Self-indicating zirconium hydroxide and other porous metal hydroxides incorporating additional metals, metal oxides, and/or metal salts for toxic chemical removal and sensing
Inventors
Peterson, Gregory W • Rossin, Joseph A • Soliz, Jennifer R • Killops, Kathryn L.
Assignees
United States Department of the Army
Publication Number
US-10261022-B1
Publication Date
2019-04-16
Expiration Date
2035-06-18
Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
Abstract
Processes for sensing a variety of toxic chemicals and/or processes for determining the residual life of a filter or filtration system are provided. Exemplary process for sensing a toxic chemical include contacting a toxic chemical, or byproduct thereof, with a sorbent that includes a porous metal hydroxide and a transition metal reactant suitable to react with a toxic chemical or byproduct thereof. The sorbent is contacted with the toxic chemical or byproduct thereof for a sampling time. A difference between a post-exposure colorimetric state of the sorbent and a pre-exposure colorimetric state of the sorbent or control is determined to thereby sense exposure to, or the presence of, the toxic chemical or byproduct thereof.
Core Innovation
The invention provides processes for sensing a variety of toxic chemicals and determining the residual life of a filter or filtration system using sorbents comprising porous metal hydroxides and transition metal reactants. The processes involve contacting a toxic chemical or its byproduct with the sorbent during a sampling time and determining a difference between the post-exposure and pre-exposure colorimetric states of the sorbent, thus sensing exposure to or presence of the toxic chemical.
The sorbent includes porous metal hydroxides such as hydroxides of silicon, aluminum, magnesium, cobalt, copper, zinc, titanium, zirconium, vanadium, chromium, manganese, nickel, calcium or combinations thereof, and transition metal reactants including salts, oxides, or oxyhydroxides of cobalt, copper, iron, manganese, or nickel. The sorbent may be combined with film-forming polymers and configured within or on filters to provide colorimetric changes that function as end-of-service-life indicators (ESLI) or residual life indicators (RLI) for filters.
The problem addressed arises from limitations in existing filters, such as activated carbons, that degrade capacity due to interaction with environmental contaminants before exposure to toxic chemicals. Current ESLI and RLI technologies have shortcomings in sensing reactive or acidic gases and in determining residual life accurately. Therefore, new processes and material compositions are needed for sensitive and accurate detection and quantification of acidic, acid-forming, oxidizable, and other toxic chemicals to monitor filter life and safety.
Claims Coverage
The patent discloses one independent claim covering a filtration system with integrated sensing capabilities through a sorbent incorporating specific material compositions and configurations.
Filter system with integrated residual life indicator
A filter/filtration system comprising a filter housing and filtration material, with a sorbent consisting of a porous metal hydroxide and a transition metal reactant that reacts with toxic chemicals or byproducts to exhibit a change in colorimetric state after exposure.
Sorbent positioning within filter housing
The sorbent is located distal from an exposure surface within the filter housing, enabling detection of breakthrough toxic chemicals indicating end of filter lifetime.
Integrated detection capability
The system optionally includes a detector or a part thereof within the filter housing, in electromagnetic contact with the sorbent to monitor the colorimetric state.
Porous metal hydroxide composition
The porous metal hydroxide in the sorbent comprises hydroxides of metals such as silicon, aluminum, magnesium, cobalt, copper, zinc, titanium, zirconium, vanadium, chromium, manganese, nickel, calcium, or mixtures thereof.
Transition metal reactant composition
The transition metal reactant comprises salts, oxides, or oxyhydroxides of cobalt, copper, iron, manganese, or nickel.
Specific porous metal hydroxide types
Porous metal hydroxides specifically include aluminum hydroxide, iron hydroxide, zinc hydroxide, silicon hydroxide, magnesium hydroxide, zirconium hydroxide, cobalt hydroxide, copper hydroxide, titanium hydroxide, vanadium hydroxide, chromium hydroxide, manganese hydroxide, nickel hydroxide, calcium hydroxide, iron-silicon hydroxide, iron-aluminum hydroxide, and silicon-aluminum hydroxide.
Specific transition metal reactants
Transition metal reactants include KMnO4, CoCl2, Co(NO3)2, CoSO4, Co(C2H3O2), CuSO4, CuBr, CuCl2, Cu(NO3)2, NiCl2, FeCl2, FeCl3, or FeSO4.
Transition metal reactant concentration
The transition metal reactant is present at a concentration ranging from 1 to 50 weight percent in the sorbent.
The claims collectively cover a filtration system designed with sorbents composed of porous metal hydroxides and transition metal reactants, configured within the filter housing to provide visible or instrumental colorimetric changes upon exposure to toxic chemicals, thereby serving as integrated residual life or end-of-service-life indicators.
Stated Advantages
Provides sensitive and robust detection of acidic, acid-forming, and oxidizable toxic chemicals and byproducts through a visible or measurable colorimetric change.
Offers reliable and reproducible detection of toxic chemicals and quantification of exposure amount via shifts in spectral properties.
Facilitates rapid determination of residual filter life or end-of-service-life, improving safety and operational awareness.
Enables integration within filters as visual indicators or via embedded detectors coupled to alarms for user notification.
Documented Applications
Use in respirators and collective protection filtration systems as end-of-service life indicators (ESLI) and residual life indicators (RLI).
Application in detecting toxic industrial chemicals, chemical warfare agents, battlefield contaminants, and industrial hazardous gases.
Use in monitoring environmental exposure to acidic/acid-forming and oxidizable gases within filter materials to determine filter breakthrough and lifetime.
Interested in licensing this patent?