• Microbiology and Biotechnology Letters
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• v.32 no.3
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• pp.230-237
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• 2004

In this study nitroreductase from Pseudomonas sp. HK-6 capable of degrading 2,4,6-trinitrotoluene (TNT) was characterized. Through a series of purification process including ammonium sulfate precipitation, DEAE-sepharose, and Q-sepharose, three different fractions I, II, and III having the enzyme activity of NTRs whose molecular weights were approximately 27 kDa were detected in fractions from HK-6 cells. Specific activity of the three fractions were approximately 4.85 unit/mg, 5.47 unit/mg, and 5.01 unit/mg, and concentrated to 9.0-, 10.1-, and 9.3-fold compared to crude extract, respectively. The optimal pH and temperature for the three NTR fractions were approximately 7.5 and $30^{\circ}C$, respectively. Metal ions, $Ag^{＋}$ , $Cu^{ 2+}$, $Hg^{2＋}$ inhibited approximately 70% of enzymes activities of all NTR, while $Fe^{2＋}$ did not stimulate or inhibit the activities. Monitoring the effect of chemicals on the enzyme activity revealed that those NTR fractions lost enzyme activity in presence of $\beta$-mercaptoethanol, but were a little influenced by dithiothreitol, EDTA and NaCl. The three NTR fractions demonstrated enzyme activities for nitrobenzene and RDX as well as TNT.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.235-238
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• 2002

Microorganisms were isolated from military shooting site. Aerobic batch reactor and resting cell condition experiments were carried out using isolated microorganisms. Experiments were examined at room temperature on shaker and ten-roll mixer. During 10 days of reaction time, TNT was degraded 15.51 ~ 22.47 mg/L from initial concentration(31$\pm$1 mg/L) by aerobic batch reactor. Aerobic resting cell condition experiments were carried out ill phosphate buffer with 58($\pm$1) mg/L TNT at pH of 6.0($\pm$0.2). TNT was degraded 67.8% of initial concentration. The mai or component was found 4-ADNT(4-Aminodinitrotoluene).

• Proceedings of the Korean Environmental Health Society Conference
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• 2004.06a
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• pp.160-164
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• 2004

This study was carried out to investigate the removal of TNT (2,4,6-trinitrotoluene) and parathion in the batch and the continuous constructed wetland microcosms consisting of marsh and pond. The batch system study showed that TNT was almost reduced in the marsh and pond system within 20 days and parathion was within 8 days. The major reductive metabolites of TNT includes 2,4-diamino-6-nitrotoluene (24DANT) >2,6-diamino-4-nitrotoluene (26DANT) >4-diamino-2,6-nitrotoluene(4ADNT) > 2-diamino-4,6-nitrotoluene (2ADNT), and the concentrations of these metabolites were decreased during further operation. The generation rates of 4-nitrophenol, the major metabolite of parathion, were 82% and 15% in the bottom of marsh and pond system, respectively. In the continuous system study, although TNT/parathion degradation pattern was similar to the batch's, marsh-pond system showed the most stable TNT/ parathion removal among various continuous reactor combinations.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.2
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• pp.282-288
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• 2014

In this research, we investigated synthetic method of 2,6-DANT that can be used as a chain extender of urethane/urea and epoxy materials in a demilitarization method via chemical transformations considering environmental, economical aspects and stability of process. We was able to identify through GC monitoring that 2,4-DANT and 2,6-DANT were produced when we inject 'hydrazine monohydrate 3.3 eq. by TNT 1 eq.' with a fine metering pump for 30 minutes and then, reflux for an additional 2 hours. We was able to isolate only 2,6-DANT(99.3% purity and 45.0% yield) from mixture of 2,4-DANT and 2,6-DANT through the separating and refining methods using 2,6-DANT solubility in methanol and crystallinity of 2,6-DANT.

• Advances in environmental research
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• v.1 no.1
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• pp.1-14
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• 2012

We demonstrated that reductive degradation of 2,4,6-Trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (Royal Demolition Explosive, RDX) can be enhanced by bio-reduced iron-bearing soil minerals (IBSMs) using Shewanella putrefaciens CN32 (CN32). The degradation kinetic rate constant of TNT by bio-reduced magnetite was the highest (0.0039 $h^{-1}$), followed by green rust (0.0022 $h^{-1}$), goethite (0.0017 $h^{-1}$), lepidocrocite (0.0016 $h^{-1}$), and hematite (0.0006 $h^{-1}$). The highest rate constant was obtained by bio-reduced lepidocrocite (0.1811 $h^{-1}$) during RDX degradation, followed by magnetite (0.1700 $h^{-1}$), green rust (0.0757 $h^{-1}$), hematite (0.0495 $h^{-1}$), and goethite (0.0394 $h^{-1}$). Significant increase of Fe(II) was observed during the reductive degradation of TNT and RDX by bio-reduced IBSMs. X-ray diffraction and electron microscope analyses were conducted for identification of degradation mechanism of TNT and RDX in this study. 4-amino-dinitrotoluene were detected as products during TNT degradation, while Hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine, Hexahydro-1,3-dinitroso-5-nitro-1,3,5triazine, and Hexahydro-1,3,5-trinitroso-1,3,5-triazine were observed during RDX degradation.

• KSBB Journal
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• v.24 no.6
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• pp.556-562
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• 2009

The biological treatment of TNT-containing wastewater, known commonly as pink water, was investigated using a stirred tank reactor with Stenotrophomonas maltophilia OK-5 bacterial culture. S. maltophilia OK-5 exhibited effective degradation of TNT contained in pink water, completely degrading TNT (100 mg/L) within 6 days of incubation. The dark-red brown color derived from Hydride-Meisenheimer complex became more pronounced during the incubation period, which was determined quantitatively. High-pressure liquid chromatography was used to measure residual TNT, which also resolved the metabolic intermediates (i.e., 2,4-dinitrotoluene, 2,6-dinitrotoluene and 2,4-dinitro-6-hydroxytoluene). Gas chromatography-mass spectrometry was used to verify these intermediates. Quantification of the nitroreductase (pnrB) gene isolated from S. maltophilia OK-5 growing in pink water was performed with real-time PCR. The amount of pnrB gene copies increased to $10^3$-fold after 5 days of incubation time.

• Journal of Soil and Groundwater Environment
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• v.11 no.6
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• pp.76-82
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• 2006

Fenton's reaction are difficult to apply in the field due to the low pH requirements for the reaction and the loss of reactivity caused by the precipitation of iron (II) at neutral pH. Moreover, Fenton-like reactions using iron mineral instead of injection of iron ion as a catalyst are operated to get high removal result at low pH. Because hydroxyl radical can generate at the surface of iron mineral, there are competition with a lot of hydroxide at around neutral pH. On the other side, to operate Fenton's reaction series at neutral pH, modified Fenton reaction is suggested. The complexes, composed by iron ions (ferrous ion or ferric ion)-chelating agent, could be acted as a catalyst and presented in the solution at neutral pH. However, modified Fenton reaction requires a lot of hydrogen peroxide. Accordingly, the purpose of this experiment was to effectively combine Fenton-like reaction and modified Fenton reaction for extending application of Fenton's reaction. i.e., injecting chelating agents in Fenton-like reaction at around neutral pH is increasing the concentration of dissolved iron ion and highly promoting the oxidation effect. 2,4,6-trinitrotoluene (TNT) was used as a probe compound for comparing reaction efficiencies in this study. If the concentration of dissolved iron ion in combined Fenton process were existed more than 0.1 mM, the total TNT removal were increased. Magnetite-NTA system showed the best TNT removal (76%) and Magnetite-EDTA system indicated about 56% of TNT removal. The results of these experiments proved more promoted 40-60% of TNT removal than Fenton-like reaction's.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.1
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• pp.127-143
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• 2016

Over the decades, TNT has been produced indiscriminately to be utilized in many fields owing to its ability to manipulate the explosion. Yet, the proper technique for disposal of TNT and the waste residues had not been developed so that the large amount of TNT waste was being piled up. Upon the agreement to demilitarization of old weapon, a study on the disposal methods for TNT and the waste treatment have been raised for their dangerous nature. Since then, from burying in landfill to utilizing supercritical fluid-based oxidation, a lot of research is actively ongoing, but little progress has been made in Korea compared to developed countries. This review paper covers all the technologies developed for TNT and its waste disposal including the concept, advantage, and disadvantage of those technologies. Also, suggested here are the future research directions.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.43-46
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• 2004

Explosive chemicals have been major soil and groundwater contaminants especially in the nations with active military activities. Of these explosives, 2,4,6-trinitrotoluene (TNT) is the most refractory one due to its structural characteristics. Although its efficient reduction by Fe(0) is well-known, the reduction products - mainly aminotoluenes - still possess toxicities to terrestrial biota, and are resistant to biological degradation. In this study, therefore, abiotic transformation of TNT reduction products via oxidative-coupling reaction was evaluated using Mn oxide which is ubiquitous in natural soils. The transformation efficiency is increased with the number of amino groups. Considering the very efficient reduction rate of TNT by Fe(0), Mn oxide can be successfully used for the removal of TNT reduction products.

• Korean Chemical Engineering Research
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• v.45 no.3
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• pp.298-303
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• 2007

Several combinations of ozone based advanced oxidation processes were tested for the treatment of red water (RW) containing recalcitrant chemical pollutants produced from 2,4,6-trinitrotoluene (TNT) manufacturing process. $O_3$, $UV/O_3$, $UV/O_3/H_2O_2$, $UV/O_3/H_2O_2/Fe^{2+}$ processes were tested for the treatment of RW. The order of organic and color removal efficiency was found to be : $O_3{\leq}UV/O_3$ < $UV/O_3/H_2O_2$ < $UV/O_3/H_2O_2/Fe^{2+}$. The optimum conditions for the removal of organic and color in the $UV/O_3/H_2O_2/Fe^{2+}$ process were 0.053 g/min of ozone flow rate, 10 mM of $H_2O_2$ concentration and 0.1 mM of $FeSO_4$ concentration. Organic and color removal efficiencies were 96 and 100 % respectively in the $UV/O_3/H_2O_2/Fe^{2+}$ process. tert-butyl alcohol (t-buOH) was used as the hydroxyl radical scavenger. Enhancement of hydroxyl radical production was achieved by the combination of ozone with several oxidants such as UV, $H_2O_2$, $Fe^{2+}$.