REMOVABLE SMART SEQUESTRATION COATINGS FOR HAZARDOUS METALS

Abstract

Materials are disclosed for the safe sequestration and removal of hazardous contaminants from a surface. The materials can be sprayed, rolled, painted, brushed or dip coated onto any surface and allowed to dry and/or cure at room temperature or drying/curing can be accelerated by the application of heat to form a coating that entraps the contaminant therein. The coating and the entrapped contaminant can then peeled from the surface and safely disposed of to minimize hazardous waste. The coating includes a colorimetric additive that is specific to the contaminant, the coating and the contaminant producing a visual indication of contamination.

Claims

1. A coating formulation including one or more colorimetric indicators for application to a surface, the one or more colorimetric indicators, after application to the surface, indicating the presence of metallic contaminant(s) on said surface by metal specific color changes.

2. The coating formulation of claim 1 configured for application to the surface by spraying, casting, hard or soft rolling, dipping, painting or brushing on to the surface to form a film thereon, said coating formulation applied in one or more coatings.

3. The coating formulation of claim 2, following application to said surface and drying and/or curing having sufficient strength such that the film formed retains its structure and integrity when peeled from the surface, said peeled film entrapping or sequestering the metallic contaminants to provide safe remediation and disposal.

4. The coating formulation of claim 2 wherein the colorimetric indicators in the formulation provide a colored film portion indicating the presence the metallic contaminant and of the concentration of the metallic contaminant based on the intensity of the color change.

5. The coating formulation of claim 2, wherein the dried and cured coating can be mechanically peeled from the surface without releasing the entrapped or sequestered contaminant.

6. The coating formulation of claim 2 configured for application to smooth, porous or rough surfaces.

7. The coating formulation of claim 2 configured for application to surfaces comprising drywall, glass, metal, plastic, cement, or concrete.

8. The coating formulation of claim 1 comprising 0.02-0.3 wt % of a silver dispersion, 83-90 weight % of Deconpeel™ 5001, 0.2-1 weight % of a surfactant and 10-17 weight % deionized (DI) water.

9. The coating formulation of claim 8 wherein the dried or cured film provides a darkening of the grayish silver dispersion color when exposed to metallic Hg in the coating.

10. The coating formulation of claim 8 wherein the film is cured for 24 to 48 hours.

11. The coating formulation of claim 8, said film peeled from the surface by mechanical means with moderate force.

12. The coating formulation of claim 1 comprising 0-4% by weight Booth Coat 5201, 5-15 weight % of 1,5-diphenylthiocarbazone (Dithizone) in reagent alcohol, 0-1.5% by weight of Clinoptilolite and 79-90% by weight of Deconpeel 5001.

13. The coating formulation of claim 12 wherein the film shows a color change from tan to localized regions of pink in the presence of elemental Hg or Hg(II) species sequestered in the coating, a color change from tan to localized regions of blue in the presence of Cu(II) species sequestered in the coating, and a color change from tan to localized regions of grey in the presence of Ni(II) species sequestered in the coating.

14. The coating formulation of claim 12 wherein the film is cured for 24 to 48 hours.

15. The coating formulation of claim 12, said film peeled from the surface by mechanical means with moderate force.

16. The coating formulation of claim 1 comprising 70-85 weight % PlasticMask 7550, 0-1.5 weight % Clinoptilolite, 15-20 weight % alpha terpineol, 0.032-0.128 weight % 1,5-diphenylthiocarbazone (Dithizone), 0.1-2 weight % of a surfactant and 3-6 weight % water.

17. The coating formulation of claim 16 wherein the film shows a color change from pale yellow to localized regions of pink in the presence of elemental and mercury(II) species sequestered in the coating and a color change from tan to localized regions of tan-pink in the presence of Cadmium(II) species sequestered in the coating.

18. The coating formulation of claim 16 wherein the film is cured for 24 to 48 hours.

19. The coating formulation of claim 16, said film peeled from the surface by mechanical means with moderate force.

20. The coating formulation of claim 16 where the dried peeled film has a thickness from 0.2-0.35 mm for al single layer and 0.5-0.75 mm for two layer spray applied coatings.

21. The coating formulation of claim 1 comprising 70-85 weight % PlasticMask 7550, 0-1.5 weight % Clinoptilolite, 15-20 weight % alpha terpineol, 0.032-0.128 weight % of 1,5-dephenylcarbazide, 0.1-2 weight % of a surfactant and 3-6 weight % water 17.

22. The coating formulation of claim 21 wherein the film shows a color change from. pale pink to localized regions of deep purple in the presence of Cr(VI) species sequestered in the coating.

23. The coating formulation of claim 21 wherein the film is cured for 24 to 48 hours.

24. The coating formulation of claim 21, said film peeled from the surface by mechanical means with moderate force.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0015] The present disclosure described herein will become apparent from the following detailed description considered in connection with the accompanying drawings, which disclose several embodiments incorporating features of the invention. It should be understood, however, that the drawings are designed for the purpose of illustration and not as limits of the invention.

[0016] FIG. 1 is a schematic representation of an embodiment of the coating operation. Specific binding events for contaminants (in this example, ionic and elemental metal) are shown through symbols and visible color changes in the coating. The ionic metal species referred to herein are absorbed into the coating, the coating is cured and the presence of the metal ion is shown by a color change representative of the metal ion and/or its concentration.

[0017] FIG. 2 depicts the use of the coating based on a test protocol. As indicated, the contaminant on a substrate is absorbed by the coating formed on the substrate surface. The coating is dried or cured and the presence of the contaminate is indicated. The coating can then be removed leaving the original substrate decontaminated and the removed coating can be analyzed.

[0018] FIG. 3 depicts coating and peeling of a preferred embodiment of the present invention from porous cement brick with resulting color changes where: [0019] (a) depicts the regions deposited with 0.05 mL each of aqueous salt solutions of 0.01 M and 0.05 M Hg.sup.2+, 0.01 M and 0.05 M Cu.sup.2+, 0.05 M Ni.sup.2+ and 0.01 M Pb.sup.2+, [0020] (b) depicts the surface after applying and drying of a coating formulated with 1,5-Diphenylthiocarbazone (Dithizone) indicator, the Hg ion showing as pink and the Cu ion showing as gray, [0021] (c) depicts the initial peel off of a surface, [0022] (d) shows the surface when the coating is peeled partially off, and [0023] (e) depicts the result, with the invention completely removed from porous cement brick.

[0024] FIG. 4 depicts coating and peeling from a polyvinyl chloride (PVC) pipe surface with a preferred embodiment of the present invention showing color changes where [0025] (a) depicts the regions deposited with 0.05 mL each of aqueous salt solutions of 0.01 M and 0.05 M Hg.sup.2+, 0.01 M and 0.05 M Cu.sup.2+, 0.05 M Ni.sup.2+ and 0.01 M Pb.sup.2+, [0026] (b) depicts the surface after applying and drying of a coating formulated with 1,5-Diphenylthiocarbazone(Dithizone) indicator, the Cu ion showing as blue or green depending on concentration, the Hg ion showing as pink and the Ni ion showing as a light blue. [0027] (c) depicts the initial peel off of a surface, [0028] (d) shows a surface when the coating is peeled partially from the surface, and [0029] (e) depicts the result, with the coating completely removed from a PVC substrate surface.

[0030] FIG. 5 depicts coating and peeling from stainless steel with a preferred embodiment of the present invention showing color changes where [0031] (a) depicts the regions deposited with 0.05 mL each of aqueous salt solutions of 0.05 mL each of 0.01 M and 0.05 M Hg.sup.2+, 0.01 M and 0.05 M Cu.sup.2+, 0.05 M Ni.sup.2+ and 0.01 M Pb.sup.2+, [0032] (b) depicts the surface after applying and drying a coating formulated with 1,5-Diphenylthiocarbazone (Dithizone) indicator, the Cu ion showing as blue or green/brown depending on concentration and the Hg ion showing as pink, [0033] (c) depicts the initial peel off of the surface, [0034] (d) shows the surface when the coating is peeled about half way, and [0035] (e) depicts the result, with the coating completely removed from the stainless steel surface.

[0036] FIG. 6 depicts coating and peeling from painted drywall with a preferred embodiment of the present invention showing color changes on a drywall surface where [0037] (a) depicts the surface following deposit of 0.05 mL serially diluted 0.01 M and 0.05 M Hg.sup.2+(top panel), 0.01 M and 0.05 M Cu.sup.2+(middle panel), 0.05 M Ni.sup.2+ and 0.01 M Pb.sup.2+(bottom panel) and the application and drying a coating with 1,5-Diphenylthiocarbazone (Dithizone) indicator, the Hg ion showing as pink or orange, the Cu ion showing as green to brown and the Pb ion showing as gray, (b) depicts the initial peel off of the surface, (c) shows the surface when the coating is peeled about half way, and (d) shows the surface with the coating completely removed from a painted drywall.

[0038] FIG. 7 depicts coating formulated with 1-(2-pyridylazo)-2-napthol as another preferred embodiment of the present invention applied to a drywall with surface. The color changes are for Hg (pink), Cu (blue to pink) and Ni (pink to orange) ions shown where the increasing numbers are representative of decreasing metal ion concentration in the spotted regions.

[0039] FIG. 8 depicts coating formulated with 5-(4-dimethylaminobenylidene) rhodanine in another preferred embodiment of the present invention applied to a drywall surface. The color changes for Hg (orange), Cu (green to orange) and Ni (gray) ions are shown with increasing numbers representative of decreasing metal ion concentrations in the spotted regions.

[0040] FIG. 9 depicts a coating formulated with 1,5-Diphenylthiocarbazone in another preferred embodiment of the present invention applied to a drywall surface. The color changes for Hg (pink to orange), Cu (brown/green to gray), Pb (not visible) and a mixture of Hg and Cu (green to gray with a pink ring) ions are shown with increasing numbers representative of decreasing metal ion concentrations in the spotted regions. Influence on specific color development from co-existing metal ions is shown for various ratios of Cu(II) and Hg(II) in the example. The Table included therein identifies the ion concentrations colorimetrically shown in the Figure.

[0041] FIG. 10 depicts the coating formulated with 1,5-diphenylthiocarbazone in another preferred embodiment of the present invention applied to a drywall surface contaminated with mercury (II) compounds, namely mercuric chloride, mercuric oxide and mercuric sulfate in decreasing concentrations from right to left (40 μg to 40 ng) al showing as pink.

[0042] FIG. 11 depicts the coating formulated with 1,5-diphenylthiocarbazone in another example of the present invention applied to a drywall surface contaminated with mercury (II) compounds, namely mercuric bromide, mercuric iodide and mercuric sulfide in decreasing concentrations from right to left (40 μg to 40 ng).

[0043] FIG. 12 depicts the coating formulated with 1,5-diphenylthiocarbazone in another example of the present invention applied to a drywall surface contaminated with mercury (II) chloride as a function of coating age from day 0 through day 32, showing as pink to orange depending on decreasing concentration.

[0044] FIG. 13 depicts the coating formulated with 1,5-diphenylthiocarbazone in another example of the present invention applied to elemental mercury contaminated soil from a site identified as the Y-12 site.

[0045] FIG. 14 depicts the coating formulated with 1,5-diphenylcarbazide in another preferred embodiment of the present invention applied to a drywall surface contaminated with an aqueous solution of Cr(VI) containing salt at two different concentrations showing as purple to pink.

[0046] FIG. 15 depicts the coating formulated with 1,5-diphenylthiocarbazone in another preferred embodiment of the present invention applied to a drywall surface contaminated with an aqueous solution of cadmium (II) containing salt, showing as orange.

[0047] FIG. 16 depicts the coating formulated with 1,5-diphenylthiocarbazone in another preferred embodiment of the present invention that is sprayed onto a porous concrete surface (A), the dried coating peeled, as shown in (B), easily by hand from the concrete surface.

[0048] FIG. 17 depicts the selective color development in a sprayed coating on a porous concrete surface pre-contaminated with mercuric chloride (A) showing as orange, cupric chloride (B) showing as gray/green, a mixture of mercuric chloride and cupric chloride (C) showing as a combination of orange and gray, and a control coating (D) with no contaminant.

DETAILED DESCRIPTION

[0049] Various embodiments are now described with reference to the drawings. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be evident however, that such embodiment(s) may be practiced without these specific details. In the following paragraphs, the present invention will be described in detail by way of example with reference to the attached drawings. Throughout this description, the preferred embodiment and examples shown should be considered as exemplars, rather than as limitations on the present invention. As used herein, the “present invention” refers to any one of the embodiments of the invention described herein, and any equivalents. Furthermore, reference to various feature(s) of the “present invention” throughout this document does not mean that all claimed embodiments or methods must include the referenced feature(s).

[0050] Various modifications and alterations of the invention will become apparent to those skilled in the art without departing from the spirit and scope of the invention. It should be noted that steps recited in any method herein do not necessarily need to be performed in the order that they are recited. Those of ordinary skill in the art will recognize variations in performing the steps from the order in which they are recited. In addition, the lack of mention or discussion of a feature, step, or component provides the basis for claims where the absent feature or component is excluded by way of a proviso or similar claim language.

[0051] While various embodiments of the present invention have been described herein, it should be understood that they have been presented by way of example only, and not of limitation Likewise, the various diagrams may depict an example architectural or other configuration for the invention, which is done to aid in understanding the features and functionality that may be included in the invention. The invention is not restricted to the illustrated example architectures or configurations, but the desired features may be implemented using a variety of alternative architectures and configurations. Indeed, it will be apparent to one of skill in the art how alternative functional, logical or physical partitioning and configurations may be implemented to implement the desired features of the present invention. Also, a multitude of different constituent module names other than those depicted herein may be applied to the various partitions. Additionally, with regard to flow diagrams, operational descriptions and method claims, the order in which the steps are presented herein shall not mandate that various embodiments be implemented to perform the recited functionality in the same order unless the context dictates otherwise.

[0052] Although the invention is described above in terms of various exemplary embodiments and implementations, it should be understood that the various features, aspects and functionality described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead may be applied, alone or in various combinations, to one or more of the other embodiments of the invention, whether or not such embodiments are described and whether or not such features are presented as being a part of a described embodiment. Thus the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments.

[0053] Terms and phrases used in this document, and variations thereof, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. As examples of the foregoing: the term “including” should be read as meaning “including, without limitation” or the like; the term “example” is used to provide exemplary instances of the item in discussion, not an exhaustive or limiting list thereof; the terms “a” or “an” should be read as meaning “at least one,” “one or more” or the like; and adjectives such as “conventional,” “traditional,” “normal,” “standard,” “known” and terms of similar meaning should not be construed as limiting the item described to a given time period or to an item available as of a given time, but instead should be read to encompass conventional, traditional, normal, or standard technologies that may be available or known now or at any time in the future Likewise, where this document refers to technologies that would be apparent or known to one of ordinary skill in the art, such technologies encompass those apparent or known to the skilled artisan now or at any time in the future.

[0054] A group of items linked with the conjunction “and” should not be read as requiring that each and every one of those items be present in the grouping, but rather should be read as “and/or” unless expressly stated otherwise. Similarly, a group of items linked with the conjunction “or” should not be read as requiring mutual exclusivity among that group, but rather should also be read as “and/or” unless expressly stated otherwise. Furthermore, although items, elements or components of the invention may be described or claimed in the singular, the plural is contemplated to be within the scope thereof unless limitation to the singular is explicitly stated.

[0055] The presence of broadening words and phrases such as “one or more,” “at least,” “but not limited to” or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases may be absent. The use of the term “module” does not imply that the components or functionality described or claimed as part of the module are all configured in a common package. Indeed, any or all of the various components of a module, whether flow control or other components, may be combined in a single package or separately maintained and may further be distributed across multiple locations.

[0056] Additionally, the various embodiments set forth herein are described in terms of exemplary block diagrams, flow charts and other illustrations. As will become apparent to one of ordinary skill in the art after reading this document, the illustrated embodiments and their various alternatives may be implemented without confinement to the illustrated examples. For example, block diagrams and their accompanying description should not be construed as mandating a particular architecture or configuration.

[0057] The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0058] Referring now to FIG. 1, a preferred embodiment incorporating features of the invention is shown. The coating, which can be in the form of paint or other coating material, is applied to a surface, for example, a contaminated surface or a surface potentially exposed to contaminants. As the coating cures, the coating sequesters contaminants on a substrate surface. The coating formulation reacts colorimetrically to the presence of targeted contaminants to provide a visual indication of the presence of the contaminants. For example, stabilized silver nanoparticles can react with elemental mercury to form an amalgam and sequester it in the coating. Clinoptilolite in the coating traps positively charged toxic metals and sequesters them if they fit the zeolite diameter. The key to the symbols used is also shown.

[0059] A preferred embodiment of the present invention is formulated from 0.02-0.3 wt % silver dispersion (Sigma Aldrich), 83-90 weight % DeconPeel 5001, 0.2-1 wt % Triton X-100 and 10-17 weight % deionized (DI) water. DECONPEEL™ is a water based peelable coating available from General Chemical Corp Brighton, Michigan. Triton X-100 (C.sub.14H.sub.22(C.sub.2H.sub.4O)n) is a nonionic surfactant available from Union Carbide having a hydrophilic polyethylene oxide chain (on average 9.5 ethylene oxide units) and an aromatic hydrocarbon lipophilic or hydrophobic group. Embodiments incorporating features of the present invention induce a darkening of the grayish silver dispersion color applied onto polyethylene terephthalate (PET) substrates exposed to metallic Hg. The coating has sufficient mechanical strength to remain intact when stripped from a surface. By optimizing the pH of the emulsion, the colloidal stability of the silver nanoparticles is maintained to form a single phase coating.

[0060] The coating can be formulated to colorimetrically indicate the presence of metallic mercury through various configurations, for example, by direct colorimetry through color changes and/or through interaction with fine particle silver (silver dispersion), or through various known reactions. Also, sequestration of Hg can be achieved through constituents that may not have a discernible color change such as absorbers in the paint, for example clinoptilolite.

[0061] Embodiments incorporating features of the present invention can include an environmentally friendly, smart coating with embedded colorimetric indicators for contaminants. The decontamination coatings are removable. The coating indicates sequestration of contaminants visually via the color formation that occurs when color-forming chelators or ligands bind to target analytes. The present invention targets the presence of Hg(II), Cr (VI), Cd(II), Pb(II) and elemental Hg but is also applicable to other substances, particularly for waste remediation and environmental cleanup activities. The coating can be adapted for trapping radioactive materials as well.

[0062] The specific features offered by the coatings described herein include, but are not limited to: [0063] 1. Colorimetric indicators for Hg(II), Cr (VI), Cd(II), Pb(II) and reactive nanoparticles of elemental metals such as Hg in water-soluble polymers or water-based emulsions with zero to minimal volatile organic solvents—a green process that minimizes hazardous waste, [0064] 2. Curable coatings with visual indication of contaminant capture, and [0065] 3. The formulations can be cast, sprayed, dipped, rolled, painted or brushed on as liquids and cured at room temperature to form peelable freestanding films or sprayed-on as foams to trap aerosolized hazards.

[0066] Specifically, embodiments incorporating features of the present invention can utilize water-soluble polymers such as methylcellulose, polyvinyl pyrrolidone (PVP), poly(vinyl alcohol) (PVA), commercially available water-based paints (such as Deconpeel 5001, Booth Coat 5201, PlasticMask 7550) or water-based urethanes that soften when warmed above 130° F. and undergo a second order glass transition, becoming soft and pliable without actually melting. DeconPeel, Boothcoat 5201 and PlasticMask are peelable water based paints available from General Chemicals Corp, Brighton, Mich. Polyurethanes are applicable when weather-resistant coatings are required as fixatives on rough surfaces. Poly(ethylene glycol) (PEG), triethylene glycol di-2-ethylhexanoate, glycerol or sorbitol are examples of plasticizers added into the paint for ease of removal from a variety of surfaces (plastic, smooth or porous concrete walls and floors, drywall, metals and glass). Specific commercially available colorimetric agents identified in Table 2 are added to bind transition metal cations such as Hg(II), Pb (II), Cr(VI) and Cd(II) with distinct color chemistries to offer specificity.

TABLE-US-00002 TABLE 2 Commercially Available Indicators, their common names and characteristics 3,3′-Bis[N,N- bis(carboxymethyl) aminomethyl]-o- cresolsulfonephthalein tetrasodium salt (Xylenol Orange) [00001] λ.sub.max = 580 nm Hg, Pb, Cd, Au, Ni, Cu, Zn 1-(2-pyridylazo)- 2-napthol [00002] λ.sub.max = 482 nm red shifts with Hg Hg, Cu, Zn 5-(4-dimethyl- aminobenylidene) rhodanine [00003] λ.sub.max = 482 nm red shifts with Hg; Cd, Hg, Ag, Zn, Ni, Co 1,5-Diphenyl- thiocarbazone (Dithizone) [00004] λ.sub.max = 440 and 594 nm shifts to λ.sub.max = 492 nm with Hg Hg, Pb, Zn, Cu, Cd 1,5-Diphenyl carbazide (Carbazone) [00005] λ.sub.max = 540 nm Cr(VI) 3,4-Dihydroxy-9,10- dioxo-2- anthracenesulfonic acid sodium salt (Alizarin S Red) [00006] λ.sub.abs = 422 nm Cd 1 Fabretti A. C. and Peyronel G, “Rhodanine complexes of zinc(II), cadmium(II), mercury(II) and mercury(I).” Spectrochmica Acta, 1978, 34A:667-671. 2 Fabretti A. C. and Peyronel G, “Nickel(II) and Cobalt(II) Complexes of Rhodanine.” Transition Metal Chemistry, 1977, 2:207-210. 3 Paradkar R. P. and Williams R. R., “Micellar colorimetric determination of dithizone metal chelates.” Analytical Chemistry, 1994, 66: 2772-2756. 4 Chromium Hexavalent (Colormetric), EPA Method 7196A Rev 1. July 1992. 5 Ullah M. R. and Enamul Haque M., “Spectrophotometric determination of toxic elements in aqueous media.” Jounal of Chemical Engineering, IEB, 2010, ChE, 25(1): 1-12.

[0067] Colloidal silver nanoparticles (AgNPs) can be formulated into the paint and will form an amalgam with Hg sequestering the toxic metal into the paint. The agglomeration of the AgNPs upon binding to Hg can also be indicated by a color change similar to color changes in size dependent colloidal dispersions of silver or gold. Stabilizing agents such as non-ionic surfactants, for example Triton X-100 and Tween-20 can be added to the formulations to improve particle distribution. Ionic surfactants, such as dodecyl sulfonate (DDS), can be used to stabilize the AgNPs in the formulation. The stabilizing agents and ionic surfactants used in the formulation aid in drawing the elemental mercury into the aqueous coating to sequester it. The coatings disclosed herein can be sprayed to trap airborne contaminants such as elemental mercury. Since airborne mercury is reported to have 95% elemental Hg and 5% in reactive form (Hg.sup.2+), any observed color change will be indicative of the presence of mercury. The formulation also uses a small amount of zeolite (clinoptilolite—a natural zeolite comprising a microporous arrangement of silica and alumina tetrahedral) to trap toxic metals such as mercury, cadmium, lead and arsenic. Being a water-based coating, the ionic metal (M.sup.n+) species will migrate into the coating away from the contaminated surface. Upon curing the coating (from about 16 up to about 48 hours), the binding event will be signaled by a visual color change indicating the presence of the (M.sup.n+) in select regions of the coating. The color development in the coatings can be calibrated to a visible detection limit using a standard color wheel to quantify the sequestered contaminant. A wet thickness from about 0.25 mm to 0.7 mm of the coating is applied by spraying or doctor blading the coating on to the surface. The coating is then cured at ambient room temperature for up to about 48 hours, preferably 24-48 hours depending on the specific formulation and surface type.

[0068] One example of a coating incorporating features of the invention is Formulation 1A comprising 0-4% by weight Booth Coat 5201, 5-15 weight % of 1,5-diphenylthiocarbazone (Dithizone) in reagent alcohol, 0-1.5% by weight of clinoptilolite and 79-90% by weight of Deconpeel 5001. The use thereof is shown in FIG. 3, FIG. 4, FIG. 5 and FIG. 6. A second example is Formulation 1B that comprises 0-4% by weight Booth Coat 5201, 10-15 weight % of 1-(2-pyridylazo)-2-napthol in 95:5 deionized water, Triton X-100 and 79-90% by weight of Deconpeel 5001, the use thereof shown in FIG. 7. A third example is coating Formulation 1C that comprises 0-4% by weight Booth Coat 5201, 10-15 weight % of Rhodanine in 80:20 ethanol/water with 20-30% Triton X-100 and 70-85% Deconpeel 5001, the use thereof being shown in FIG. 8.

[0069] A fourth example comprises water-soluble polymers such as methylcellulose or Methocel® (MC) (Mw ˜41,000) and polyvinylpyrrolidone (Mw ˜36,000-55,000) (PVP) in Formulation 2. The new peelable coating formulation comprises a 5:1 mixture ratio with 2-6 weight % MC and 1-3% PVP. These coatings can be applied to various structures, for example, concrete brick, PVC, glass and steel. When dry, the coatings can be peeled from the substrates. The coatings have sufficient mechanical strength to remain intact when stripped from the surfaces, with the possible exceptions of some varieties which have an increased adherence to concrete brick. Viscosity measured by a Brookfield HBVT viscometer ranges from 2% MC+3% PVP ˜400-600 cP; 4% MC+3% PVP ˜6000-8000 cP, and 6% MC+3% PVP ˜26000-28600 cP respectively. A fifth embodiment is Formulation 3A comprising 70-85 weight % PlasticMask 7550, 0-1.5 weight % clinoptilolite, 15-20 weight % alpha terpineol, 0.032-0.128 weight % 1,5 diphenylthiocarbazone (Dithizone), 0.1-2.0 weight % Triton X-100 and 3-6% water. Use thereof is illustrated in FIG. 10, FIG. 11, FIG. 12 and FIG. 13 and FIG. 15.

[0070] A sixth example is Formulation 3B comprising 70-85 weight % PlasticMask 7550, 0-1.5 weight % clinoptilolite, 15-20 weight % alpha terpineol, 0.032-0.128 weight % 1,5-dephenylcarbazide, 0.1-2 weight % Triton X-100 and 3-6 weight % water; FIG. 14 shows such composition for detection of Cr(VI).

[0071] Dried coating thickness can vary depending on the formulation used, number of layers applied and the substrate type. Table 3 lists coating thickness measurements based on these variables for the various formulations. The resulting coatings are peelable using moderate force.

[0072] FIG. 2 depicts an example test protocol used to validate the contamination efficiency of the coatings. The chromogenic indicator used is Dithizone applied to Formulation 3. Mercuric chloride was used as the source for Hg(II) ions to develop a standard curve. The concentrations used in establishing the standard curve ranges from 2 μg to 10 μg with 10% intervals. 0.1 μmol dithizone in acetone was prepared, which equals to 25.6 μg Dithizone in the reaction volume. The standard curve was generated through direct reaction of Hg (II) with Dithizone in acetone. Hg (II)-Dithizone complex can be immediately measured using a UV-visible spectrometer. Glass Petri Dishes can be used as test coupons; 0.05 mL of water and 1 M HgCl.sub.2 stock solution can be deposited on the surface separately and allowed to dry for 24 hours before applying the coating. 2 g of coating formulation can then be deposited onto the petri dishes. After the coating is sufficiently dried, usually 24 hours, it can be removed and color changes inspected and photographed. Pink color formation is visible to the eye where Hg (II) is present.

[0073] After peeling away the smart coating, the surface can be rinsed with 1 mL of 0.1 μmol Dithizone indicator solution in acetone, collected in a beaker and then transferred into cuvettes. The collected rinsates can be characterized by UV/VIS absorption spectroscopy. A calibration curve can constructed using measurements made from serial dilutions of the stock solutions and a regression function generated from standard curve can be used to calculate the detectable residual metal ion concentrations on the test coupon surface after the coating has been stripped.

EXAMPLE 1

Detection and Peelability Testing

[0074] Testing was conducted using 0.05 mL of two concentrations of metal ion solutions (0.01 M and 0.05 M solutions of Hg.sup.2+, Cu.sup.2+ and Ni.sup.2+) drop cast on various substrates (porous cement brick, PVC, stainless steel and painted drywall). Although testing was conducted for these contaminants, it should not be concluded that the present invention is limited to these contaminants. The calculated weights for the metal ions are shown in Table 4. Coating Formulation 1A was applied to these metal ion contaminated substrates. Referring to FIG. 3, FIG. 4, FIG. 5 and FIG. 6, the images show the colorimetric reaction of the present invention to various metal contaminants. The figures also depict the coating technology application and removal from porous cement brick, PVC, stainless steel and painted drywall.

TABLE-US-00003 TABLE 4 Calculated Weights of Dried Metal from 0.05 mL Solutions Calculated Weight of Dried Metal from 0.05 cc Solutions (mg) Concentration (M) Hg Cu Ni 0.01 0.1003 0.0318 0.0293 0.05 0.5015 0.1589 0.1467

[0075] Testing was also conducted using 0.05 mL of two concentrations of metal ion solutions (0.01 M and 0.05 M solutions of Hg.sup.2+, Cu.sup.2+ and Ni.sup.2+) drop cast on painted drywall. Coating Formulation 1B was applied to these metal ion contaminated substrates. Referring to FIG. 7, the image shows the colorimetric reaction of the present invention to various metal contaminants. The visible limit of detection (LOD) was 15.92 μg/cm.sup.2 for Hg(II), 0.25 μg/cm.sup.2 for Cu(II) and 0.59 μg/cm.sup.2 for Ni(II). Coating Formulation 1C was applied to these metal ion contaminated substrates. Referring to FIG. 8, the image shows the colorimetric reaction of the present invention to various metal contaminants. The visible limit of detection (LOD) was 63.79 μg/cm.sup.2 for Hg(II), 2.55 μg/cm.sup.2 for Cu(II) and 93.46 μg/cm.sup.2 for Ni(II). The visible LOD for coating Formulation 1A can be inferred from FIG. 9 as follows: 1.02 μg/cm.sup.2 for Hg(II), 0.25 μg/cm.sup.2 for Cu(II) and 18.72 μg/cm.sup.2 for Ni(II).

[0076] Testing was also conducted using aqueous potassium dichromate as a source of Cr(VI) and Cadmium sulfate as a source of Cd(II) and applied to a painted dry wall. Formulation 3B showed a deep purple color against a pale pink background paint color for Cr (VI) tested at concentrations of 5 and 0.5 μg/cm.sup.2. Formulation 3A shows a tan-pink color developed against a tan background to indicate the presence of Cd(II) concentration at 3.14 mg/cm.sup.2.

[0077] Testing was also conducted with Formulation 3A using various soluble and insoluble mercury compounds (mercuric chloride, mercuric sulfate, mercuric iodide, mercuric bromide, mercuric oxide and mercuric sulfide) aqueous solutions or suspensions applied to a painted drywall. The visible LODs could be inferred as ˜40 ng/cm.sup.2 for mercuric sulfate, ˜4 ng/cm.sup.2 for mercuric oxide and ˜40 ng/cm.sup.2 for mercuric chloride from FIG. 10 and ˜4 μg/cm.sup.2 mercuric sulfide and ˜4 ng/cm.sup.2 each for mercuric bromide and mercuric iodide from FIG. 11.

[0078] Testing was also conducted with Formulation 3A using mercuric chloride applied to a painted drywall and ranging in concentration from 40 ug/cm.sup.2 to 4 ng/cm.sup.2. Dried coatings were placed in room ambient and observed for color fading over time at the following intervals (0, 4, 18 and 32 days). The Visible LOD remained unchanged at 40 ng/cm.sup.2 for all the observed time periods shown in FIG. 12.

[0079] Testing was also conducted with Formulation 3A applied to elemental mercury contaminated soil from a field test site (Y-12 complex) in the form of samples provided by the Oak Ridge National Laboratory. A known quantity of the contaminated soil sample was placed in a Petri Dish and a known quantity of Formulation 3A was applied over the soil. FIG. 13 shows the pink coloration that developed in different regions of the dried paint. The sequestered elemental mercury and any oxidized forms in the paint complex with Dithizone to form the pink color observed.

[0080] Testing was also done to fine tune Formulation 3A for spray application and peel ability from concrete walls. A Wagner Power Paint Pro airless spray gun was used for this test with formulation viscosities ranging from 7000-10000 centipoise (cP). Dried film thickness for one layer ranged from ˜0.2-0.35 mm and was ˜0.5-0.75 mm for a 2 layer coating by varying the viscosities and spray conditions. FIG. 16 shows an example of a 2-layer sprayed coating partially peeled from the porous concrete block. The coating is peel able by hand with moderate force.

[0081] Testing was also done to investigate the ability of spray applied Formulation 3A to show color formation in the porous concrete wall that is contaminated with mercuric chloride, cupric chloride, a mixture of cupric chloride and mercuric chloride and an uncontaminated surface (control). It can be inferred from FIG. 17a that a pink color develops in the paint in the presence of Hg(II) while FIG. 17-(b) shows a blue color develops in the presence of Cu(II). Both colors are visible in FIG. 17-(c) when both contaminants are present on the concrete surface while no additional color develops in the control coating (FIG. 17-(d)).