TNT Concentrations Research Articles

Efficient removal of 2,4,6-trinitrotoluene (TNT) from industrial/military wastewater using anodic oxidation on boron-doped diamond electrodes

With growing public concern about water quality particular focus should be placed on organic micropollutants, which are harmful to the environment and people. Hence, the objective of this research is to enhance the security and resilience of water resources by developing an efficient system for reclaiming industrial/military wastewater and protecting recipients from the toxic and cancerogenic explosive compound—2,4,6-trinitrotoluene (TNT), which has been widely distributed in the environment. This research used an anodic oxidation (AO) process on a boron-doped diamond (BDD) electrode for the TNT removal from artificial and real-life matrices: marine water and treated wastewater. During experiments, TNT concentrations were significantly decreased, reaching the anodic degradation efficiency of above 92% within two hours and > 99.9% after six hours of environmental sample treatment. The presented results show the great potential of AO performed on BDD anodes for full-scale application in the industry and military sectors for TNT removal.

Movement of TNT and RDX from composition B detonation residues in solution and sediment during runoff

Energetics used in military exercises can potentially contaminate ground and surface waters. This study was conducted to evaluate the movement of Composition B, a formulation that includes TNT (2,4,6-trinitrotoluene), RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), and HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), in runoff. Mechanisms of transport we examined include movement of energetics dissolved in runoff, as particles and adsorbed to suspended sediment, and in infiltration. Rainfall simulations were conducted under controlled conditions with two rainfall rates (approximately 30 and 50 mm h−1), two soils with different infiltration capacities, and four energetic particle sizes (4.75–9.51 mm, 2.83–4.75 mm, 2–2.83 mm, and <2 mm). Particles remaining on the soil surface after rainfall were measured as well as energetics dissolved in runoff, in suspended sediment, and in infiltration. Greater concentrations of TNT than RDX and HMX were found dissolved in runoff due to its higher solubility and dissolution rates. We also found that particle transport in runoff increased with decrease in particle size. Smaller particle sizes also led to greater transport dissolved in solution. Relationships were found relating runoff and sediment yield to the transport of RDX and TNT. The results of this study allow improved prediction of Composition B transport in runoff and therefore its contamination potential.

Investigating the Potential of Fusarium solani and Phanerochaete chrysosporium in the Removal of 2,4,6-TNT.

Past and recent applications of 2,4,6-trinitrotoluene (TNT) in military and civilian industries have led to contamination of soil and marine ecosystems. Among various TNT remediation techniques, biological remediation is widely accepted for its sustainability, low cost, and scalable applications. This study was designed to isolate a fungus strain from a TNT-contaminated soil to investigate its tolerance to and potential for removal of TNT. Thus, a soil column with a history of periodic TNT amendment was used to isolate dominant strains of fungi Fusarium solani isolate, which is not commonly reported for TNT mineralization and was found predominant in the subsurface layer of the TNT-amended soil. F. solani was investigated for TNT concentration tolerance at 30, 70, and 100mg/L on agar plates and for TNT removal in liquid cultures at the same given concentrations. F. solani activity was compared with that of a reference soil-born fungus that has been intensively studied for TNT removal (Phanerochaete chrysosporium) obtained from the American Type Culture Collection. On agar media, F. solani showed a larger colony diameter than P. chrysosporium at similar TNT concentrations, indicating its high potential to tolerate toxic levels of TNT as found in contaminated sites. In the liquid culture medium, F. solani was able to significantly produce higher biomass than P. chrysosporium in all TNT concentrations. The TNT removal percentage from the liquid culture at the highest TNT concentration of 100mg/L reached about 85% with F. solani, while P. chrysosporium was no better than 25% at the end of an 84-h incubation period. Results indicate a significant potential of using F. solani in the bioremediation of polluted TNT soils that overcome the high concentration barrier in the field. However, further investigation is needed to identify enzymatic potential and the most effective applications and possible limitations of this method on a large scale.

Evaluation of a sequential anaerobic-aerobic membrane bioreactor system for treatment of traditional and insensitive munitions constituents

New energetic formulations containing insensitive high explosives (IHE), such as 2,4-dinitroanisole (DNAN), 3-nitro-1,2,4-triazole-5-one (NTO), and nitroguanidine (NQ) are being developed to provide safer munitions. The addition of IHE to munitions formulations results in complex wastewaters from explosives manufacturing, load and pour operations and demilitarization activities. New technologies are required to treat those wastewaters. The core objective of this research effort was to develop and optimize a dual anaerobic-aerobic membrane bioreactor (MBR) system for treatment of wastewater containing variable mixtures of traditional energetics, IHE, and anions. The combined system proved highly effective for treatment of traditional explosives (TNT, RDX, HMX), IHE (DNAN, NTO, NQ) and anions commonly used as military oxidants (ClO4−, NO3−). The anaerobic MBR, which was operated for more than 500 d, was observed to completely degrade mg L−1 concentrations of TNT, DNAN, ClO4− and NO3− under all operational conditions, including at the lowest hydraulic residence time (HRT) tested (2.2 d). The combined system generally resulted in complete treatment of mg L−1 concentrations of RDX and HMX to <20 μg L−1, with most of the degradation occurring in the anaerobic MBR and polishing in the aerobic system. No common daughter products of DNAN, TNT, RDX, or HMX were detected in the effluent. NTO was completely transformed in the anaerobic MBR, but residual 3-amino-1,2,4-triazole-5-one (ATO) was detected in system effluent. The ATO rapidly decomposed when bleach solution was added to the final effluent. NQ was initially recalcitrant in the system, but microbial populations eventually developed that could degrade >90% of the ∼10 mg L−1 NQ entering the anaerobic MBR, with the remainder degraded to <50 μg L−1 in the aerobic system. The dual MBR system proved to be capable of complete degradation of a wide mixture of munitions constituents and was resilient to changing influent composition.

Groth’s algorithm to detect the possible presence of landmines using changes in the reflection of plants

Abstract. Post-conflict reconstruction includes the removal of land mines and remnants of war. The CSIR conducted field experiments to determine the impact of TNT in the soil on plants as a possible means to detect landmines. All the leaf clip readings were done using a spectrometer to determine reflection and absorption of light at one micrometre intervals between 350 to 2500 micrometre. Laboratory analysis such as UPLC qTOF MS indicated that the TNT have an influence on the plants. Several indices such as Modified Red Edge Normalized Difference Vegetation Index (mNDVI705), Red Edge Position (REP) and Moisture Stress Index (MSI) did not show any significant differences between control plants and experimental plants with different TNT concentrations. Groth’s pattern matching algorithm designed to match several photographs of the same part of the universe. A set of triangles using dominant stars are created for each photograph and matched using an error band. If the selected triangles from the two photographs fit within the error band, then they are from the same section of the universe. Bands for the Pléiades instruments were simulated using the data from the spectrometer for each plant. The reflectance value of the band and the normalised midpoint wavelength of each Pléiades band were used to construct the triangles. The control plant triangle is then matched with the experimental plant and if the triangles do not match, then the effect of TNT on the plant is significant. The initial results with the control plants and experimental plants are positive.

A novel coupling-activated GO nanocomposites based on surface acoustic wave for assessing capture molecules and detection of explosive gases

Surface acoustic wave (SAW) technology has been widely used in the field of hazardous gas detection, but there are still many problems to be solved such as long response/recovery time, poor selectivity and repeatability. In this study, we evaluated the adsorption capacity of various explosive capture molecules using SAW devices and designed a sensing material for 2,4,6-trinitrotoluene (TNT) gas detection by coupling 4-aminothiophenol (PATP), which has the best adsorption capacity, to activated graphene oxide (GO) via a disulfide exchange scheme. The SAW sensor based on graphene oxide/2-(2-Pyridyldisulfide) ethylamine hydrochloride/4-aminothiophenol (GO/PDEA/PATP) has a theoretical detection limit (DL) as low as 2.8 ppb, short response/recovery time (15/45 s < ), good repeatability, stability selectivity and interference immunity. The enhanced mechanism for its high sensitivity and selectivity detection for TNT is based on the formation of a "Meisenheimer" complex by multiple strong interactions between PATP and TNT. Of course, the formation of this complex also leads to incomplete recovery of the sensor in high TNT concentrations. The scientific findings of this work will provide new idea for exploring the next generation of acoustic gas-phase explosives sensors.

Inhibition effect of 2,4,6-trinitrotoluene (TNT) on RDX degradation by rhodococcus strains isolated from contaminated soil and water

2,4,6-trinitrotoluene (TNT) is a highly toxic explosive that contaminates soil and water and may interfere with the degradation of co-occurring compounds, such as hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). We proposed that TNT may influence RDX-degrading bacteria via either general toxicity or a specific effect on the |RDX degradation mechanisms. Thus, we examined the impact of TNT on RDX degradation by Rhodococcus strains YH1, T7, and YY1, which were isolated from an explosives-polluted environment. Although partly degraded, TNT did not support the growth of any of the strains when used as either sole carbon or sole nitrogen sources, or as carbon and nitrogen sources. The incubation of a mixture of TNT (25 mg/l) and RDX (20 mg/l) completely inhibited RDX degradation. The effect of TNT on the cytochrome P450, catalyzing RDX degradation, was tested in a resting cell experiment, proving that TNT inhibits XplA protein activity. A dose-response experiment showed that the IC50/trans values for YH1, T7, and YY1 were 7.272, 5.098, and 9.140 (mg/l of TNT), respectively, illustrating variable sensitivity to TNT among the strains. The expression of xplA was also strongly suppressed by TNT. Cells that were pre-grown with RDX (allowing xplA expression) and incubated with ammonium chloride, glucose, and TNT, completely transformed into their amino dinitrotoluene isomers and formed azoxy toluene isomers. The presence of oxygen-insensitive nitroreductase that enable reduction of the nitro group in the presence of O2 in the genomes of these strains suggests that they are responsible for TNT transformation in the cultures. The experimental results concluded that TNT has an adverse effect on RDX degradation by the examined strains. It inhibits RDX degradation due to the direct impact on cytochrome P450, xplA, or its expression. The tested strains can transform TNT independently of RDX. Thus, degradation of both compounds is possible if TNT concentrations are below their IC50 values.

C53 DONOR–DERIVED CELL–FREE DNA (DD–CFDNA)–BASED ASSESSMENT OF CORONARY ALLOGRAFT VASCULOPATHY IN HEART TRANSPLANTED PATIENTS

Abstract Introduction Cardiac Allograft Vasculopathy (CAV) is a leading cause of long–term graft dysfunction and failure after Heart Transplant (HTx). Early diagnosis is crucial to tailor therapeutic strategies. Despite advancements in cardiac imaging, the standard for CAV diagnosis remains coronary angiography. Donor–derived cell free DNA (dd–cfDNA) is a novel marker of graft injury in solid organ transplants. Elevations in dd–cfDNA levels may reflect CAV development during subclinical inflammation, thus it could represent a non–invasive method of surveillance for CAV rejection in apparently stable post–transplant patients. Given these premises, we decided to evaluate the potential of dd–cfDNA as alternative diagnostic biomarker for CAV. Materials and Methods 31 blood samples from patients who underwent heart transplant at our institution in the last 10 years, were analyzed by Next Generation Sequencing (NGS) according to CareDx Alloseq protocol. The cfDNA was extracted starting from 2mL of plasma (Qiagen). Sequencing was performed on the Illumina Miseq platform. Troponin T (hs–TnT) and NT–proBNP (Brain Natriuretic Peptide) were measured by automated immunoassay analysers. All statistics were performed by STATA software and significance was set at p &amp;lt; 0.05. Results Heart transplant recipients were divided into 2 groups: 16 patients with known CAV status and 15 patients who had not (no–CAV). No significant differences between the two populations were observed, aside from time from HTx (177.28± 84.99 months in CAV vs 93.20 ± 84.39 months in no–CAV; p = 0.033). A significant difference in dd–cfDNA fraction was found between CAV and no–CAV patients (p = 0.03); with mean values of 0,41% e 0,13%, respectively. Neither NT-proBNP (p = 0.08) nor hs–TnT (p = 0.31) concentrations were significantly different between the two groups, but a positive correlation was found between the two biomarkers (r 0.6966; p = 0.0013). A trend of linear relationship emerged between cfDNA and NT-proBNP levels (r 0.4155; p = 0.08). Conclusions With this study, we demonstrated the feasibility of evaluating dd–cfDNA in long–term heart transplanted patients and its possible association with CAV development. Further investigations are warranted to explore a possible association between dd–cfDNA levels other circulating biomarkers and CAV progression. The definition of “homogeneous” subgroups of patients according to a “risk score” will allow to better manage their follow up and improve their prognosis.

A novel strategy for high-throughput sample collection, analysis and visualization of explosives’ concentrations for contaminated areas

The use of explosives has led to a widespread distribution of 2,4,6-trinitrotoluene (TNT) and its by- and degradation products in the soil on former production and testing sites. The investigation of those large contaminated sites is so far based on a few selected soil samples, due to high costs of conventional HPLC and GC analysis, although huge differences in concentrations can already be found in small areas and different collection depths. We introduce a novel high-throughput screening system for those areas, which combines a smartphone-based collection of GPS data and soil characteristics with a fast MALDI-TOF MS quantification of explosives in soil sample extracts and finally a heatmap visualization of the explosives’ spread in soil and an analysis of correlation between concentrations and soil characteristics. The analysis of a 400 m2 area presented an extensive contamination with TNT and lower concentrations of the degradation and by-products aminodinitrotoluenes (ADNT) and dinitrotoluenes (DNT) next to a former production facility for TNT. The contamination decreased in deeper soil levels and depended on the soil type. Pure humus samples showed significantly lower contaminations compared to sand and humus/sand mixtures, which is likely to be caused by an increased binding potential of the humic material. No correlation was found between the vegetation and the concentration of explosives. Since the results were obtained and visualized within several hours, the MALDI-TOF MS based comprehensive screening and heatmap analysis might be valuable for a fast and high-throughput characterization of contaminated areas.

MoS2 QDs/8-Armed Poly(Ethylene Glycol) Fluorescence Sensor for Three Nitrotoluenes (TNT) Detection.

In this work, ammonia cross-linked 8-armed polyethylene glycol hydrogel material was successfully synthesized and used as a template for synthesizing nanoparticles with fluorescent properties. The 8-armed polyethylene glycol hydrogel template was used to prepare molybdenum disulfide quantum dots (MoS2 QDs). The ammonium tetrathiomolybdate functioned as a molybdenum source and hydrazine hydrate functioned as a reducing agent. The fluorescence properties of the as-prepared MoS2 QDs were investigated. The bursting of fluorescence caused by adding different concentrations of explosive TNT was studied. The study indicated that the synthesized MoS2 QDs can be used for trace TNT detection with a detection limit of 6 nmol/L and a detection range of 16–700 nmol/L. Furthermore, it indicated that the fluorescence-bursting mechanism is static bursting.

P-Oligophenylene-based polymeric fluorescent nanofilms. Synthesis, electrooptical characterization and application in aqueous phase nitroaromatic detection

Model compounds and new polymeric materials bearing p -terphenylene and p -quaterphenylene units tethered by their para-positions were synthesized. PTF , with terphenylene groups tethered with C(CF 3 ) 2 groups, reached the higher polymerization degrees. All these materials, except PTF , show variable amounts of local ordering in the form of J- and H-aggregates. The insensibility of the fluorescence response of PTF films to casting conditions or the excitation wavelength makes it a good candidate for thin-film chemosensory applications. Thus, thin films of PTF and its biphenylene homolog PBF were used as fluorescent active layers for sensitive detection of nitroaromatics in water media. PTF films are quite sensitive to nanomolar concentrations of TNT, the quenching being a combination of PET and IFE contributions. PBF presents a weaker response to TNT that arises from hindered TNT diffusion into the polymeric film. On the contrary, PBF is very sensitive towards picric acid, PA. The sensing configuration polymeric film/aqueous solution studied here demonstrated promising potential for the direct sensing of nitroaromatics in water bodies of industrial and city areas. • Synthesis of terphenylene and quaterphenylene macromolecular materials. • PTF , with p -terphenylene tethered by C(CF3)2 groups, was soluble and amorphous. • All materials, except PTF , present local ordering as H- and J-aggregates. • Fluorescence response of PTF films is independent of casting conditions or λexc • The fluorescence of PTF and PBF films is responsive to nanomolar solutions of TNT and PA.

Voltammetric Detection of Explosives in Wet Environments with Ionic Liquids and Ionogels

2,4,6-Trinitrotoluene (TNT) is an explosive compound commonly used for industrial, military, as well as mining applications. It is also used by terrorists in homemade explosives, due to its insensitivity to shock and friction compared to other high explosives such as nitroglycerin. At mining sites where TNT is used for land clearing, if not completely removed after detonation, TNT and its reduction products may contaminate ground water and rivers — which is an environmental issue since they are known to be toxic and carcinogenic to humans. The development of sensors for explosives such as TNT is therefore of huge interest due to the wide range of security and environmental concerns. In recent years, room temperature ionic liquids (RTILs) have been investigated as a replacement solvent in sensors1 due to their favourable properties including wide electrochemical windows, intrinsic conductivity, high chemical and physical stability, and the ability to dissolve a wide range of analytes. However, RTILs are liquid and tend to flow, which makes the sensor not sufficiently robust for portable applications due to electrolyte spillage. To overcome this, we have mixed a RTIL with a cheap and widely available methacrylate polymer to produce a non-flowing ionogel, which we refer to as a gel polymer electrolyte (GPE).2 It was observed that the electrochemical signal in the GPE was significantly less affected in humid environments compared to the neat RTIL, where water molecules can act as proton donors, altering the mechanism of electrochemical reactions leading to sensor instability.2 Notably, the voltammetry of TNT in a hydrophobic RTIL was found to be unaffected by the presence of oxygen, which allows for selectivity over oxygen and moisture for the detection of TNT in real environments.4 With the choice of a hydrophobic RTIL/polymer mixture and the use of a cheap commercially available thin-film electrode, we have developed a new electrochemical system that enables direct detection and quantification of TNT in aqueous solutions (see Figure 1).3 The RTIL acts to preconcentrate TNT into the GPE and provides ionic conductivity, while the hydrophobic polymer serves to increase viscosity to ensure mechanical stability of the GPE while immersed in water, in addition to blocking water from reaching the electrode surface. Using square wave voltammetry, linear plots of peak current vs. concentration of TNT were obtained, and the sensor device was able to quickly and easily quantify TNT concentrations at typical ground water contamination levels via. liquid/liquid extraction mechanism. The low-cost and portability of the sensor device, along with the minimal amounts of GPE materials required, makes this a viable platform for the onsite monitoring of explosives, which is currently a significant operational challenge. Our GPEs may further allow for rapid and easy forensic surveying and detection of explosives in real-environments with simple and portable equipment — which we are presently developing; negating the need for the samples to be transferred to a lab to be analysed with expensive bulky instruments, and the need for careful pre-processing of the samples. The ability to immediately detect explosives onsite also reduces the chances of residue decomposition and possible contamination of samples during transport.Our polymer/RTIL based materials can readily be extended to the sensing of other redox active explosive materials, and other analyte species as well. The ease of mass production and low cost of our electrode/GPE system, along with the minimal amounts of RTIL and polymer required for the GPE, make this a viable electrochemical sensing device to be applied on a bulk scale, in a wide range of environmental conditions.

In vitro pulmonary toxicity of thermally processed titania nanotubes

The current study examined the in vitro pulmonary toxicity of titania nanotubes induced by the morphological and crystalline changes associated with post-synthetic thermal processing. A549 lung carcinoma cells were exposed to untreated, amorphous titania nanotubes and those treated at 200, 400, 600 and 800 °C, respectively. The cytotoxic action of the untreated and annealed TNTs was assessed using a battery of cytotoxicity assays that examined cellular metabolic and prolific activity and membrane integrity, in addition to the production of intracellular reactive oxygen species (ROS). Toxicity effects due to the period and dose of exposure were determined by exposing the A549 cell line to various TNT concentrations during different incubation periods. The untreated, amorphous and annealed TNTs elicited an overall dose-dependent increase in toxicity. As the annealing temperature increased from 200 to 800 °C, the nanotubular structure of TNTs fragmented and a crystalline phase composition developed. Crystalline nanoparticles also began to grow among the walls of disintegrated TNTs, and crystallite and particle size increased progressively. In comparison to amorphous TNTs, those of anatase, rutile or anatase/rutile mixed-phase composition exerted notable in vitro pulmonary toxicity. Rutile-rich TNTs possessing fragmented nanotube walls and larger particle size induced the greatest loss in viability of A549 lung carcinoma cells, presumably due to the domination of the rigid rutile crystal arrangement. The current study thus highlights the necessity for material manufacturers to consider the effects of post-synthetic processing on the possible toxicity profile of nanomaterial containing products and devices.

Effect of Remote Ischemic Preconditioning on Outcomes in Adult Cardiac Surgery: A Systematic Review and Meta-analysis of Randomized Controlled Studies.

Remote ischemic preconditioning (RIPC) has been demonstrated to prevent organ dysfunction in cardiac surgery patients. However, recent large, prospective, multicenter, randomized controlled trials (RCTs) had controversial results. Thus, a meta-analysis of RCTs was performed to investigate whether RIPC can reduce the incidence of acute myocardial infarction (AMI), acute kidney injury (AKI), and mortality in adult cardiac surgery patients. Study data were collected from Medline, Elsevier, Cochrane Central Register of Controlled Trials and Web of Science databases. RCTs involving the effect of RIPC on organ protection in cardiac surgery patients, which reported the concentration or total release of creatine kinase-myocardial band, troponin I/troponin T (TNI/TNT) after operation, or the incidence of AMI, AKI, or mortality, were selected. Two reviewers independently extracted data using a standardized data extraction protocol where TNI or TNT concentrations; total TNI released after cardiac surgery; and the incidence of AKI, AMI, and mortality were recorded. Review Manager 5.3 software was used to analyze the data. Thirty trials, including 7036 patients were included in the analyses. RIPC significantly decreased the concentration of TNI/TNT (standard mean difference [SMD], -0.25 ng/mL; 95% confidence interval [CI], -0.41 to -0.048 ng/mL; P = .004), creatine kinase-myocardial band (SMD, -0.22; 95% CI, -0.07-0.35 ng/mL; P = .46), and the total TNI/TNT release (SMD, -0.49 ng/mL; 95% CI, -0.93 to -0.55 ng/mL; P = .03) in cardiac surgery patients after a procedure. However, RIPC could not reduce the incidence of AMI (relative risk, 0.89; 95% CI, 0.70-1.13; P = .34) and AKI (relative risk, 0.88; 95% CI, 0.72-1.06; P = .18), and there was also no effect of RIPC on mortality in adult cardiac surgery patients. Interestingly, subgroup analysis showed that RIPC reduced incidence of AKI and mortality of cardiac surgery patients who received volatile agent anesthesia. Our meta-analysis demonstrated that RIPC reduced TNI/TNT release after cardiac surgery. RIPC did not significantly reduce the incidence of AKI, AMI, and mortality. However, RIPC could reduce mortality in patients receiving volatile inhalational agent anesthesia.

Enhanced Aerobic Biodegradation of Soil Contaminated with Explosives (TNT and PETN) By Rhamnolipid

The aim of this study was to investigate the bioremediation of two explosives 2, 4, 6-trinitrotoluene (TNT) and Pentaerythritol Tetranitrate (PETN) in mixture by aerobic process. Microbial inocula were obtained from a textile wastewater treatment plant activated sludge. Addition of rhamnolipid surfactant (60 mg/l) increased the removal efficiencies of TNT and PETN from 53% and 57% to 98% and 91%, respectively. Explosives degradation reaction is expressed to be of first-order and the kinetic reaction parameters are calculated based on different initial concentrations of TNT and PETN. The first-order rate constants of the rhamnolipid amended experiments were at least 3 orders and 2.5 orders of magnitude higher for TNT and PETN, respectively, than those found for not amended rhamnolipid experiments. The metabolites pentaerythritoldinitrate, 3-hydroxy-2,2-bis [(nitrooxy) methyl] propanal, and2,2-bis-[(nitrooxy) methyl]-propanedialfor PETN and2-amino-4, 6dinitrotoluene and 4-amino-2, 6-dinitrotoluene for TNT were identified by LC-MS. Concomitant degradation of TNT and PETN resulted in decrease of environment pH. Inoculated bacteria have capability to use of explosive as source of nitrogen and energy. It seems that the addition of rhamnolipid showed great potential for treatment of explosives by textile activated sludge. Keywords Author Keywords:TNT; PETN; rhamnolipid; textile activated sludge KeyWords Plus:PENTAERYTHRITOL TETRANITRATE PETN; DEGRADATION; 2,4,6-TRINITROTOLUENE; BIOREMEDIATION; BIOSURFACTANTS; MINERALIZATION

Proteomic profiling of vetiver grass (Chrysopogon zizanioides) under 2,4,6-trinitrotoluene (TNT) stress.

Vetiver grass is an ideal plant for 2,4,6‐trinitrotoluene (TNT) phytoremediation, due to its ability to tolerate and metabolize TNT as previously reported. The current study is the first attempt to investigate the changes in the proteomic profile of a plant under TNT stress. Vetiver plants were grown in nutrient media with varying concentrations of TNT (0, 25, 50, and 100 mg L−1) for 10 days. Although the plants appeared healthy, significant biomass reductions (p = 0.0008) were observed in treated plants. Total proteins in the root decreased significantly (p = 0.0003). Proteomic analysis of root proteins revealed the downregulation of functional proteins involved in key cellular mechanisms such as transcription, ribosome biogenesis, nucleo‐cytoplasmic transport of proteins, protein glycosylation, and translation. Growth‐related proteins were downregulated; plant defense proteins were upregulated at lower TNT concentrations but downregulated at higher concentrations. Comprehensive understanding of changes in the proteomic profile provides important clues to the mechanism of TNT stress response and tolerance in vetiver.

Kinetics of nitroreductase-mediated phytotransformation of TNT in vetiver grass

The effectiveness of vetiver grass in removing 2,4,6-trinitrotoluene (TNT) and the involvement of nitroreductase (NR) enzyme in TNT degradation in vetiver has been documented in our earlier studies. The present study was designed to optimize the parameters influencing NR enzyme-mediated TNT transformation in vetiver. The current study is the first report of detailed kinetic examination of NR enzyme induced by TNT in vetiver. Results show that NR activity in vetiver root increased with exposure time as well as with initial TNT concentration, showing a first-order reaction kinetics at lower and a second-order reaction kinetics at higher TNT concentrations. Nitroreductase activity was higher in shoot compared to root in all TNT treatments. Increasing concentration of TNT resulted in a significant increase in the NR activity in shoot. Very high increase in the shoot NR activity indicates a faster root-to-shoot translocation of TNT. The optimum range of the factors influencing NR-mediated TNT transformation and the kinetic parameters were determined, which will be crucial for the application of vetiver for phytoremediation of TNT-contaminated systems.

Highly sensitive gas-phase explosive detection by luminescent microporous polymer networks.

We propose microporous networks (MPNs) of a light emitting spiro-carbazole based polymer (PSpCz) as luminescent sensor for nitro-aromatic compounds. The MPNs used in this study can be easily synthesized on arbitrarily sized/shaped substrates by simple and low-cost electrochemical deposition. The resulting MPN afford an extremely high specific surface area of 1300 m2/g, more than three orders of magnitude higher than that of the thin films of the respective monomer. We demonstrate, that the luminescence of PSpCz is selectively quenched by nitro-aromatic analytes, e.g. nitrobenzene, 2,4-DNT and TNT. In striking contrast to a control sample based on non-porous spiro-carbazole, which does not show any luminescence quenching upon exposure to TNT at levels of 3 ppm and below, the microporous PSpCz shows a clearly detectable response even at TNT concentrations as low as 5 ppb, clearly demonstrating the advantage of microporous films as luminescent sensors for traces of explosive analytes. This level states the vapor pressure of TNT at room temperature.

Colorimetric-based detection of TNT explosives using functionalized silica nanoparticles.

This proof-of-concept study proposes a novel sensing mechanism for selective and label-free detection of 2,4,6-trinitrotoluene (TNT). It is realized by surface chemistry functionalization of silica nanoparticles (NPs) with 3-aminopropyl-triethoxysilane (APTES). The primary amine anchored to the surface of the silica nanoparticles (SiO2-NH2) acts as a capturing probe for TNT target binding to form Meisenheimer amine–TNT complexes. A colorimetric change of the self-assembled (SAM) NP samples from the initial green of a SiO2-NH2 nanoparticle film towards red was observed after successful attachment of TNT, which was confirmed as a result of the increased separation between the nanoparticles. The shift in the peak wavelength of the reflected light normal to the film surface (λpeak) and the associated change of the peak width were measured, and a merit function taking into account their combined effect was proposed for the detection of TNT concentrations from 10−12 to 10−4 molar. The selectivity of our sensing approach is confirmed by using TNT-bound nanoparticles incubated in AptamerX, with 2,4-dinitrotoluene (DNT) and toluene used as control and baseline, respectively. Our results show the repeatable systematic color change with the TNT concentration and the possibility to develop a robust, easy-to-use, and low-cost TNT detection method for performing a sensitive, reliable, and semi-quantitative detection in a wide detection range.

Degradation of 2,4,6-trinitrotoluene by P. aeruginosa and characterization of some metabolites.

Degradation of 2,4,6-trinitrotoluene (TNT), a nitroaromatic explosive found in the soil and ground water, was investigated using Pseudomonas aeruginosa in in vitro experiments . Biodegradable abilitiy of this bacteria was performed with 50 and 75 mg L −1 TNT concentrations in a defined liquid medium for 96 h time period. Treatment of TNT in supernatant samples taken at 0, 6, 12, 24, 48, 72 and 96 h from agitated vessels was followed by reverse-phase high-performance liquid chromatography (HPLC). In cultures supplemented with 50 and 75 mgL −1 TNT, after 96 h of incubation 46% and 59% reduction were detected respectively. Two metabolites as degradation intermediates with nitrite release into the medium, 2,4-dinitrotoluene (2,4-DNT) and 4-aminodinitrotoluene (4-ADNT), were elucidated by thin layer chromatography (TLC) and gas chromatography-mass spectrometry (GC-MS). These findings clearly indicate that Pseudomonas aeruginosa can be used in bioremediation of TNT contaminated sites.