removal test.

Detailed Description

Fluid disinfection

As described herein, fluid disinfection in conjunction with nanostructures such as carbon nanotubes, metal oxide nanowires, and metal nanowires is believed to be due, at least in part, to the formation of unique nano-range germicidal zones that use aggregative forces to kill microorganisms and other pathogens.

For example, it is believed that during fluid disinfection, microorganisms come into contact with the nanostructured materials described herein, resulting in a focused force being applied to the microorganisms, breaking open the cell membrane and causing internal cell damage, thereby destroying the microorganisms or destroying their regenerative capacity. In this way, microorganisms can be sterilized from the liquid. Common microorganisms are 1-5 microns long and at least 100 times larger than nanostructures such as carbon nanotubes. Known examples of such organisms include E.coli, Cryptosporidium, Giardia lamblia, Entamoeba histolytica and many others.

Due to the large size difference, forces on the nanometer scale can be applied that are concentrated many times (e.g., several orders of magnitude) over forces based on microscopy. In the same way that the concentrated light provides the laser with intensity, the concentrating power provides the intensity for the destruction of microorganisms on a nanometer scale. Mechanical and electrical forces that are otherwise too small to be effective or energy intensive can therefore be used to effectively and efficiently destroy microorganisms on the nanometer scale.

It is believed that the mechanism by which the microorganisms can be destroyed in such a nanotechnology may act independently or in synergy with another mechanism. Non-limiting examples of such mechanisms include:

mechanical disruption of cell walls by focused forces, much like needle disruption of balloons;

vibration waves causing internal cellular damage to DNA, RNA, proteins, organelles, etc.;

vibration waves causing damage to cell walls and transport channels;

van der Waals force;

an electromagnetic force;

damage to cell walls and DNA by hydrogen bond cleavage near the nanostructure; and

cavitation erosion of damaged cellular structures caused by shock waves in the liquid.

Since the osmotic pressure in a typical microbial cell is higher than that of the surrounding fluid (assuming non-physiological conditions), the cell contents flow from high to low pressure, so even minor damage to the cell wall can cause total rupture.

MS2, which is commonly used as a surrogate in evaluating the treatment capacity of membranes to treat drinking water, is a single-stranded RNA virus, 0.025 μm in diameter and has an icosahedral shape. It is similar in size and shape to other water-related viruses, such as poliovirus and hepatitis virus.

Liquid desalination

The liquid desalination method according to the present disclosure is also based on nanomaterials such as carbon nanotubes, metal oxide nanowires and metal nanowires. One mechanism that is believed to be possible for liquid desalination with nanomaterials is to create an ion separation gradient between two films of the nanomaterial. When one nanomaterial membrane is positively charged and the other membrane is negatively charged, the charge difference between the two plates creates an ion separation gradient such that cations migrate to one side of the region and anions migrate to the other. The extremely large surface area on the nanomaterial membrane serves to create very high capacitance, enabling very effective ion gradients.

The desalination unit may incorporate two or more parallel supported conductive nanomaterial membrane layers, the parallel layers being electrically isolated from each other. Such layered nanostructured materials may be assembled at the intersection of the Y-junction channels. Two or more layers may be charged in either a static mode or an active mode, where the charge on each plate is in turn positive to neutral to negative to neutral (a positive to a negative) to create a salt trap between them or to electrically create a moving capacitor in the structure, causing the salt to migrate in a direction different from the water flow. The strong brine will flow out of one leg of the Y junction and the fresh water from the other leg.

The geometry, capacitance and morphology of the device can be optimized for hydrodynamic flow using complex function analysis such as residual methods, fitness functions and optimization algorithms. The basic unit of the device will vary over a wide range of joint geometries, where most of the liquid will continue to flow along the primary channel, although a smaller amount of liquid is withdrawn through the outlet channel.

Many of these base units can be used in parallel and/or in series to reduce salt concentration and increase overall treated liquid. To further concentrate the salt-liquid overflow, it is contemplated to use a heat pump to cool the near supersaturated salt liquid and heat the incoming feed liquid. The system can be actively monitored to apply the appropriate concentration prior to cooling. Salt crystallization will occur when the solution is cooled, as saturated solutions will more quickly convert to a supersaturated state at low temperatures. In salt water, this will have the effect of accelerating the crystallisation of salt in the salt water.

The final product of the desalination process will be a near salt-free liquid, such as removing contaminants including, but not limited to, crystallized salt or concentrated brine mixtures to levels of at least log 4 (99.99%) and can reach levels of (including) log 7(99.99999), with intermediate levels being log 5 and log 6 purity. In one embodiment, cooling the brine collection tank will accelerate crystallization and allow any remaining liquid to enter the process again.

According to one aspect of the present disclosure, a surface susceptible to biological material and other impurities or contaminants may be coated with a layer of nanomaterial to prevent microbial growth. Non-limiting examples of such nanomaterials include functionalized nanotube nanostructured materials that are functionalized with elements or compounds having antimicrobial properties, such as silver or alumina.

The present invention further relates to methods of making the nanostructured materials described herein. The method comprises an organic solvent evaporation method, a metal oxide nanowire method, a geometric weaving method, a vacuum filtration method and a nanostructure polymerization method. Each of these methods can produce nanostructures with nanomaterials embedded therein or composed of nanomaterials. Each of these membranes can implement the fluid purification treatment techniques disclosed herein.

In one embodiment, membranes made according to the present disclosure have high permeability to allow high fluid flow rates. The permeability of the nanomaterial membrane is generally controlled by its thickness and fiber density. Thus, a low fiber density ultra-thin, ultra-strong nanomaterial film is more transparent to fluid flow than a thick nanomaterial film. Accordingly, one embodiment of the present invention is directed to a film of fused nanomaterial consisting essentially of high strength carbon nanotubes.

To enhance its structural support and bond with other entities, the entire nanomaterial membrane may be coated with a metal, plastic, or ceramic. The defects may be removed from the film of nanomaterial by chemical, electrical, thermal, or mechanical means to enhance its structural integrity.

The entire nanomaterial membrane can be stimulated with static or dynamic electromagnetic fields such that specific absorption or exclusion of certain molecules can be induced when fine tuned. High frequency electrical stimulation can produce an ultrasonic self-cleaning effect. By utilizing the strength, Young's modulus, conductivity, and piezoelectric effects of the nanotube nanostructured material, the nanostructured material as a whole can stimulate the material to vibrate and dislodge contaminants from the surface to reduce fouling.

The starting carbon nanotubes typically contain iron particles or other catalytic particles that remain after the nanotubes are produced. In certain embodiments, it is desirable to clean the carbon nanotubes with a strong oxidizing agent, such as an acid and/or peroxide, or a combination thereof, prior to formation of the nanostructured material. After washing with strong oxidants, the iron typically found in carbon nanotubes is oxidized to Fe + + and Fe + + +. In addition, acid cleaning is beneficial for removing amorphous carbon that interferes with nanotube surface chemistry.

It is believed that the inactivated or positively charged iron has an important effect on removing microorganisms known to have a net negative charge. According to this theory, the microorganisms are attracted to the functionalized positively charged nanotubes. The resulting electric field of the now charged carbon nanotubes, partially filled and doped with iron, will destroy biological pathogens. Any positively charged hydrogen ions left behind and trapped inside the nanotubes during the acid wash also contribute to the electric field.

It is believed that this acid cleaning procedure also contributes to the high hydrophilicity of these functionalized carbon nanotubes and the resulting carbon nanostructure material. The cleaned carbon nanotubes are typically fabricated into nanostructured materials using one of the following methods. It should be noted that any of the following methods, as well as the methods described in the examples, can be used to produce the nanostructured materials described herein, whether single layer or multilayer nanostructured materials.

Organic solvent evaporation method

In organic solvent evaporation methods, nanostructured materials, such as disinfecting films, can be made by bonding the nanomaterial with a binder. Examples of binders are chemical binders such as glue, metallic binders such as gold, and ceramic binders such as alumina. Examples of nanomaterials are carbon nanotubes, silicon and other metal nanowires, and metal oxide nanowires.

According to this method, the carbon nanotubes may be mixed with a solvent such as xylene. In one embodiment, this dispersion is then placed in an ultrasonic bath for 5-10 minutes to depolymerize the carbon nanotubes. The resulting dispersion is then poured onto fiber paper to evaporate the organic solvent, and optionally heated moderately. After evaporation, the carbon nanotubes were deposited on a fiber paper. In addition, other polymeric materials may be added to the organic solvent to enhance the mechanical stability of the resulting structure; the concentration of such binding material may be 0.001-10% by weight of the solvent used.

Metal oxide nanowire method

In another aspect of the disclosure, the disinfection film is made of metal oxide nanowires. In this type of method, the metal mesh is heated in an oxidizing environment to a temperature in the range of 230 ℃ - & 1000 ℃ to produce metal oxide nanowires on the metal wires of the metal mesh. The metal mesh may comprise a metal selected from copper, aluminum and silicon. The metal oxide nanowires can have a diameter in the range of 1-100 nanometers, such as 1-50 nanometers, including 10-30 nanometers. Advantageously, the metal mesh surface is abraded to provide a surface texture to accept and retain nanotube moiety deposition resulting in better substrate adhesion.

Films made according to this method can be used alone to disinfect liquids, treated to strengthen their overall structure or coated with carbon nanotubes or other nanostructures to promote their activity. In the process of coating the carbon nano tube, the well dispersed single-wall or multi-wall carbon nano tube solution passes through the metal net, and the carbon nano tube is adhered on the surface of the metal oxide. This resulting web may or may not be heat treated, mechanically treated (e.g., with hydraulic pressure), chemically treated, or rapidly laser heated to enhance structural integrity. It may or may not be coated with metal, ceramic, plastic or polymer to enhance its structural integrity. The resulting web can also be treated with this nanotube solution several times until the appropriate design criteria are met. The support of the carbon nanotubes and/or such membranes can be altered to functionalize the materials so that they can chemically react with biomolecules to destroy, alter, remove, or separate them.

In this method, a metal mesh, such as a copper mesh, may be placed in a chemical vapor deposition chamber in an oxidizing environment. The reaction zone is heated to a temperature in the range of 230 ℃. to result in the production of metal oxide nanowires, while the chamber is under atmospheric air for a period in the range of 30 minutes to 2 hours. In certain embodiments, a dispersion of carbon nanotubes in a liquid may then be passed through the formed structure. After this treatment, the entire structure can be thermally annealed at 1000 ℃ under vacuum to strengthen the entire structure. Optionally, the carbon nanotubes can be treated in a solution of nitric acid and sulfuric acid to produce carboxyl functional groups on the carbon nanotubes.

Deposition method

In this method, the sterilization film may be made by vacuum depositing the carbon nanotube dispersion such that the carbon nanotube layer remains on the at least one substrate. Sonication can be used during deposition to aid in the dispersion and/or deagglomeration of the carbon nanotubes.

One contemplated process for the deposition method involves placing the carbon nanotubes in a suitable organic solvent or liquid and sonicating to disperse the carbon nanotubes during the deposition process. The solution may be placed in a vacuum filtration device equipped with sonication to further ensure carbon nanotube depolymerization. The nanomaterial in solution can be deposited on a substrate having a porosity small enough to capture carbon nanotubes but less than that of the contaminated substrateThe microorganisms removed by the dye fluid are large. The resulting NanoMesh can be removed by maintaining flatness using a supporting metal mesh during removal^TM. The porous matrix for capturing carbon nanotubes may also be removed by dissolving it in an acid or base, or oxidized to leave a free-standing carbon nanotube film.

According to an aspect of the present disclosure, the vacuum filtration method may be modified by aligning the nanostructures using an electromagnetic field during deposition. As in the previous method, the nanostructures are placed in a suitable solvent (organic solvent or liquid), sonicated to disperse the nanostructures in the solvent, and then placed in a vacuum filtration device equipped with an ultrasonic probe to prevent agglomeration of the nanostructures during deposition. Unlike the previous methods, when the mixture is vacuum deposited onto a porous substrate (e.g., with pore sizes up to centimeter dimensions), an electromagnetic field is applied during its deposition to align the nanostructures. This electromagnetic field can also be arbitrarily modulated in three-dimensional space and result in woven or partially woven-partially non-woven structures. The resulting membrane is then removed with the aid of a supporting metal mesh and the entire membrane is immersed in acid to remove the starting substrate as a sacrificial support.

The vacuum filtration process can be modified to allow for the creation of multilayer nanostructures. A suspension of nanostructures may be formed on a substrate in an organic solvent. For example, the solvent is removed under very low vacuum pressure, leaving a thin layer of nanotubes on a wire mesh, such as a 20 micron wire mesh. This layer may then be hardened and dried. This process can be repeated multiple times to produce multiple layers of NanoMesh^TM。

Air sedimentation manufacturing method

In this method, the nanostructures may be uniformly dispersed in a gas or liquid solution. For example, in a closed chamber, some of the nanostructures are released to act as fan blades to agitate the gas to cause the carbon nanotubes to disperse in the chamber. The gas may also be mechanically conditioned at a frequency sufficient to cause dispersion. When carbon nanotubes are added to the chamber, the nanotubes are charged by passing them through a large surface area electrode to a voltage sufficient to overcome van der waals attraction. This will prevent agglomeration. The nanotube-laden gas is now available for vapor deposition. By applying different voltages, the gas passes through the grounded mesh electrode. The nanotubes will adhere to this grounded screen electrode. The carbon nanotube structure material is at the most brittle stage at this time. The nanostructured material may now be exposed to ionizing radiation in order to fuse the structures together and/or coat the surface by Chemical Vapor Deposition (CVD), Plasma Enhanced Chemical Vapor Deposition (PECVD) or Physical Vapor Deposition (PVD) processing techniques or by chemical fusion techniques. The surface is then removed and subjected to a sputtering process sufficient to cover the nanostructures and join them together. The resulting film is then removed from the surface by reversing the surface charge to cause film peeling.

Nanostructure polymerization process

In the polymerization process, a film of a nanomaterial is produced by bonding a nanostructure to another nanostructure through polymer bonding.

One contemplated process for this method involves first sonicating some of the nanostructures (such as carbon nanotubes) in an acid solution. When carbon nanotubes are used, the acid will cut the nanotube length, exposing its ends and allowing carboxyl ions (COOH) to graft thereto. The resulting carboxyl-functionalized product is then treated with a concentrated acid to produce carboxyl groups (COOH) that are more reactive to crosslinking reactions such as condensation. This COOH functionalized nanostructure is then reacted at the carboxyl group to crosslink the two nanostructures together. The mixture is then allowed to react until all of the cross-linked network forms a film of fused nanomaterial.

Method for measuring bacteria in water

Samples prepared using the methods generally described above were tested multiple times using bacteria such as E.coli and MS-2 phage. MS-2 is a male-specific single-stranded RNA virus with a diameter of 0.025 μm and an icosahedral shape. It is similar in size and shape to other water-associated viruses (such as poliovirus and hepatitis virus) and it is a non-human pathogen.

The protocol for the tested removal of E.coli and MS-2 phages as well as bacteria from water in the following examples is in line with and generally follows the following literature: (i) standard Operating Procedure for MS-2Bacteriophage amplification/energy Margolin, Aaron, 2001University of New Hampshire, Durham, NH and (ii) Standard Methods for the evolution of Water and Water, 20 th edition, Standard Methods, 1998.APHA, AWWA, WEF, Washington, D.C. These criteria generally include the following procedures:

1) the nanostructured material is placed in a test chamber designed to contain the nanostructured material to be excited. The tank is clamped to prevent leakage of the challenge solution.

2) The sterile drain was connected to a sterile Erilenmeyer flask using a rubber stopper.

3) The inflow opening is opened and the excitation material is introduced through the opening.

4) After introduction of the stimulating material, the inflow was closed and a thick liquid stream was pumped through a discharge hose connected to the test chamber by a commercially available pump.

5) Suction was continued until all the challenge material had entered the sterile Erilenmeyer flask, at which time the pump was turned off.

6) In a 15ml conical centrifuge tube, 0.1ml of challenge material was placed in 9.9ml of water or phosphate buffered saline solution (commercially available).

7) 15ml conical centrifuge tubes were placed in a commercial vortex mixer and mixed for about 15 seconds.

8) Approximately 0.1ml of the mixture was removed from the centrifuge tube, added to a second centrifuge tube containing 9.9ml of water or phosphate buffered saline solution (commercially available), and the vortex mixing described above was repeated.

9) 0.1ml of the mixture was removed from the centrifuge tube and placed on a Tryptic Soy Agar (TSA) plate (Remel, Cat. 01917), where the mixture could be spread on the agar surface with a sterile gummer. Surface-dried for 15 seconds, and then placed in a commercial incubator at 36 ℃ for 18-24 hours.

10) After incubation, the plates were removed from the incubator and placed on a backlight plate counter. Those plates that appeared to have 25-300 cfu/plate (1: 10,000 dilution) per plate were counted. The control group and test plate were counted in the same manner.

11) The number of viruses or bacteria counted and the dilution factor at which they were counted were recorded and the average of the number of plates multiplied by their corresponding dilution factor and divided by the amount of diluent used per plate. From this, the amount of virus or bacteria in the starting sample was calculated as shown below.

The procedure used in the tests with MS-2 is described in more detail below.

First by reacting MgCl₂(or CaCl)₂) Addition to the required amount of DI water to prepare 1% MgCl₂(or CaCl)₂) And (3) solution. A typical example is 1.0g MgCl₂99ml DI water. This solution was autoclaved and cooled.

A phosphate buffered saline solution formulation (1 x PBS) was then prepared by adding the phosphate buffered saline powder concentrate to the required amount of DI water. A typical example is 4.98g PBS/500ml DI water. This solution was also autoclaved and cooled.

The streptomycin/ampicillin antibiotic solution formulation (Strep/Amp) was then made by adding streptomycin sulfate to the required amount of DI water. A typical example is 0.15g Strep/100ml DI water. Ampicillin sodium salt was then added to the solution. A typical example is 0.15g Amp/100ml DI water. This solution was filtered into a sterile container through a 0.22 μm syringe filter.

The E.coli stock culture preparation was made by first making the desired volume of pancreatin soybean broth. The previously prepared streptomycin/ampicillin antibiotic solution was mixed with T-soy in a ratio of 1: 100 (1.0ml Strep/Amp/100ml T-soy).

Then 1% MgCl was added in a ratio of 1: 200₂Solution (0.5ml MgCl)₂100ml of T-soy), and then E.coli (10ml of E.coli/100 ml of T-soy) in a ratio of 1: 10. The E.coli strain used herein was the HS (pF amp) R strain (E.coli with strep/amp resistance plasmid inserted). Commercially available (American Type Culture Collection (ATCC)) E.coli strain C3000 can also be used.

The T-soy broth/E.coli culture was then placed in a 37 ℃ shaking water bath (or rotary shaker in a 37 ℃ incubator) and shaken vigorously for 2.5-3.0 hours (or the time for the E.coli to reach the mid-logarithmic growth phase in its growth cycle). This shaking step provides oxygen to the entire culture so that it is not anaerobic and growth is inhibited. The culture was then removed from the incubator and stored at 10 ℃.

The propagation of the MS2 phage was carried out as follows: first, a liquid culture of MS2 (about 1X 10)¹⁰-1×10¹¹MS2/500ml T-soy broth) was added to the T-soy broth, followed by incubation at 37 ℃ for 12-18 hours. The MS2 strain used was a commercially available specimen (ATCC (American Type CultureCollection), Cat. No. 15597-B1).

The culture was transferred to a centrifuge tube of appropriate size and centrifuged under the following conditions: centrifuge for 10 minutes at 10,000rmp, 4 ℃. After centrifugation, the supernatant was decanted, taking care not to disturb the particles. The MS2 stock solution is generally stored at 10 ℃.

MS2 counting is generally performed in the following manner. The 1 × coating was prepared by mixing and boiling the following in 1000ml of DI water.

a.15 g T-soy broth

b.7.5 g of bacterial agar powder

c.5 g Yeast extract

d.2.5 g NaCl

e.0.075 g CaCl₂

4 to 5ml of the coating was then dispensed into test tubes and autoclaved at 121 ℃ for 15 minutes, after which the test tubes were removed from the autoclave and placed in a 57 ℃ water bath for immediate use or stored at room temperature for future use. If left to store, the coating will harden and require re-autoclaving. The coating can only be re-autoclaved several times until the color becomes very dark, almost black.

One skilled in the art knows how to serially dilute the sample ten times in PBS to achieve the desired dilution point. Shortly after removing the aforementioned test tube containing the coating from the water bath, approximately 0.1ml of the desired sample diluent and 0.2ml of the aforementioned E.coli host may be fed into the coating. About 30. mu.L of streptomycin/ampicillin antibiotic solution may be added based on the mixed culture samples. It is important to note that the injection of 0.1ml of diluted sample represents a tenfold additional dilution. Thus, when 0.1ml of 10^-1When the dilution was placed in the coating, the resulting dilution on the T-soy plate was 10^-2. To coat 10 with^-1Dilute, 0.1ml of the starting undiluted sample was injected into the coating. To apply the 10 ° dilution, 1.0ml of the starting undiluted sample was injected into the coating using the same volume of E.coli host (0.2 ml).

The diluted sample and MS2 were mixed throughout the coating without vibration. The coating and its contents were added to a T-soy plate, which was rotated in a circular motion so that the coating was evenly distributed on the agar surface. After a few minutes, the coating becomes hard, at which time it is incubated at 37 ℃ for 12-18 hours.

When the culture is complete, the MS2 phage region will appear as a circular clean region in the e.

Negative and positive control groups are typically used in this analysis. The negative control group included adding only E.coli to the coating (no sample) to determine if E.coli was properly grown and if there was any phage or bacterial contamination. Additional controls that can also be used to determine these factors can be performed by placing a smaller volume of E.coli host (without MS2 or a coating) on a T-soy plate and detecting the resulting colony morphology.

The positive control group included adding only E.coli to the coating (no sample) and then coating. Once the coating was evenly distributed on the panel surface, a small volume of the MS2 stock solution was placed on each spot across the surface of the coating. After incubation, the presence of the phagocytic region in these spots indicates that the MS2 phage can efficiently infect E.coli hosts.

PFU/ml (phagemid forming units/ml) was determined in the starting undiluted sample:

for example, if the dilution factor is 10^-835 phagocytic zones were observed on the plate of (a), the PFU in the starting sample was:

using the above method and as exemplified by the following samples, there is strong adhesion between the bacteria and the carbon nanotube nanostructured material. Under the action of ultrasonic wave, bacteria are adhered to the surface of the carbon nano tube nano structure material. It is believed that the same adhesion occurs when the E.coli suspension passes through the nanomesh of carbon nanotube nanostructured material.

Furthermore, it is believed that the integrity of the bacterial cells is destroyed upon interaction with the carbon nanotube nanostructured material. For example, bacterial testing using the nanostructured materials described herein indicates a failure mechanism in which the shell/cell wall is completely destroyed. Such disruption apparently occurs because a breach in cell wall integrity caused by a difference in osmotic pressure between the interior of an intact cell and the exterior of the cell can lead to catastrophic failure of the cell wall. Thus, when the integrity of the cell wall/shell is compromised, those osmotic pressure differences will cause the bacteria to disintegrate.

For example, example 3 shows that the presence of bacteria-free DNA and proteins found in the filtrate evidences the destruction of E.coli. As seen in example 3, the damaged cells were dispelled with a stream of water. Thus, the carbon nanotube nanostructured materials of the present invention not only can completely destroy bacteria, but also are non-contaminating due to the establishment of bioburden, which will provide longer lifetimes than currently used materials.

The following non-limiting examples will further illustrate the invention and are not intended to be a complete exemplification of the invention.

Example 1: fabrication of activated defective nanostructured materials

The activated nanostructured material is made from commercially available purified carbon nanotubes. These nanotubes were placed in 50ml conical centrifuge tubes to which a volume of 45ml of concentrated nitric acid was added. The centrifuge tube was shaken vigorously for 2-3 minutes to mix the acid with the nanotubes and then centrifuged at 2,500rpm for 5 minutes to pellet the nanotubes.

The yellow supernatant was decanted and washed repeatedly with nitric acid. The carbon nanotubes were then washed 2-3 times with water to reduce the acid concentration to a level where the acid does not react with the isopropanol used in the following step.

100mg of carbon nanotubes rinsed with nitric acid/water was then added to 400ml of commercially pure isopropanol and sonicated in a Branson 900B sonicator at 80% power until the carbon nanotubes were well dispersed (approximately 10 minutes). The mixture was further diluted by adding 2 liters of isopropanol so that the total volume of the resulting mixture was 2.4 liters. This diluted mixture was sonicated for an additional 10 minutes.

800mg of commercially available 200nm diameter silica nanofibers were then homogenized in 500ml of commercially pure isopropanol at full power for 10 minutes in a commercially available blender. Additional 1 liter of commercially pure isopropanol was then added to dilute the homogenized mixture.

The previously prepared mixture of carbon nanotubes and silica nanofibers was mixed and then sufficient (Q.S.) isopropanol was added to give 4 liters. The 4 liters solution was then sonicated with a "Branson 900B sonicator" at 80% power for 15 minutes, causing the carbon nanotube nanomaterial to disperse uniformly.

The entire 4 liters of solution was then deposited onto a 16 square foot area of a commercial 5 micron polypropylene nonwoven fusion fabric. Approximately half of the solution was passed through the polypropylene fabric at 1/2 inches Hg vacuum pressure. The remaining 2 liters of solution was then passed through the fabric at a pressure of 5 inches Hg until the remaining solution passed through the polypropylene fabric and the carbon nanotube silica suspension was deposited on the fabric.

The resulting nanostructured material (referred to as NanoMesh)^TM) Removed from the fabric and allowed to air dry at room temperature for 2 hours to form activated carbon nanotube nanomaterial structures.

Example 2: purification test of nanostructured materials using E.coli

This example describes the purification test of water contaminated with E.coli stock culture purchased from the American Type Culture Collection (ATCC).

By using a starter solution (4X 10 per ml) of a first rehydrated E.coli stock culture ATCC #25922⁷±2×10⁷Colony forming units (cfu/ml)) excited the carbon nanotube nanostructured material produced according to example 1 for bacterial analysis. One circulation of the reconstituted stock was removed using a sterile biological circulatory system (commercially available), smeared in strips on commercially available blood agar plates and incubated at 36 ℃ for 12-18 hours. The culture was then removed from the incubator and checked for purity.

One cycle of the cultured culture was removed using a sterile biological circulation system (commercially available) and placed in 10ml sterile commercially available tryptic soy broth (Remel, cat. No. 07228). Coli was then grown overnight in the resulting trypticase-soy broth to form a 1X 10⁹Stock culture of cfu/ml. 1ml of stock culture was added to 100ml of water for challenge testing. The resulting excited water was then passed through the carbon nanotube nanostructured material fabricated according to example 1.

The tests were carried out according to the "Standard Methods for the administration of Water and Water" cited above. The results of testing following the above protocol demonstrate that greater than 6 logs (> 99.99995%) to greater than 7 logs (> 99.999995%) of E.coli can be consistently removed when the excited material is passed through the carbon nanotube nanostructured material fabricated according to example 1.

The test results confirmed the removal rate, which exceeded EPA drinking water standards for removing bacteria from water. EPA standards specify that 6 logs (> 99.99995%) of e.coli are removed to achieve potable water. Improved purification with higher log removal of E.coli has been achieved in the test by exciting carbon nanotube nanostructured materials with higher concentrations of E.coli challenge material made as described above. The test using higher concentrations demonstrated greater than 7log removal. Independent testing of carbon nanotube nanostructured materials made according to example 1 using the test procedure described in this example confirmed that such materials completely blocked e.

Example 3: chemical analysis of sterile post-challenge filtrate

This example describes the chemical analysis of the filtrate from the e.coli challenge test performed as described in example 2 on carbon nanotube nanostructured material made according to example 1. This example provides proof of purification via disruption of e.coli that passed through the carbon nanotube nanostructured material of the invention. The presence of DNA and protein in the challenge filtrate confirmed the evidence of purification by destruction of contaminants (e.coli).

Excitation tests were carried out according to example 2, with the exception that the composition of the excitation material was 1X 10⁸cfu/ml E.coli. All 100ml (all 1 × 10) were put under vacuum pressure of 1/2 inches Hg¹⁰cfu) passing this excitation solution through a carbon nanotubeA nanotube nanostructured material. Control filtrate was obtained by passing the E.coli challenge filtrate through a commercially available 0.45 micron millipore filter. The resulting control and challenge filtrates were then analyzed by a commercially available spectrometer to determine the presence of protein and DNA. The challenge filtrate was not concentrated. However, analysis of the filtrate using a commercially available spectrometer showed 40. mu.g/ml DNA and 0.5mg/ml protein. Protein and DNA concentrations at these levels in the unconcentrated challenge filtrate were 6-fold higher than the control test material. These concentrations confirm that the carbon nanotube nanostructured material destroys e.

Example 4: purification test for water contaminated with MS-2 phage virus

This example describes the purification tests performed on water contaminated with MS-2 phage virus using the Procedure described above and the Procedure described in "Standard Operating Procedure for MS-2Bacteriophage amplification/Enumeration, Margolin, Aaron, 2001, An EPAReference protocol". MS-2 phage viruses are commonly used to evaluate the treatment capacity of membranes designed for treating drinking water (NSF 1998). The pressure challenge for this example was performed using the protocol described above with 100ml challenge solution. The MS-2 excited material was prepared according to the procedure outlined above.

In this test, eighty (80) films of carbon nanotube nanostructured material made according to example 1 were excited. The challenge material used was water contaminated with MS-2 phage virus to a concentration of 4X 106. + -. 2X 106 pfu/ml.

Of the 80 units tested, 50 units achieved MS-2 removal of 5log (99.999%) or greater than 5log (> 99.9995%). The remaining 30 units showed MS-2 removal of 4 logs (99.99%) or greater than 4 logs (> 99.995%). Although the EPA standards recommend 4 logs of MS-2 phage removal to obtain drinking water, it is believed that better sensitivity (higher log removal) can be achieved with higher log of MS-2 challenge. Improved purification with higher log removal of MS-2 phage has been achieved in the test by exciting the carbon nanotube nanostructured material made according to example 1 with higher concentrations of MS-2 phage challenge material made as described above. Independent testing of the carbon nanotube nanostructured material fabricated according to example 1 confirmed that this material completely blocked the MS-2 bacteriophage.

Example 5: purification test of arsenic (As) -contaminated Water

This example describes the purification test of arsenic contaminated water. In this test, a stock solution containing 150 parts per billion arsenic in 100ml of water was passed through a carbon nanotube nanostructured material made according to example 1. A sample of the treated water was analyzed according to EPA method # SM 183113B. The excitation filtrate analysis demonstrated that the arsenic level was reduced by 86% ± 5% after passing the excited treated water through the carbon nanotube nanostructured material of the present invention once.

Example 6: removal of pollutants from aircraft fuel

A sample of contaminated jet fuel (JP8) was obtained from a 33,000 gallon oil storage tank at the american Air Force Research facility located at the Wright Patterson Air Force base. After collection, the samples were cultured on trypticase-soy agar and found to contain three bacteria: two species of bacilli and one species of coccobacillus. The samples were separated in two 2 liter containers each. Both containers provide two distinct layers, jet fuel on the top and water on the bottom. Vessel a contains a heavily contaminated growth layer at the interface between the water and the fuel. Container B showed only mild contamination. Challenge test bacteria were obtained from the interface of fuel and water in vessel B.

After homogenizing the fuel/water/bacteria for 1 minute under vigorous vibration excitation test, 200ml of the fuel/water/bacteria excitation mixture was passed once through the carbon nanotube nanostructured material made according to example 1 using 3 inches Hg vacuum pressure.

The fuel/water/bacteria challenge filtrate sample was allowed to separate into its fuel-water components and four test samples were obtained from each component. Each test sample was spread on agar. The samples were then incubated at 37 ℃ to analyze bacterial growth and at room temperature to analyze mold growth. No bacterial or fungal culture growth was observed on the challenge filtrate test plates after 24 and 48 hours of sample incubation. The control samples provided vigorous colonies for bacterial and mold growth after 24 and 48 hours of incubation. The results demonstrate that the carbon nanotube nanostructured material made according to example 1 completely blocked bacteria in the fuel because the bacteria and mold removed from the fuel with the test protocol were beyond the measurement limits.

Example 7: research on interaction of escherichia coli and carbon nanotube nano-structure material

The carbon nanotube nanostructured material made according to example 1 was rinsed 6 times with DI water. The rinsed carbon nanotube nanostructured material was diluted in DI water to a concentration of 10,000 ppm.

Preparation of E.coli suspension:

the above E.coli culture was prepared to 5X 10 in pure water⁹CFU/ml concentration.

Preparation of control slide sample # 1:

a drop of the prepared E.coli suspension was placed on a commercially available glass microscope slide (American Scientific Products, microscope slide, flat slide, Cat. No. M6145, size 75X 25mm) which was washed with sulfuric acid and rinsed with DI water. The drop of E.coli suspension was applied and allowed to air dry and frozen at 4 deg.C for 48 hours. The prepared slides were passed through a flame for heat fixing in a manner known in the art.

Preparation of the test suspension:

the remaining E.coli suspension prepared as described above was separated in two Erlenmeyer flasks to be divided into two equal parts (suspensions #1 and # 2).

Preparation of suspension # 1:

suspension #1 was diluted with DI water to an E.coli concentration of 2X 10⁹CFU/ml。

Preparation of suspension # 2:

the carbon nanotube nanostructured material produced according to example 1 was added to suspension # 2. Suspension #2 was diluted with DI water to the same E.coli concentration as suspension # 1. The concentration of carbon nanotube nanostructured material produced according to example 1 was 625 ppm.

Ultrasonic treatment and centrifugation:

suspensions #1 and #2 were sonicated simultaneously for 3 minutes using a Branson-2510 sonicator. These suspensions were centrifuged in a commercial centrifuge at 2500rpm for 2 minutes to pellet them, which were then decanted to leave 1ml of supernatant (and the particles suspended in suspensions #1 and # 2). The particles of suspensions #1 and #2 were then used in the samples described below.

Sample # 2:

a drop of suspension #1 was placed on the above glass slide to prepare sample 2, and frozen for 19 hours. After freezing for 19 hours, the unfixed sample was studied using an Atomic Force Microscope (AFM). Sample #2 was then placed in a refrigerator at the same temperature mentioned above for 24 hours. After 24 hours of freezing, sample #2 was heat fixed using methods known in the art. Sample #2 was stained with gram crystal violet dye using methods known in the art. Optical microscopy analysis was then studied.

Sample # 3:

a drop of suspension #2 was placed (and smeared) onto a glass slide to prepare sample 3. Heat fixation was performed for 3 hours after the ultrasonic treatment. Sample #3 was stained with gram crystal violet dye using methods known in the art. Sample #3 was placed in a refrigerator at the same temperature as mentioned above. After 19 hours, sample #3 was removed from the refrigerator and analyzed with AFM without fixation. Sample #3 was returned to the refrigerator for 24 hours, after which optical microscopy was performed.

Sample # 4:

sample #4 was prepared in the manner described for the preparation of sample #2, except that suspension #2 (instead of suspension #1) was used.

Optical microscopic analysis:

samples were studied in immersion oil under an Olympus light microscope at 1000 x magnification. Digital images were obtained with an Olympus DP10 CCD.

Samples #1 and #2 (bacterial suspension without carbon nanotube nanostructured material) both show images of E.coli cells uniformly dispersed over the entire surface of the slide (see FIGS. 1 and 2). The figure illustrates bacteria with clear edges indicating that the bacterial cells are intact. No change in shape was found after storage in a refrigerator in a dry state for 2 days. No change in bacterial cell morphology was detected between the heat-fixed and stained samples after 3 hours of sample preparation or after 2 days of storage in a refrigerator in the dry state.

Sample #3 shows complete absence of bacteria on the area of the slide where no nanotubes were observed. Only a small amount of carbon nanotube nanostructured material was observed at the periphery of the painted area. Most of the carbon nanotube nanostructured material had been washed off the glass slide when excess violet dye was washed off the glass slide. Bacterial enrichment was observed at the edges of the carbon nanotube nanostructured material (fig. 3). The bacterial region separates the particles as indicated by the purple color.

Sample #4 also shows the presence of e.coli at the edges of the carbon nanotube nanostructured material, but appears as a faint spot in the figure (fig. 4).

Atomic force microscopy analysis

Atomic Force Microscopy (AFM) was performed in tapping mode in a Veeco Dimension 3100 scanning probe system.

Sample #2 shows E.coli tightly packed together (FIG. 5). All cells had sharp edges. It is noted that when comparing the AFM image of sample #2 before heat treatment (fig. 5) with the optical image of this sample after heat treatment (fig. 2), a reduction in the size and packing density of the bacteria can be found.

Sample #3 shows some cells inside the carbon nanotube nanostructured material (fig. 6). At least one single cell is evident in the upper middle of the image. Coli cell wall edges are frayed.

The disaggregated structure of the E.coli cells was also recognizable in the 3D image (FIG. 7). Some diffusion material in the carbon nanotube nanostructured material can also be seen.

Larger surface areas of sample #4 than shown in fig. 10 were studied and all e.coli cells were lysed outside the identified spots. However, it can be seen that there are diffuse E.coli fragments inside the carbon nanotube nanostructured material.

After sonication of the E.coli and carbon nanotube nanostructured materials in DI water, the two components agglomerated due to electrostatic and van der Waals forces. At the limit of detection, all bacteria in the suspension were observed to contact and adhere to the carbon nanotube nanostructured material. There were no longer free E.coli cells in suspension # 2.

Coli cells begin to disintegrate immediately or shortly after the cells are in intimate contact with the nanotubes. The bacteria thus appear to spread out their sharp edges and the bacterial contents appear to spread out of the cell. This process started after 3 hours of development (fig. 6 and 8), and after 22 hours the spread left so that it was difficult to identify individual bacteria (fig. 10).

Unless otherwise indicated, it is to be understood that all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated otherwise, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention.

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims (38)

1. A material for removing or separating contaminants from a fluid, the material comprising

Carbon nanotubes, and

a porous matrix for the carbon nanotubes, the porous matrix being permeable to the flow of the fluid,

wherein the plurality of carbon nanotubes include:

a distortion of a crystal lattice is generated,

at least one functional group, and,

fused or bonded to the porous matrix, another carbon nanotube, or a combination thereof.

2. The material of claim 1, wherein the porous matrix comprises at least one component selected from the group consisting of fibers, matrices, and particles.

3. The material of claim 2, wherein the fibers, matrix, and particles are selected from ceramic materials and polymeric materials.

4. The material of claim 3, wherein the polymeric material comprises a single or multi-component polymer.

5. The material of claim 4, wherein the single or multi-component polymer comprises: nylon, acrylic resin, methacrylic resin, epoxy resin, silicone rubber, polystyrene, polyisophthaloyl metaphenylene diamine, polyparaphenylene terephthalamide, polyether ether ketone, viton fluoroelastomers, polytetrafluoroethylene, polyvinyl chloride, polyester, polypropylene, and polychloroprene.

6. The material of claim 5, wherein the polyester comprises: polyurethanes, polycarbonates, polyethylene terephthalates, and polybutylene terephthalates.

7. The material of claim 4, wherein the multicomponent polymer exhibits at least two different glass transition or melting temperatures.

8. The material of claim 3, wherein the ceramic material is at least one selected from the group consisting of: boron carbide, boron nitride, boron oxide, boron phosphate, spinel, garnet, lanthanum fluoride, calcium fluoride, silicon carbide, carbon and its allotropes, silica, glass, quartz, alumina, aluminum nitride, zirconia, zirconium carbide, zirconium boride, zirconium nitrite, hafnium boride, thorium oxide, yttrium oxide, magnesium oxide, phosphorus oxide, cordierite, mullite, silicon nitride, ferrite, sapphire, steatite, titanium carbide, titanium nitride, titanium boride, and combinations thereof.

9. The material of claim 2, wherein the particles have a diameter of up to 100 microns.

10. The material of claim 1, wherein the amount of carbon nanotubes present in the material is sufficient to remove or separate the contaminants in a fluid flowing into contact with the material.

11. The material of claim 1, wherein the carbon nanotubes comprise atoms other than carbon.

12. The material of claim 1, wherein the functional group comprises at least one of the following groups: an organic functional group, an inorganic functional group, and combinations thereof.

13. The material of claim 12, wherein the functional group is attached to the surface of the carbon nanotube.

14. The material of claim 13, wherein the functional group is located at a terminal end of the carbon nanotube and is polymerized.

15. The material of claim 12, wherein the at least one organofunctional group comprises a linear or branched, saturated or unsaturated group.

16. The material of claim 12, wherein the at least one organofunctional group comprises at least one chemical group selected from the group consisting of carboxyl, amine, polyamide, polyamphiphilic molecules, diazonium salts, pyrenyl, silane, and combinations thereof.

17. The material of claim 12, wherein the at least one inorganic functional group comprises at least one fluorine compound of boron, titanium, niobium, tungsten, and combinations thereof.

18. The material of claim 12, wherein the at least one organic and inorganic functional group comprises a halogen atom or a halogenated compound.

19. The material of claim 12, wherein the carbon nanotubes comprise functional groups that have a non-uniform composition and/or density across the surface of the carbon nanotubes and/or across at least one dimension of the material.

20. The material of claim 12, wherein the carbon nanotubes comprise a substantially uniform gradient of functional groups across the surface of the carbon nanotubes and/or across at least one dimension of the material.

21. The material of claim 1, wherein the carbon nanotubes have a convoluted tubular or non-tubular carbocyclic nanostructure.

22. The material of claim 21, wherein the carbon nanotubes having a coiled tubular or non-tubular carbocyclic nanostructure are single-walled, multi-walled, nanotropolized, or combinations thereof.

23. The material of claim 22, wherein the carbon nanotubes having a coiled tubular or non-tubular nanostructure have a morphology selected from the group consisting of nanohorns, cylinders, nanospirals, dendrimers, trees, star nanotube structures, nanotube Y-junctions, and bamboo-like morphologies.

24. The material of claim 1, wherein the fluid comprises at least one liquid or gas.

25. The material of claim 24, wherein the liquid comprises water.

26. The material of claim 24, wherein the liquid is selected from the group consisting of petroleum and its by-products, biological fluids, food products, alcoholic beverages, and pharmaceuticals.

27. The material of claim 26 wherein the petroleum and its by-products comprise aviation, automotive, marine and locomotive fuels, rocket fuels, industrial and mechanical oils and lubricating oils, and heating oils.

28. The material of claim 26 wherein the petroleum and its by-products comprise aviation fuel and the contaminants comprise bacteria.

29. The material of claim 26, wherein the biological fluid is obtained from animals, humans, plants, or comprises a growth broth used in biotechnology or pharmaceutical product processing.

30. The material of claim 26, wherein the biological fluid comprises blood, milk, and components of both.

31. The material of claim 26, wherein the food product is selected from animal by-products, fruit juices, natural syrups, and natural and synthetic oils used in the cooking or food industry.

32. The material of claim 31 wherein the animal by-product comprises milk and eggs.

33. The material of claim 31, wherein the natural and synthetic oils used in the cooking or food industry comprise vegetable oils.

34. The material of claim 33, wherein the vegetable oil comprises olive oil, peanut oil, and flower oil.

35. The material of claim 26, wherein the alcoholic beverage comprises beer, wine, or white spirit.

36. The material of claim 1, wherein the contaminant is at least one selected from the group consisting of: salts, metals, pathogens, microbial organisms, DNA, RNA, natural organic molecules, molds, fungi, natural and synthetic toxins, endotoxins, proteins and enzymes.

37. The material of claim 36, wherein the natural and synthetic toxins comprise chemical and biological warfare agents.

38. The material of claim 24, wherein the gas comprises air.