CONRAD, Phil (5524 Turkeyfoot Lane, Manhattan, KS, 66503, US)
SANFORD, Bill (2617 Bulrush Lane, Naples, FL, 34105, US)
WINECKI, Slawomir (3004 Geneva Drive, Manhattan, KS, 66502, US)
JONES, David (6241 Zeandale Road, Manhattan, KS, 66502, US)
KNAPPENBERGER, Kyle (1135 SW Western, Topeka, KS, 66604, US)
ANDERSON, Don (1310 Woodland Drive, Deerfield, IL, 60015, US)
KOPER, Olga (3004 Geneva Drive, Manhattan, KS, 66502, US)
CONRAD, Phil (5524 Turkeyfoot Lane, Manhattan, KS, 66503, US)
SANFORD, Bill (2617 Bulrush Lane, Naples, FL, 34105, US)
WINECKI, Slawomir (3004 Geneva Drive, Manhattan, KS, 66502, US)
JONES, David (6241 Zeandale Road, Manhattan, KS, 66502, US)
KNAPPENBERGER, Kyle (1135 SW Western, Topeka, KS, 66604, US)
ANDERSON, Don (1310 Woodland Drive, Deerfield, IL, 60015, US)
| We claim: 1. A method of decontaminating one or more surfaces that have been exposed to one or more undesirable substances comprising the step of applying to said one or more surfaces a quantity of nanocrystalline particles capable of sorbing and/or neutralizing said one or more undesirable substances, said nanocrystalline particles forming a coating on said one or more surfaces, said coating acting as a barrier to prevent release of said one or more undesirable substances into the environment surrounding said one or more surfaces. 2. The method according to claim I , said surfaces being interior surfaces of a building. 3, The method according to claim 2, said surfaces having been exposed to toxic or odorous materials emitted by defective drywali. 4, A method of decontaminating an area and monitoring the effectiveness of said decontamination process for a particular length of time comprising the steps of: applying within said area a first quantity of nanocrystalline particles capable of sorbing and/or neutralizing one or more undesirable substances, said first quantity of nanocrystalline particles sorbing at least a portion of said one or more undesirable substances; placing within or adjacent said area a second quantity of nanocrystalline particles such that said second quantity of nanocrystalline particles contact a fluid within said area; and after a period of time, removing at least a portion of said second quantity of nanocrystalline particles and reaction products resulting from the neutralization of said one or more undesirable substances from said area and analyzing said portion of said second quantity of nanocrystalline particles and/or said reaction products to determine the presence and quantity of said one or more undesirable substances in said fluid so as to evaluate the effectiveness of the application of said first quantity of nanocrystalline particles. 5. The method according to claim 4, said area being an area within a building that has been exposed to toxic or odorous materials emitted from defective drywall. 6. The method according to claim 5. said step of placing a second quantity of nan ocrystal line particles within or adjacent comprising placing a filter containing said second quantity of nanocrystalline particles in a position so as to come into contact with said fluid. 7. A method of monitoring an area for the presence of undesirable substances comprising: contacting a surface or a fluid within said area with a quantity of nanocrystalline particles capable of sorbing and/or neutralizing one or more undesirable substances for a predetermined period of time; after said predetermined period of time has lapsed, collecting and removing from said area a portion of said nanocrystalline particles and reaction products resulting from the neutralization of said one or more undesirable substances; and analyzing said portion of nanocrystalline particles and/or said reaction products removed from said area to determine whether said one or more undesirable substances are present within said area. 8. The method according to claim 7, wherein the identity of said one or more undesirable substances is unknown at the time said surface or fluid is contacted with said quantity of nanocrystalline particles. 9. A method of determining the useful life of a Filter comprising nanocrystalline materials useful to sorb and/or neutralize one or more undesirable substances, said filter being disposed within fluid handling apparatus in order to remove said one or more undesirable substances from a fluid, said method comprising periodic monitoring of the level of said one or more undesirable substances sorbed on and/or neutralized by said nanocrystalline materials. |
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention generally pertains to methods of removing contaminants and undesirable substances from enclosed spaces, such as buildings, vehicles, mines, process vessels, and other structures, and particularly from various materials within or materials which define the enclosed space. More particularly, methods according to the present invention comprise contacting a surface within the enclosed space containing at least one contaminant with a quantity of sorbent particles, especially nanocrystalline particles selected from the group consisting of metal oxides, metal hydroxides, and combinations thereof for sorbing the contaminant.
Description of the Prior Art
During the housing boom of the mid 2000's, it has been reported that more than 500 million pounds of possibly defective Chinese drywall was imported into the U.S. The U.S. generally has the capacity to produce most of its requirements for drywall to be used in homes and other buildings. However, the devastating 2006 hurricane season, and housing boom that was occurring at the same time, prompted many builders to buy drywall from China. The defective drywall emits toxic compounds, especially sulfur-containing compounds, that not only produce noxious odors, but also causes metals, such as air conditioning coils, plumbing, duct work, and electrical wiring, to corrode. The fumes have also been associated with respiratory and sinus problems in some persons residing within a home constructed with this drywall. In some of these homes, the owners or occupants have been forced to move or entirely gut and replace the drywall and all metal components within the home.
Following the initial complaints, it was discovered that samples of Chinese drywall contained higher levels of sulfur-containing compounds than samples of American-made drywall. For example, the Chinese samples contained traces of strontium sulfide while the American sample did not. Strontium sulfide is a gray powder that emits a hydrogen sulfide, or "rotten eggs," odor when exposed to moist air. The Chinese samples also contained higher levels of hydrogen sulfide, carbonyl sulfide, and carbon disulfide than the American drywall. All of these compounds are potentially toxic, and carbon disulfide in liquid form is extremely flammable.
The extent of this defective drywall problem is presently unknown. Thus far, the majority of complaints have been from the U.S. Southeast, and Florida in particular, due to the warm, humid climate which tends to enhance or accelerate release of the sulfur-containing compounds from the drywall. It is believed that the tainted drywall from China was manufactured with mined gypsum containing high levels of strontium, rather than synthetic gypsum made from coal ash.
International Patent Application Publication WO 2007/041553, incorporated by reference herein, also discloses exemplary background information. SUMMARY OF THE INVENTION
In one aspect, the present invention is directed toward a process or protocol for the decontamination of surfaces that have been exposed to undesirable substances. In another aspect, the present invention is directed toward monitoring of an area to determine whether undesirable substances are present, identification of the contaminants, and/or the level at which they are present. In still another aspect, the present invention is directed toward the management and removal, at the source, of gases that continue to be emitted from contaminated surfaces, particularly after the removal of the source of contamination via a "leave behind" residual coating. In still another aspect, the present invention is directed toward continual removal of potential, remaining, airborne contaminants via an air filtration cartridge placed in an air handling system or apparatus, for example, in the HVAC system of a building affected by the contamination. In yet another aspect, the present invention is directed toward continual monitoring of air quality by periodic or continuous laboratory analysis of the filtration cartridge for quantitative contaminant content and correlation of this data to trends of ongoing indoor air quality. The present invention may comprise any combination of the foregoing aspects to provide a comprehensive contamination mitigation system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention comprises a process for the decontamination and/or monitoring of contaminant residues in an area, particularly an enclosed area. The contaminant may be present on surfaces within the area, embedded within materials in or defining the area, or in the atmosphere or in liquids located within the area.
In one embodiment according to the present invention, there is provided a method of decontaminating one or more surfaces within an area. In this embodiment, the surfaces are contacted with a surface treatment comprising sorbent particles, particularly nanocrystalline particles. The nanocrystalline particles comprise metal oxides, metal hydroxides, or combinations thereof, suitable for adsorbing and/or neutralizing undesirable substances located on said surface, or within the material having an exposed surface. The surface treatment is described in further detail below.
In cases in which the contaminant is embedded within and emanating from a particular material within the enclosed area, the surfaces of that material may be treated with sorptive particles (particularly nanocrystalline particles) according to the present invention in order to provide a barrier against further emission of contaminants in the surrounding environment,
In certain embodiments, at least one surface is coated with the surface treatment so that as undesirable substances are emitted from the material they are sorbed and/or neutralized by the surface treatment. Thus, the release of the undesirable substances into the surrounding environment is prevented.
In certain embodiments according to the present invention, application of the nanocrystalline particles with the contaminant or contaminated surfaces may occur in several fashions. For example, the nanocrystalline particles are preferably included within a foam, suspension, spray, fog, aerosol, paste, sol, liquid carrier, paint, coating, or gel and then sprayed or painted onto the exposed surfaces. The nanocrystalline particles may also be applied to the surface in dry form without the aid of a liquid, foam, or gel carrier. Regardless of how the particles are applied, the nanocrystalline particles are deposited on the surface, and in certain embodiments become adhered to the surface, so as to sorb (i.e., either by adsorption, absorption, or both) and/or neutralize contaminants as they become liberated from the materia! underlying the surface, thus preventing the contaminants from becoming dispersed in the gaseous atmosphere adjacent the surface or in other fluids with which the surface may come into contact with, such as water.
The foam, suspension, sol, liquid carrier or gel can be applied using a pressurized fluid stream such as water, steam, a compressed gas, such as air, nitrogen, or other inert gas, or simply a pressurized stream of the material containing the nanocrystalline particles. The foam, suspension, sol, liquid carrier, paint, coating, or gel may include another material such as a surfactant to assist in suspending the nanocrystalline particles therein or to assist in creation of the foam or gel while applying the particles to the surface.
The nanocrystalline particles used in conjunction with the present invention are selected from the group consisting of metal oxides, metal hydroxides, and combinations thereof. As used herein, the terms "metal oxides" and "metal hydroxides" refer to compounds containing a single metal ion (mono-metal oxides and hydroxides), compounds containing more than one metal ion (e.g., mixed metal oxides of the formula (Μ 1 ) χ (Μ 2 ) Y Ο Z ), and intimate mixtures of metal oxides and hydroxides. More preferably, the nanocrystalline particles are selected from the group consisting of metal oxides and metal hydroxides of Mg, Sr, Ba, Ca, Ti, Co, Fe, V. Mn, Ni, Cu, Al, Si, Zn, Ag, Mo, Zr and mixtures thereof. However, it is within the scope of the invention to employ any nanocrystalline metal oxide or hydroxide material including those recited in U.S. Patent No. 6,860,924, incorporated by reference herein. The outer surface of the nanocrystalline particles may be modified, or coated, especially with a second oxide or hydroxide different from the core material, such as disclosed in U.S. Patent No. 5,914,436, incorporated by reference herein, may be used. Preferably, the nanocrystalline particles have average crystallite sizes of less than about 20 nm, and more preferably from about 4-10 nm. The nanocrystalline particles also exhibit average surface areas of at least about 20 m 2 /g. more preferably from about 80-500 m 2 /g, and most preferably from about 85-250 m 2 /g. The nanocrystalline particles may also be in the form of a powder or the particles can be agglomerated into aggregates having particle sizes of between about Ι μιη and I mm. The nanocrystalline particles or aggregates may also be aggregated into granules or pellets having sizes of up to 5 mm, or between about 1 mm and 5 mm.
The surface coating step may be followed up with monitoring the quantities of undesirable substances that may be emitted from the surfaces despite the presence of the coating. In one embodiment, this monitoring is effected by installing within air handling apparatus located proximate or adjacent the at least one surface a Filter cartridge comprising the sorbent particles, particularly the nanocrystalline particles. As air is passed through the air handling apparatus, it also passes through the filter cartridge wherein undesirable substances emitted from the treated surfaces can be sorbed and/or neutralized by the nanocrystalline particles. Exemplary filter cartridges are described in co-pending U.S. Patent Application No. 12/548,060, entitled METHODS AND APPARATUS FOR CONTROL AND ELIMINATION OF UNDESIRABLE SUBSTANCES, filed August 26, 2009, which is incorporated by reference herein in its entirety.
The filter cartridge is occasionally replaced. Used filters can be analyzed for the presence of undesirable substances, in certain embodiments, the filter does not need to be removed from the air handling apparatus in order for the analysis to occur, especially if the apparatus includes sensors or other analysis means for real time sampling and analysis of the filter. Should undesirable substances be found, the user will know that further surface treatments may be necessary, or to look for other possible sources of contamination. Should the filter media contain trace amounts or substantially no undesirable substances, the user will know that the decontamination has been successful.
In certain embodiments according to the present invention, the monitoring protocol may be employed independent from the surface treatment in order to monitor levels of contamination in an area, such as on surfaces, in the air, or in water, in this embodiment, the nanocrystalline particles are positioned so as to come into contact with a fluid, such as air or water, carrying the suspected contaminant. The nanocrystalline particles then contact, sorb, and/or neutralize undesirable materials present within the fluid. The nanocrystalline particles, including the reaction products, can be routinely recovered and analyzed so as to determine whether contaminants are present in the area being monitored, and/or the extent of then- presence.
This monitoring system may be employed in environments where a contaminant is suspected but unidentified. The monitoring aspect of the present invention permits these contaminants to be characterized by forensic analysis of the nanocrystalline particles. It is important to note that the chemical structure of the sorbed material may be altered upon sorption by the nanocrystalline particles. Therefore, the forensic aspect requires reconstruction of the chemical make up of the contaminant based upon the reaction products obtained from the nanocrystaihne particles.
The nanocrystaihne particles may be contacted with the fluid containing the contaminant in a variety of manners depending upon the particular fluid involved. In one embodiment, the nanocrystaihne particles may be contained within filtration media, such as described above. For gaseous fluids, such as air or feed streams to industrial processes, the gas may be passed through a handling system having a filter cartridge (including, for example, a packed bed-type filter) installed therein. As the gas passes through the filter cartridge, the contaminant contacts the nanocrystalline particles carried thereby and are sorbed and/or neutralized. For liquids, a similar filter mechanism may be employed and is placed within liquid handling apparatus whereby the liquid to be monitored is passed through the cartridge. Periodically, the cartridge, in either the gas or liquid handling apparatus, may be replaced and the cartridge, and particularly the nanocrystalline particles and reaction products carried thereby, analyzed for the presence of undesirable substances. Alternatively, the cartridge need not be removed from the gas or liquid handling apparatus if the cartridge is equipped with sensing equipment for providing real time data pertaining to the presence or absence of undesirable substances.
In another embodiment, the nanocrystalline particles may be directly applied to a given area and then, after a predetermined exposure time, a sampling of the nanocrystalline particles and reaction products may be recovered and analyzed for the presence of known or unknown contaminants using a variety of analytical techniques, including energy dispersive X-ray analysis (EDX). In certain embodiments, the nanocrystalline particles are applied as described above to any surface or may be dispersed or suspended within a particular fluid. After being permitted to contact the surface or fluid for a predetermined period of time, a sample of nanocrystalline particles and reaction products may be scraped off the surface and collected or a sample of the fluid in which the particles and reaction products are dispersed or suspended may be taken.
In yet another embodiment, the nanocrystalline particles may be applied to any kind of support material which is then disposed so as to come into contact with the suspected contaminants. Particularly, the nanocrystalline particles may be coated or otherwise adhered onto a woven or unwoven textile material. The textile material may then be used to wipe down a surface that is being monitored for the presence of one or more known or unknown contaminants. After sufficient contact between the textile material and surface, the textile material can be analyzed for the presence of undesirable materials sorbed and/or neutralized by the nanocrystalline particles.
Preferably, contaminants to be addressed by the present invention are selected from the group consisting of acids, alcohols, compounds having at least one atom of P, S, N, Se or Te, hydrocarbon compounds, heavy metals and heavy metal containing compounds (especially Hg, Se, Pb, Cd, As, and compounds thereof), toxic metal compounds, bacteria, fungi, spores, viruses, toxins, and mixtures thereof. More preferably, the contaminant is selected from the group consisting of H 2 S, H2SO4, HC1, HNO3, C 1 -C20 thiols (mercaptans), cyanides (e.g., HCN), C 1 -C20 sulfides, C 1 -C20 oxysulfides (e.g., COS), C 1 -C20 disulfides, C 1 -C20 thiophenes, strontium sulfide, iron sulfide, sulfuric acid, S0 2 , CS 2 , butane thiol, and methylpyridine.
The present invention is further described with respect to the various embodiments described below. It is noted that these embodiments are described by way of example and should not be taken as limiting the scope of the present invention. The present invention has particular utility in the treatment of contamination that is a result of the presence of the aforementioned defective drywall by effectively treating surfaces and monitoring the surrounding air to determine whether off-gassing of undesirable substances is taking place. In applications in which the toxic materials from the drywall have damaged portions of the structure or fixtures within the structure (such as plumbing, HVAC equipment, and electrical wiring), one of skill in the art would appreciate that the defective drywall will need to be removed so that this damage can be repaired. However, in applications where the internal damage has not reached a critical level, it may be possible to avoid complete removal of the drywall, and instead simply apply the nanocrystalline particles on top of the drywall thereby forming a barrier to sorb, neutralize, and/or prevent further emission of toxic materials.
As noted above, the nanocrystalline particle formulation can be applied by spraying or painting, such as with an airless sprayer, so as to achieve essentially full coverage over all affected surfaces. In certain embodiments, the nanocrystalline particle formulation dries to a white color thereby allowing for visible inspection of the treated surface to ensure that a proper barrier has been created.
Following completion of the remediation, an air filter cartridge (with an air flow counter), such as those described above, can be installed within, or attached to (as in, for example, a fan) an air handling system such as the building's HVAC system. Data to be reported from the air flow counter at each required cartridge exchange assist in the accurate and reliable analysis associated with the ongoing monitoring function within this protocol. The cartridge provides significant indoor air quality benefits and important quality control assurances. Cartridges are to be replaced periodically and spent cartridges analyzed for sulfur and/or other contaminant content. In one embodiment, new cartridges are installed every month for the first 3 months following treatment of the building surfaces to establish accurate ambient sulfur and/or other contaminant baseline data. Once the baseline levels have been recorded, the cartridge is to be replaced every three months for analysis and reporting. Note, the precise timing of filter replacement/exchange may vary depending upon a particular application.
The effectiveness of the remediation process can be monitored on an ongoing basis. In one embodiment, the monitoring protocol requires an inspection and validation of the remediation efforts before, during and after the process. This will certify the process was done correctly. Filter cartridges installed in the HVAC systems of remediated buildings are designed to sorb and/or neutralize sulfur gases and other undesirable/residual contaminants/substances present in the remediated building. These filter cartridges are removed at specified intervals and tested to monitor the level of contaminants and resultant air quality in remediated buildings and validate the successfulness of the remediation process. Reports can be generated regarding the remediation process and can be furnished to the building owner, occupants, regulators, and insurance company.
Another aspect of the present invention pertains to a method of determining the useful life of a filter comprising nanocrystaUine materials that are useful to sorb and/or neutralize one or more undesirable substances. In operation, the filter is disposed within fluid handling apparatus (such as within an HVAC unit or other fluid handling system) in order to remove one or more undesirable substances from a fluid. The method comprises the periodic monitoring of the level of the one or more undesirable substances sorbed on and/or neutralized by the nanocrystaUine materials. In one embodiment, sensing equipment located on or within the air handling apparatus can be employed to monitor the filter's remaining useful life, or sorptive capacity for the one or more undesirable substances, and then alert the user when the filter's useful life is near an end so that the user may replace/exchange the filter. Yet another aspect of the present invention pertains not only to the decontamination and/or monitoring of toxic compounds or chemicals, but also to the decontamination and neutralization of biological materials, such as bacteria, viruses, fungi, spores, and toxins. The methods employed are similar to those described above, and monitoring for the presence of these biological materials after the initial decontamination treatment can be carried out as well.
The above-described monitoring process can be employed in addition to or independent of a decontamination process. Further, a broad number of possible applications for this monitoring process are envisioned in addition to the above-described defective drywall remediation application, including, but not limited to, the monitoring of waste water streams for contaminants, monitoring trace concentrations of specific compounds in feed streams to chemical processes, and monitoring pollutants present in exhaust gas streams.
Next Patent: LANCING DEVICE WITH IMPROVED GUIDANCE ASSEMBLY