Removable smart sequestration coatings for hazardous metals
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.
1. A coating formulation for application to a surface, said coating formulation including one or more colorimetric indicators, the one or more colorimetric indicators exhibiting metal specific color changes in the presence of metallic contaminants on said surface comprising 70-85 weight % of water soluble plastics, water-based paints or water-based urethanes, 0-1.5 weight % of a zeolite, 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.
2. The coating formulation of claim 1 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.
3. The coating formulation of claim 1 wherein the film is cured for 24 to 48 hours at room temperature or for lesser time at elevated temperatures.
4. The coating formulation of claim 1 , said film peeled from the surface by mechanical means with moderate force.
5. The coating formulation of claim 1 where the dried peeled film has a thickness from 0.2-0.35 mm for a single layer and 0.5-0.75 mm for two-layer spray applied coatings.
6. The coating formulation of claim 1 wherein the zeolite is Clinoptilolite.
7. A coating formulation for application to a surface, said coating formulation including one or more colorimetric indicators, the one or more colorimetric indicators exhibiting metal specific color changes in the presence of metallic contaminants on said surface comprising 70-85 weight % of water soluble plastics, water-based paints or water-based urethanes, 0-1.5 weight % of a zeolite, 15-20 weight % alpha terpineol, 0.032-0.128 weight % of 1,5-diphenylcarbazide, 0.1-2 weight % of a surfactant and 3-6 weight % water 17.
8. The coating formulation of claim 7 wherein the film shows a color change from pale pink to localized regions of purple in the presence of Cr(VI) species sequestered in the coating.
9. The coating formulation of claim 7 wherein the film is cured for 24 to 48 hours.
10. The coating formulation of claim 7 , said film peeled from the surface by mechanical means with moderate force.
11. The coating formulation of claim 7 wherein the zeolite is Clinoptilolite.