Hydrophobic Room Temperature Ionic Liquid Research Articles

Evaluation of short alkyl chain modified [DBU][TFSI] based ionic liquids as supercapacitor electrolytes

The need of new electrolytes with wide electrochemical window, good stability and conductivity has promoted novel ionic liquids (ILs) as new solutions for supercapacitors. In this work, four hydrophobic room temperature ionic liquids based on organic superbase-derived cations and Trifluoromethanesulfonimide (TFSI) anion were synthetized. The structures of the novel ILs were analyzed, characterized and their performance as a supercapacitor electrolyte was evaluated. The ILs have high decomposition temperatures of up to 490 °C and electrochemical window up to 4.8 V. It was found that there was an optimal chemical structure providing the best stability and operational potential window coupled with moderate conductivity. The IL with the shortest alkyl chain structure provided the highest conductivity but suffered from instability. The performance of the ILs with longer alkyl chains was hindered by lower conductivities and, in the case of the largest chemical structures, also by reduced cyclic stabilities in open air. However, the ionic liquid with moderate alkyl chain length was found to be stable even in open air providing decent conductivity, which can be utilized in future research to develop other hydrophobic ionic liquids suitable as supercapacitor electrolytes.

Transport and Energetics of Carbon Dioxide in Ionic Liquids at Aqueous Interfaces.

A major hurdle in utilizing carbon dioxide (CO2) lies in separating it from industrial flue gas mixtures and finding suitable storage methods that enable its application in various industries. To address this issue, we utilized a combination of molecular dynamics simulations and experiments to investigate the behavior of CO2 in common room-temperature ionic liquids (RTIL) when in contact with aqueous interfaces. Our investigation of RTILs, [EMIM][TFSI] and [OMIM][TFSI], and their interaction with a pure water layer mimics the environment of a previously developed ultrathin enzymatic liquid membrane for CO2 separation. We analyzed diffusion constants and viscosity, which reveals that CO2 molecules exhibit faster mobility within the selected ILs compared to what would be predicted solely based on the viscosity of the liquids using the standard Einstein-Stokes relation. Moreover, we calculated the free energy of translocation for various species across the aqueous-IL interface, including CO2 and HCO3-. Free energy profiles demonstrate that CO2 exhibits a more favorable partitioning behavior in the RTILs compared to that in pure water, while a significant barrier hinders the movement of HCO3- from the aqueous layer. Experimental measurement of the CO2 transport in the RTILs corroborates the model. These findings strongly suggest that hydrophobic RTILs could serve as a promising option for selectively transporting CO2 from aqueous media and concentrating it as a preliminary step toward storage.

Hydrophobicity-Dependent Heterogeneous Nanoaggregates and Fluorescence Dynamics in Room-Temperature Ionic Liquids.

The hydrophobicity of room-temperature ionic liquids (RTILs) has been shown to have a very significant effect on the optical and structural properties of and in RTILs. The average excited state lifetime of neat RTILs has been shown to be increasing with increasing hydrophobicity of the RTILs. By employing pico-nanosecond-based fluorescence anisotropy decay, the volume of the nanoaggregates in neat RTILs have been calculated. The volume of these nanoaggregates have been shown to be decreasing with increase in hydrophobicity of the RTILs. Thus, hydrophobicity has been shown to have an important role, i.e., hydrophobicity can be used as a handle to tune the properties of RTILs as designer solvents. Moreover, the excited-state lifetime of red-emitting fluorophores, i.e., whose fluorescence emission is not perturbed by the inherent emission of RTILs, has been shown to increase with the increasing hydrophobicity of the RTILs. Highly hydrophobic RTILs have been shown to exhibit positive deviation and highly hydrophilic RTIL has been shown to exhibit negative deviation from the linear correlation between average solvation time (τs) versus viscosity/temperature (η/T).

Ethyl-, vinyl- and ethynylcyanoborates: room temperature borate ionic liquids with saturated and unsaturated hydrocarbon chains.

Ethyl-, vinyl- and ethynyltricyano and dicyanofluoroborates were prepared on a gram scale from commercially available potassium trifluoroborates and trimethylsilylcyanide. Salt metathesis resulted in the corresponding EMIm-salts that are hydrophobic room-temperature ionic liquids (RTILs). The new RTILs exhibit unprecedented large electrochemical windows in combination with high thermal stabilities, low dynamic viscosities and high specific conductivities. These properties make them promising materials, especially for electrochemical applications.

Room temperature ionic liquid based extraction and recovery of Rifampicin from water and its mechanistic study

An attempt has been made to develop a fast, efficient and eco-friendly process for extraction of drug; Rifampicin (RF) from its aqueous solutions using room temperature ionic liquids (RTILs). RTILs viz. 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][NTf2]), 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) and 2-Hydroxyethyl-trimethylammonium L-(+)-lactate ([(C2H4OH)-(CH3)3N][Lactate])/CL have been applied for removal of RF. Factors affecting removal of this contaminant from its aqueous solution such as effect of hydrophilicity/hydrophobicity of RTILs, concentration of used RTILs and effect of pH of drug solution have been studied to investigate mechanism of extraction process. Partition coefficient, of RF between RTILs and aqueous phases as well as its extraction efficiency E% have been calculated and analyzed. Results showed that hydrophobic RTILs; [BMIM][PF6] and [EMIM][NTf2] are more efficient in extraction of RF from its aqueous solutions in just 1 minute as compared to hydrophilic RTILs; [BMIM][BF4] and [(C2H4OH)-(CH3)3N][Lactate].

Solvent extraction of lithium ions using benzoyltrifluoroacetone in new solvents

This work studies the solvent extraction of lithium ions from alkaline aqueous solutions by chelating agent 3-benzoyl-1,1,1-trifluoroacetone (HBTA). To develop a more eco-friendly extraction system for lithium than currently used, various hydrophobic room-temperature ionic liquids were investigated as diluents. The influence of several experimental parameters on lithium extraction was examined, including aqueous phase pH, the nature of lithium counter-ion, extractant concentration, the addition of electrically neutral co-extractant.It was found that contrary to the traditional extraction systems with molecular diluents, HBTA alone dissolved in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid extracts efficiently lithium ions from the aqueous solution. The addition of co-extractant, tri(n-octyl)phosphine oxide (TOPO) to HBTA did not result in a synergetic effect. To confirm the mechanism of lithium extraction by HBTA dissolved in ionic liquid (IL), the measurements of IL constituent ions and deprotonated HBTA concentrations in the equilibrium aqueous phase were carried out. Analysis of the results suggests that an electrically neutral lithium-HBTA extractant complex is extracted into the IL phase.The system combining HBTA extractant and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid has high selectivity for lithium over sodium but poor selectivity over calcium. We have shown also that a high stripping ratio can be obtained using relatively concentrated aqueous solutions of hydrochloric acid. Finally, it was found that the use of some deep eutectic solvents as diluents is much less efficient compared with ILs.

Solvent extraction of intra-lanthanides using a mixture of TBP and TODGA in ionic liquid

The recovery and separation of trivalent lanthanides into individual elements is difficult owing to their similar chemical behaviours. In this study, the solvent extraction of trivalent lanthanide ions from nitric acid solutions in an organic phase comprising a mixture of two electrically neutral extractants, viz. tri(n-butyl)phosphate (TBP) and N,N,N′,N′-tetra(n-octyl)diglycolamide (TODGA), is investigated. The hydrophobic room-temperature ionic liquid (IL), 1-methyl-3-butyl-imidazolium bis(trifluoromethanesulfonyl)imide, is employed as a more environmentally benign diluent compared to the conventional molecular solvents. The results reveal that the addition of TBP as a co-extractant with TODGA not only significantly enhances the metal ion extraction but also affords high intra-lanthanide ion selectivity. This is attributed to the formation of complex lanthanide species with both TBP and TODGA. In addition, when IL is used as a diluent, the cationic exchange between metal–organic ligand species and IL cations, as well as neutral complex extraction result in a more efficient extraction. Moreover, the hydrophobic anionic IL entities can also be involved in the extraction mechanism, affording lipophilic metal–organic ligand complexes. The synergistic solvent combination of TODGA, TBP, and IL can afford an excellent separation of the lanthanide(III) ions.

Graphene-Ionic Liquid Thin Film Nanolubricant.

Graphene (0.5 wt.%) was dispersed in the hydrophobic room-temperature ionic liquid 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide (IL) to obtain a new non-Newtonian (IL + G) nanolubricant. Thin layers of IL and (IL + G) lubricants were deposited on stainless steel disks by spin coating. The tribological performance of the new thin layers was compared with those of full fluid lubricants. Friction coefficients for neat IL were independent of lubricant film thickness. In contrast, for (IL + G) the reduction of film thickness not only afforded 40% reduction of the friction coefficient, but also prevented wear and surface damage. Results of surface profilometry, scanning and transmission electron microscopy (SEM and TEM), energy dispersive analysis (EDX), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were discussed.

A methodology to detect explosive residues using a gelled ionic liquid based field-deployable electrochemical device

A simple and robust, low-cost electrochemical device is proposed for the combined sampling and detection of the trace solid explosive 2,4,6-trinitrotoluene (TNT) from a non-porous surface. Four different substrates were investigated to collect explosive residue – a bare thin-film electrode, glass microfiber filter paper, a gel-polymer electrolyte (GPE), and a GPE-filter paper composite. The GPE contained the hydrophobic room temperature ionic liquid (RTIL) trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide ([P14,6,6,6][NTf2]) and the polymer poly(methyl methacrylate) (PMMA). A simple “swabbing” technique was used to sample explosive residue on all substrates. Square wave voltammetry was performed to determine the effects of oxygen and moisture on the current response. The most robust method for use in the field – a GPE drop-casted on a TFE – was applied in real environments using a hand-held portable potentiostat. The prototype device was able to detect TNT with a 30 min development time in different ambient environmental conditions. The portability, ease of use and low-cost of the sensor device makes this a viable platform for the rapid onsite detection of explosives.

Lithium extraction from complex aqueous solutions using supported ionic liquid membranes

This work evaluates the feasibility to separate selectively lithium cations from complex aqueous solutions containing sodium, cobalt and nickel ions using a supported liquid membranes (SLMs) impregnated with a mixture of hydrophobic ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4mim][NTf2]) and tri-n-butyl phosphate (TBP) as the carrier. Various hydrophobic room-temperature ionic liquids (ILs), namely with dialkyl imidazolium, quaternary ammonium and phosphonium cations, were tested as supporting phase in hydrophobic porous polyvinylidene fluoride (PVDF) membranes. Membrane impregnation studies show that the mass uptake is following the density of the organic phase. The stability experiments indicate that the losses of IL in the surrounding aqueous phases are related to its aqueous solubility and could be reduced by the addition of salt in the feed and/or stripping phase. Lithium membrane extraction and selective separation from aqueous complex solutions containing large amounts of sodium ions has been demonstrated. The selective separation of lithium from cobalt and nickel ions as well as from magnesium in acidic aqueous solutions has shown promising results. The results obtained in present study indicate that the use of hydrophobic IL for SLM preparation allows the facilitated transport of lithium ions.

Detection of antimuscarinic agents tolterodine and fesoterodine and their metabolite 5-hydroxymethyl tolterodine by ion transfer voltammetry at a polarized room-temperature ionic liquid membrane

Ion transfer voltammetry at a polarized hydrophobic room temperature ionic liquid (RTIL) membrane was used for evaluation of the diffusion coefficients and the standard Gibbs energies of ion transfer of the protonated antimuscarinic agents tolterodine (TOL), fesoterodine (FES), and their common metabolite 5-hydroxymethyl tolterodine (5-HMT), as well as for their determination in the aqueous samples and urine. An analysis of the pH effect provided the parameters characterizing their lipophilicity both in their ionic and neutral forms confirming a remarkably low lipophilicity of 5-HMT. The application of the ion transfer voltammetry for a monitoring of the enzymatic hydrolysis of FES to 5-HMT was demonstrated. For determination of protonated TOL, FES, and 5-HMT in the aqueous samples, linear calibration dependences were plotted in the range 2.0–12.5 μmol L−1 with the mean limit of detection (LOD) 0.43 μmol L−1. Analogous linear calibration dependences were constructed for 10times diluted urine spiked with 2.0–12.5 μmol L−1 TOL, FES, and 5-HMT with the mean LOD 0.65 μmol L−1. Unfortunately, determination of 5-HMT in diluted urine samples was interfered by an unknown ionic urine component, which somewhat increased its particular LOD.

Electrochemical Detection of Explosive Compounds in an Ionic Liquid in Mixed Environments: Influence of Oxygen, Moisture, and Other Nitroaromatics on the Sensing Response

From a security point of view, detecting and quantifying explosives in mixed environments is required to identify potentially concealed explosives. Electrochemistry offers a viable method to detect nitroaromatic explosive compounds owing to the presence of easily reducible nitro groups that give rise to a current signal. However, their reduction potentials can overlap with interfering species, making it difficult to distinguish particular compounds. We have therefore examined the effect of oxygen, moisture, and other nitroaromatic species on the cyclic voltammetry and square wave voltammetry of nitroaromatic compounds of a range of mixed environments, focussing on 2,4,6-trinitrotoluene (TNT) and 2,4-dinitrotoluene (DNT) as model analytes, and using the hydrophobic room-temperature ionic liquid (RTIL) [P14,6,6,6][NTf2] as the solvent. Oxygen (0–20% vol.) minimally affected the current of the first reduction peak of TNT in [P14,6,6,6][NTf2], but significantly affects the current for DNT. The impact of water (0 to 86% relative humidity), however, was much more dramatic – even in the hydrophobic RTIL, water significantly affected the currents of the analyte peaks for TNT and DNT, and gave rise to additional reduction features, further contributing to the current. Additionally, the voltammetry of other related di- and tri-nitro compounds (2,6-dinitrotoluene, 1,3-dinitrobenzene, 2,4,6-trinitrotoluene, 1,3,5-trinitrobenzene, and musk xylene) was also studied to understand how different substituents on the aromatic ring may affect the reduction potentials. A 50:50 mixture of TNT and DNT revealed that both analytes could be separately identified and quantified using square wave voltammetry. Overall, this information is useful in determining the effect of other species on the current signals of electrochemical explosive sensors, and reveals that it may be necessary to dry the aprotic RTIL electrolyte when used in humid environments.

Electrochemical behavior of platinum and gold electrodes in the aprotic ionic liquid N,N-Trimethylbutylammonium Bis(trifluoromethanesulfonyl)imide

The behavior of platinum and gold electrodes in the hydrophobic room-temperature ionic liquid (RTIL) N,N-Trimethylbutylammonium Bis(trifluoromethanesulfonyl)imide ([N4111][NTf2]) was investigated using transient electrochemistry e.g. voltammetry and chronoamperometry. As previously observed and contrary to what is often stated, these electrodes are not inert in the electroactivity domain of the solvent, between −3.0 and 2.7 V vs Fc/Fc+ for this RTIL. Indeed, a two-step oxidation of the platinum surface is observed at potentials higher than 1.0 V vs Fc/Fc+. The platinum oxide formed is reduced on reverse scan. Moreover, water being ubiquitous in ionic liquids, we can observe the oxidation of residual water and formation of O2. These processes both generate protons and lead to an activated state of the platinum surface. As a consequence, various signals around 0 V vs Fc/Fc+ can be attributed to the adsorption/desorption of protons and subsequent reduction to H2. In presence of water or HNTf2, this signal is enhanced. The behavior is very similar on a gold electrode but shows some specificity, particularly when it comes to the hydrogen evolution reaction.

Spent caustic treatment using hydrophobic room temperatures ionic liquids

Two hydrophobic room temperature ionic liquid (IL), tetrahexylammonium dihexyl-sulfosuccinate (IL1) and trioctylmethylammonium salicylate (IL2), have been employed for the treatment of spent caustic (SC) wastewater by liquid–liquid extraction at room temperature and pressure. The concentrations of phenols, thiols and benzaldehyde were reduced to below their detection limits and the chemical oxygen demand (COD) levels were reduced from 64166±3880mg/l to 63.0±9.0mg/l. This represents an outstanding reduction in pollutant and COD levels to well below the discharge limits for industrial effluents as set by U.S.A. Environmental Protection Agency (EPA) regulations, thus eliminating the need for any further treatment before discharge.

Hopping mode SECM imaging of redox activity in ionic liquid with glass-coated inlaid platinum nanoelectrodes prepared using a heating coil puller

Major difficulties in nanoscale scanning electrochemical microscopy (SECM), resulting from the short tip-to-sample distance, are tilt misalignment and vertical thermal drift. This renders constant height mode nanoscale electrochemical imaging experimentally problematic. Nanoscale SECM also requires application of reliable nanoprobes. Although SECM nanotips are commercially available, they are rather disposable, fragile and their shelf-life is limited. Many SECM laboratories employ self-prepared nanoprobes, fabricated using advanced apparatus. In this paper, we employ a hopping mode approach to nanoscale electrochemical imaging, which resolves the mentioned common difficulties. The applied platinum nanoelectrodes, insulated with borosilicate glass, were prepared using affordable equipment and materials. They were applied for nanoscale mapping of redox mediator regeneration at a model interdigitated microsensor, composed of Pt microband electrodes, in a solution of ferrocene in viscous hydrophobic room temperature ionic liquid (RTIL) – 1-butyl-3-methylimidazoliumbis(trifluoro-methylsulfonyl)imide (C4mim N(Tf)2). The presented nanosensors were also characterized with cyclic voltammetry in aqueous electrolyte containing hexamineruthenium (III) chloride as redox mediator.

Task-Specific Ionic Liquids as Extractants for the Solvent Extraction of Molybdenum(VI) from Aqueous Solution Using Different Commercial Ionic Liquids as Diluents

In this work, the recovery of molybdenum(VI) (Mo) from aqueous solutions was carried out by solvent extraction (SX) using ammonium and phosphonium-based task-specific ionic liquids (TSILs) as extractants diluted in kerosene and two other hydrophobic room-temperature ionic liquids (RTILs). Four different TSILs were used as extractants: trioctylmethylammonium bis(2-ethylhexyl) phosphate [TOMA][D2EHP]; trioctylmethylammonium benzoate [TOMA][BA]; trihexyltetradecylphosphonium bis(2-ethylhexyl) phosphate [P6,6,6,14][D2EHP]; and trihexyltetradecylphosphonium benzoate [P6,6,6,14][BA]. These TSILs were synthesized to assess the effect of the cation and anion on the SX of Mo(VI). Experimental results indicated that high extraction percentages of Mo(VI) were obtained with all the synthesized TSILs. Besides that, the best cation was [TOMA]+ for all the diluents and [BA]− was the best anion when kerosene and 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [omim][Tf2N], were the diluents. Furthermore, t...

Perfluoroalkyltricyanoborate and Perfluoroalkylcyanofluoroborate Anions: Building Blocks for Low-Viscosity Ionic Liquids.

The potassium perfluoroalkyltricyanoborates K[Cn F2 n+1 B(CN)3 ] [n=1 (1 d), 2 (2 d)] and the potassium mono(perfluoroalkyl)cyanofluoroborates K[Cn F2 n+1 BF(CN)2 ] [n=1 (1 c), 2 (2 c)] and [Cn F2 n+1 BF2 (CN)]- [n=1 (1 b), 2 (2 b), 3 (3 b), 4 (4 b)] are accessible with perfect selectivities on multi-gram scales starting from K[Cn F2 n+1 BF3 ] and Me3 SiCN. The K+ salts are starting materials for the preparation of salts with organic cations, for example, [EMIm]+ (EMIm=1-ethyl-3-methylimidazolium). These [EMIm]+ salts are hydrophobic room-temperature ionic liquids (RTILs) that are thermally, chemically and electrochemically very robust, offering electrochemical windows up to 5.8 V. The RTILs described herein, exhibit very low viscosities with a minimum of 14.0 mPa s at 20 °C for [EMIm]1 c, low melting points down to -57 °C for [EMIm]2 b and extraordinary high conductivities up to 17.6 mS cm-1 at 20 °C for [EMIm]1 c. The combination of these properties makes these ILs promising materials for electrochemical devices as exemplified by the application of selected RTILs as component of electrolytes in dye-sensitised solar cells (DSSCs, Grätzel cells). The efficiency of the DSSCs was found to increase with a decreasing viscosity of the neat ionic liquid. In addition to the spectroscopic characterisation, single crystals of the potassium salts of the anions 1 b-d, 2 d, 3 b and 4 c as well as of [nBu4 N]2 c have been studied by X-ray diffraction.

Fatty acid methyl ester heterogeneous self‐metathesis in hydrophobic green solvent: Mass transfer limitations, catalyst recyclability, and stability

AbstractThe role of room‐temperature ionic liquids (RTILs), [bmim][PF6] and [bmim][Tf2N], as reaction media regarding the catalytic activity and stability of methyltrioxorhenium (MTO) supported on ZnCl2‐modified mesoporous Al2O3 has been studied for self‐metathesis of a functionalized olefin, methyl oleate. The humidity influence on the catalytic activity was probed. The catalyst recycling ability and the kinetics of the metathesis reaction using these RTILs were also investigated. It was found that the MTO‐based catalyst was efficient in viscous hydrophobic RTIL solvents. However, their high viscosity was found to increase the mass transfer limitations thus somewhat impacting the reaction kinetics. Nevertheless, better catalyst stability was reached allowing its possible recycling when used in RTIL media.

Thermophysical and Electrochemical Properties of Ethereal Functionalised Cyclic Alkylammonium-based Ionic Liquids as Potential Electrolytes for Electrochemical Applications.

A series of hydrophobic room temperature ionic liquids (ILs) based on ethereal functionalised pyrrolidinium, piperidinium and azepanium cations bearing the bis[(trifluoromethyl)sulfonyl]imide, [TFSI]−, anion were synthesized and characterized. Their physicochemical properties such as density, viscosity and electrolytic conductivity, and thermal properties including phase transition behaviour and decomposition temperature have been measured. All of the ILs showed low melting point, low viscosity and good conductivity and the latter properties have been discussed in terms of the IL fragility, an important electrolyte feature of the transport properties of glass‐forming ILs. Furthermore, the studied [TFSI]−‐based ILs generally exhibit good electrochemical stabilities and, by coupling electrochemical experiments and DFT calculations, the effect of ether functionalisation at the IL cation on the electrochemical stability of the IL is discussed. Preliminary investigations into the Li‐redox chemistry at a Cu working electrode are also reported as a function of ether‐functionality within the pyrrolidinium‐based IL family. Overall, the results show that these ionic liquids are suitable for electrochemical devices such as battery systems, fuel cells or supercapacitors.

Detection of 2,4,6-Trinitrotoluene Using a Miniaturized, Disposable Electrochemical Sensor with an Ionic Liquid Gel-Polymer Electrolyte Film.

A new electrochemical method to detect and quantify the explosive compound 2,4,6-trinitrotoluene (TNT) in aqueous solutions is demonstrated. A disposable thin-film electrode modified with a droplet of a gel-polymer electrolyte (GPE) was immersed directly into samples of TNT at concentrations of 1-10 μg/mL. The GPE contained the hydrophobic room-temperature ionic liquid (RTIL) trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide ([P14,6,6,6][NTf2]) and the polymer poly(hexyl methacrylate). The RTIL acted to preconcentrate TNT into the GPE and provided ionic conductivity. The polymer provided both (i) sufficient viscosity to ensure mechanical stability of the GPE and (ii) strong hydrophobicity to minimize leaching of the RTIL. Square wave voltammetry was performed on the first reduction peak of TNT-preconcentrated samples (15 min soaking with mechanical stirring), with linear plots of peak current vs cumulative concentration of TNT, giving an averaged limit of detection of 0.37 μg/mL (aqueous phase concentration). Additionally, the voltammetry of the first reduction peak of TNT in [P14,6,6,6][NTf2] was unaffected by the presence of oxygen-in contrast to that observed in an imidazolium-based RTIL-providing excellent selectivity over oxygen in real environments. The sensor device was able to quickly and easily quantify TNT concentrations at typical ground water contamination levels. The low-cost and portability of the sensor device, along with the minimal amounts of GPE materials required, make this a viable platform for the onsite monitoring of explosives, which is currently a significant operational challenge.