Self-indicating colorimetric response materials for removal and sensing of toxic chemicals and narcotics
Inventors
Soliz, Jennifer R • Emge, Darren K • Pardoe, Ian J • Peterson, Gregory W
Assignees
United States Department of the Army
Publication Number
US-11402322-B1
Publication Date
2022-08-02
Expiration Date
2038-04-27
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Abstract
Processes, compositions, and sensors for sensing a variety of toxic chemicals based on colorimetric changes. Exemplary process for sensing a toxic chemical includes contacting a toxic chemical, or byproduct thereof, with a sorbent that includes a porous metal hydroxide or a porous mixed-metal oxide/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 is determined to thereby detect exposure to, or the presence of, the toxic chemical or byproduct thereof.
Core Innovation
The invention concerns compositions, methods, and devices for monitoring the presence or absence of hazardous chemicals in the environment. It specifically provides porous sorbents, consisting of metal oxides and metal hydroxides, for both the removal of toxic chemicals and the detection thereof via self-indicating color/spectral changes. These self-indicating colorimetric response materials allow sensing of toxic chemicals in liquid, solid, and vapor phases, enabling real-time detection through visual or spectral changes.
The invention addresses the problem in air purification, particularly in military and industrial settings, where filters using activated carbons have limited lifetimes and their capacity degrades due to environmental contaminants before a toxic chemical event occurs. Existing end-of-service-life indicators (ESLIs) have shortcomings such as poor sensing of reactive gases and insufficient reactivity. Residual life indicators (RLIs) also fail to accurately determine the effects of acidic or acid-forming contaminants on filter life.
To overcome these challenges, the invention introduces processes and materials that allow sensitive, selective, and robust colorimetric responses to toxic chemicals, including chemical warfare agents and narcotics. It utilizes porous metal hydroxides or mixed-metal oxide/hydroxide sorbents combined with transition metal reactants that react with toxic chemicals or their byproducts, yielding a measurable colorimetric change. The sorbents are adaptable in multiple forms, including powders, films, and wearable sensors, and can be incorporated into in-service filter systems for real-time monitoring of exposure and filter residual life.
Claims Coverage
The patent contains one independent claim that outlines a process for sensing toxic chemicals using specific sorbents and detecting colorimetric changes, highlighting multiple inventive features.
Sorbent composition for toxic chemical sensing
A sorbent comprising a porous mixed-metal oxide/hydroxide selected from silicon-aluminum oxides/hydroxides, iron-silicon-aluminum oxides/hydroxides, silicon-aluminum-titanium oxides/hydroxides, and silicon-aluminum-titanium-phosphorus oxides/hydroxides with defined metal ratios.
Incorporation of transition metal containing reactants
Inclusion of transition metal salts, acetates, nitrates, sulfides, chlorides, oxides, or oxyhydroxides of metals like chromium, cobalt, copper, iron, manganese, nickel, or lanthanides in the sorbent to react with toxic chemicals or byproducts.
Detection of colorimetric change upon exposure
Determining a difference between pre-exposure and post-exposure colorimetric states of the sorbent by visible color or color spectra change across wavelengths from infrared to ultraviolet.
Applicability to various toxic chemicals and exposure types
Capability of sensing chemical warfare agents including G class, V class, blistering, organophosphate agents, narcotics like fentanyl, and adaptability to solid, liquid, aerosol, or vapor exposure.
Optional inclusion of porous polymer in sorbent
Sorbent may optionally contain 10 to 50 weight percent of a porous polymer such as poly(methyl methacrylate) to form composite films suitable for sensing applications.
Overall, the claims define a process utilizing specialized porous mixed-metal oxide/hydroxide sorbents combined with transition metal reactants to detect toxic chemicals across multiple phases by monitoring colorimetric changes, including embodiments using polymer composites and covering a broad range of hazardous substances including chemical warfare agents and narcotics.
Stated Advantages
Provides sensitive and robust colorimetric responses to a variety of toxic chemicals and their byproducts.
Enables real-time detection across different physical states (solid, liquid, vapor) of toxic chemicals.
Applicable for use in end-of-service-life indicators and residual life indicators to monitor filter capacity and lifetime.
Allows incorporation into diverse formats including films, wearable sensors, and chemical detectors for practical deployment.
Offers improved detection especially for acidic/acid-forming and oxidizable gases where existing technologies fall short.
Documented Applications
Monitoring presence or absence of hazardous chemicals in environmental air purification systems specifically for military, first responders, and industrial workers.
Incorporation into individual and collective protection filtration systems as end-of-service-life and residual life indicators to alert users when filter replacement is needed.
Use in wearable self-indicating colorimetric chemical sensors and films for toxic chemical detection via optical, spectral, and electronic sensing.
Application in chemical detection devices, including optical and spectral chemical sensors, capable of detecting chemical warfare agents, industrial toxic chemicals, and narcotics like fentanyl.
Deployment in filter housings with sorbents located to detect breakthrough exposure indicating filter exhaustion in situ.
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