System for electrochemical detection of chlorate explosives

Inventors

Dressick, Walter J.Trammell, Scott A.Shriver-Lake, Lisa C.

Assignees

US Department of Navy

Publication Number

US-10048221-B1

Publication Date

2018-08-14

Expiration Date

2036-08-11

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Abstract

A method of detecting chlorate in soil includes contacting soil wetted with a solvent containing an electrically conductive salt with an electrode comprising layers of vanadium-substituted phosphomolybdate alternating with layers of para-rosaniline, and performing voltammetry with the electrode, wherein a catalytic reduction current indicates a likelihood of the presence or absence of chlorate in the soil. A system includes a potentiostat operably connected to the electrode and in communication with hardware and software sufficient to produce an output indicating a chlorate level in soil.

Core Innovation

The invention provides a method and system for detecting chlorate in soil using an electrode composed of alternating layers of vanadium-substituted phosphomolybdate and para-rosaniline. The electrode is contacted with soil wetted by a solvent that contains an electrically conductive salt, and voltammetry is performed. The catalytic reduction current measured indicates the likelihood of the presence or absence of chlorate in the soil. This detection can be accomplished without the need to exclude oxygen or use strong acid, making it suitable for ambient field conditions.

The system includes a potentiostat connected to the electrode and computer hardware and software configured to produce output indicating chlorate levels in soil. The electrode is prepared via layer-by-layer deposition producing a composite film that is stable over weeks. The electrode operates robustly and selectively under ambient conditions without interference from oxygen or other common explosives such as TNT, enabling rapid, field-deployable detection of chlorate explosives.

The problem being solved is the lack of reliable field detection methods for chlorate-based explosives, which pose serious hazards in conflict zones. Existing methods either require complex lab equipment like ion exchange chromatography with mass spectrometry, or spectrophotometric methods that suffer from interference by other chlorine species. Electrochemical methods have promise but previous electrodes, such as mercury-based ones, are not suitable for field use, and oxygen interference limits analysis. Thus, there is a need for a portable, rugged, selective, and sensitive chlorate sensor operable in ambient, oxygen-containing environments directly on soil samples.

Claims Coverage

The patent contains one independent claim that defines a system for chlorate analysis with several inventive features.

Electrode comprising alternating layers of vanadium-substituted phosphomolybdate and para-rosaniline

The system uses an electrode formed by layers of vanadium-substituted phosphomolybdate alternating with layers of para-rosaniline to detect chlorate electrochemically.

Potentiostat operably connected to the electrode for voltammetry

The system includes a potentiostat connected to the electrode to perform voltammetry, producing a catalytic reduction current related to chlorate levels.

Computer hardware and software for chlorate level output

The system includes computer hardware and software communicating with the potentiostat to process voltammetric data and output an indication of the chlorate level in soil contacting the electrode.

The claim covers a system integrating a specific layered electrode, potentiostat for electrochemical measurement, and computing elements configured to detect and indicate chlorate levels in soil samples via voltammetry.

Stated Advantages

Portable, small, and lightweight, including the potentiostat and electronics.

Operates without interference by oxygen, enabling field use without degassed solutions.

Selective and does not respond to common explosives such as TNT and RDX present in the environment.

Rugged composite film adheres well to the electrode substrate ensuring durability.

Easy preparation by simple dip-coating, producing uniform and reproducible active films.

Stable activity for catalyzed chlorate electroreduction retained for at least 8 weeks dry storage at room temperature.

Documented Applications

Detection of chlorate in soil samples for confirming presence of improvised explosive devices (IEDs) or manufacturing sites.

Field deployment including use by personnel or from unmanned aerial vehicles (UAVs) for remote surveillance and analysis.

Rapid on-site testing under ambient oxygen without requiring strong acidification or oxygen removal.

Integration into systems with potentiostat, solvent reservoirs, and wireless data transmission for remote sensing workflows.

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