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-11385169-B1
Publication Date
2022-07-12
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 provides processes, compositions, and devices for sensing a variety of toxic chemicals through colorimetric changes. It employs sorbents composed of porous metal hydroxides or porous mixed-metal oxides/hydroxides combined with transition metal reactants that react with toxic chemicals or their byproducts. Detection of toxic chemicals is accomplished by comparing the colorimetric state of the sorbent before and after exposure, allowing identification of exposure to toxic chemicals or their byproducts in solid, liquid, or vapor phases.
The problem addressed arises from the limited lifetime and degraded capacity of current filtration systems, particularly for military, first responders, and industrial workers, due to interaction with environmental contaminants such as SOx, NOx, and hydrocarbon vapors, which diminish filter effectiveness before a toxic chemical event occurs. Existing end-of-service-life indicators (ESLI) and residual life indicators (RLI) have shortcomings including poor sensing of reactive gases and inability to accurately determine the effects of acidic or acid-forming contaminants on residual filter life. Therefore, there is a need for new processes and materials that provide sensitive, robust, and accurate detection and quantification of toxic and acid-forming chemicals to monitor residual filter life and toxic chemical presence.
The invention describes the use of porous metal hydroxides, such as zirconium hydroxide, combined with transition metal salts, oxides, nitrates, or oxyhydroxides of cobalt, copper, iron, manganese, or nickel, which exhibit self-indicating colorimetric responses upon exposure to toxic chemicals or their byproducts. These sorbents can be incorporated into films, wearable sensors, detection devices, or filtration systems as end-of-service-life or residual life indicators. The porous nature and metal composition enable absorption and reaction with various toxic chemicals including chemical warfare agents, narcotics such as fentanyl, and chemicals with thiolate, chloride, fluoride, or cyanide leaving groups, thereby providing visible or spectral changes upon exposure for real-time and reliable sensing.
Claims Coverage
The patent includes one independent claim focused on a sorbent composition for sensing toxic chemicals. The independent claim highlights several inventive features regarding sorbent composition, transition metal reactants, and application.
Porous mixed-metal oxide/hydroxide sorbent composition
The sorbent comprises a porous mixed-metal oxide/hydroxide selected from silicon-aluminum oxide/hydroxide; iron-silicon-aluminum oxide/hydroxide; silicon-aluminum-titanium oxide/hydroxide; and silicon-aluminum-titanium-phosphorus oxide/hydroxide, with defined metal-to-metal ratios (e.g., silicon-to-aluminum from 3 to 1,000, silicon-to-titanium from 2 to 500, titanium-to-phosphorus from 1 to 500).
Transition metal containing reactant integrated in sorbent
The sorbent includes a transition metal containing reactant configured to react with toxic chemicals or byproducts thereof, wherein the reactant comprises salts, acetates, nitrates, sulfides, chlorides, oxides, or oxyhydroxides of chromium, cobalt, copper, iron, manganese, nickel, or lanthanides at concentrations ranging from 1 to 90 weight percent.
Capability for reaction with toxic chemicals across different exposure phases
The sorbent is configured so the toxic chemical reacts with the surface of the transition metal containing reactant inside the pore structure of the porous mixed-metal oxide/hydroxide, with toxic chemicals contacted via solid, liquid, aerosol, or vapor exposure.
Applicability to hazardous substances including chemical warfare agents and narcotics
The sorbent is suitable for sensing chemical warfare agents including G-class, V-class, blistering agents, organophosphates, as well as narcotics and opioids such as fentanyl, carfentanil, and remifentanil and their byproducts.
Incorporation with porous polymers
The sorbent can be combined with a porous polymer, such as poly(methyl methacrylate), comprising 10 to 50 weight percent of the sorbent polymer composite.
The independent claim covers a sorbent comprising a defined porous mixed-metal oxide/hydroxide and transition metal reactant combination with specific metal ratios and compositions configured for reactive sensing of toxic chemicals, capable of functioning across various exposure phases, including chemical warfare agents and narcotics, and having the capability to be integrated into polymer-based films.
Stated Advantages
Provides sensitive and robust colorimetric detection of a variety of toxic chemicals and byproducts in solid, liquid, and vapor phases.
Allows determination of residual life or end-of-service-life of filters by detecting exposure to acidic and acid-forming contaminants.
Improves reliability and reproducibility of toxic chemical detection versus existing ESLI and RLI technologies with poor sensitivity to reactive gases.
Enables integration into wearable sensors, films, chemical detection devices, and filtration systems for real-time visual or instrumental monitoring.
Documented Applications
Use in air purification filtration systems as end-of-service-life indicators (ESLI) or residual life indicators (RLI) for military, first responders, and industrial workers.
Incorporation into films, wearable chemical sensors, and chemical detection devices for sensing toxic chemicals including chemical warfare agents and narcotics.
Application in removal and sensing of toxic chemicals in liquid, solid, and vapor phases via colorimetric responses.
Use in respirators and collective protection filters to alert users to filter change-out necessity.
Deployment within filter housings for in situ detection of breakthrough or toxicity exposure across filter beds.
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