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Michael K Stenstrom - One of the best experts on this subject based on the ideXlab platform.
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fenton oxidation of hexahydro 1 3 5 trinitro 1 3 5 triazine RDX and octahydro 1 3 5 7 tetranitro 1 3 5 7 tetrazocine hmx
Water Research, 2002Co-Authors: Kyungduk Zoh, Michael K StenstromAbstract:Abstract Oxidation of the high explosives hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) using Fenton's reagent proceeds rapidly between 20°C and 50°C at pH 3. At an H 2 O 2 : Fe 2+ : RDX molar ratio of 5178 : 48 : 1, RDX and HMX were completely removed in 1 to 2 h. All the experimental data could be fit to a pseudo first-order rate equation. The reaction rate was also strongly dependent on Fenton’s reagent concentrations. NO 3 − and N 2 were identified as nitrogen byproducts from RDX and HMX oxidation. The experiment with radiolabeled RDX showed that approximately 37% of organic carbon in RDX was mineralized to CO 2 . We observed formaldehyde and formic acid as a short-lived intermediate. No other volatile or nonvolatile byproducts were found from GC/MS analysis. The results show that RDX and HMX can be effectively mineralized with Fenton's reagents.
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kinetics of the alkaline hydrolysis of high explosives RDX and hmx in aqueous solution and adsorbed to activated carbon
Environmental Science & Technology, 1996Co-Authors: Harro M Heilmann, And Udo Wiesmann, Michael K StenstromAbstract:Aqueous alkaline hydrolysis of bulk quantities and wastewater contaminated with high explosives is a promising technology for treatment and disposal of the worldwide surplus of munitions. We investigated the hydrolysis kinetics of the high explosives hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) for temperatures ranging from 50 to 80 °C and in the pH range from 10 to 12. The experimental data were described using a pseudo-first-order model with subsequent calculation of second-order rate constants from experiments with excess hydroxide concentration. The temperature dependency of the rate constants was evaluated using the Arrhenius model. The activation energies were determined to be ERDX = 99.9 ± 1.9 kJ mol-1 and EHMX = 111.9 ± 0.8 kJ mol-1. The rate of HMX hydrolysis is much slower than the rate of RDX hydrolysis and may become rate limiting in the treatment of RDX/HMX mixtures. The alkaline hydrolysis of RDX yields 1.6 M NO2-, 1.5 M HCOO-, 0.1 ...
Jalal Hawari - One of the best experts on this subject based on the ideXlab platform.
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role of soil interstitial water in the accumulation of hexahydro 1 3 5 trinitro 1 3 5 triazine in the earthworm eisenia andrei
Environmental Toxicology and Chemistry, 2010Co-Authors: Kathleen Savard, Manon Sarrazin, Sabine Dodard, Roman G Kuperman, Jalal Hawari, Fanny Monteilrivera, Geoffrey I SunaharaAbstract:The uptake of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) from soil by the earthworm Eisenia andrei was examined by using the equilibrium partitioning (EqP) theory and a three-compartment model including soil (S), interstitial water (IW), and earthworms (E). The RDX concentrations were measured using U.S. Environmental Protection Agency (U.S. EPA) Method 8330A and high-performance liquid chromatography (HPLC). The S-IW studies were conducted using four natural soils with contrasting physicochemical properties that were hypothesized to affect the bioavailability of RDX. Each soil was amended with nominal RDX concentrations ranging from 1 to 10,000 mg/kg. The HPLC analysis showed that the IW extracted from soil was saturated with RDX at 80 mg/kg or greater soil concentrations. The calculated S-IW coefficient (Kp) values for RDX ranged from 0.4 to 1.8 ml/g soil, depending on the soil type, and were influenced by the organic matter content. In the IW-E studies, earthworms were exposed to nonlethal RDX concentrations in aqueous media. The uptake of RDX by the earthworms correlated well (r2 = 0.99) with the dissolved RDX concentrations. For the E-S studies, earthworms were exposed to RDX-amended soils used in the S-IW studies. The bioconcentration factors (BCF; ratios of E-to-IW RDX concentrations) were relatively constant (∼5) up to 80 mg/kg soil RDX concentrations, which encompass the RDX saturation limit in the interstitial water of the tested soils. At this concentration range, the RDX uptake from interstitial water was likely dominated by passive diffusion and could be used as an indicator of bioavailability. Other mechanisms may be involved at greater RDX soil concentrations. Environ. Toxicol. Chem. 2010;29:998–1005. © 2009 SETAC
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accumulation of hexahydro 1 3 5 trinitro 1 3 5 triazine by the earthworm eisenia andrei in a sandy loam soil
Environmental Toxicology and Chemistry, 2009Co-Authors: Manon Sarrazin, Sabine Dodard, Kathleen Savard, Bernard Lachance, Pierre Yves Robidoux, Roman G Kuperman, Jalal Hawari, Guy Ampleman, Sonia Thiboutot, Geoffrey I SunaharaAbstract:The heterocyclic polynitramine hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a highly energetic compound found as a soil contaminant at some defense installations. Although RDX is not lethal to soil invertebrates at concentrations up to 10,000 mg/kg, it decreases earthworm cocoon formation and juvenile production at environmentally relevant concentrations found at contaminated sites. Very little is known about the uptake of RDX in earthworms and the potential risks for food-chain transfer of RDX in the environment. Toxicokinetic studies were conducted to quantify the bioaccumulation factors (BAFs) using adult earthworms (Eisenia andrei) exposed for up to 14 d to sublethal concentrations of nonlabeled RDX or [14C]RDX in a Sassafras sandy loam soil. High-performance liquid chromatography of acetonitrile extracts of tissue and soil samples indicated that nonlabeled RDX can be accumulated by the earthworm in a concentration- and time-dependent manner. The BAF, expressed as the earthworm tissue to soil concentration ratio, decreased from 6.7 to 0.1 when the nominal soil RDX concentrations were increased from 1 to 10,000 mg/kg. Tissue concentrations were comparable in earthworms exposed to nonlabeled RDX or [14C]RDX. The RDX bioaccumulation also was estimated using the kinetically derived model (BAFK), based on the ratio of the uptake to elimination rate constants. The established BAFK of 3.6 for [14C]RDX uptake was consistent with the results for nonlabeled RDX. Radioactivity also was present in the tissue residues of [14C]RDX-exposed earthworms following acetonitrile extraction, suggesting the formation of nonextractable [14C]RDX metabolites associated with tissue macromolecules. These findings demonstrated a net accumulation of RDX in the earthworm and the potential for food-chain transfer of RDX to higher-trophic-level receptors.
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biodegradation of the nitramine explosives hexahydro 1 3 5 trinitro 1 3 5 triazine and octahydro 1 3 5 7 tetranitro 1 3 5 7 tetrazocine in cold marine sediment under anaerobic and oligotrophic conditions
Canadian Journal of Microbiology, 2004Co-Authors: Jianshen Zhao, Sonia Thiboutot, Guy Ampleman, Charles W Greer, Jalal HawariAbstract:The in situ degradation of the two nitramine explosives, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), was evaluated using a mixture of RDX and HMX, incubated anaerobically at 10 °C with marine sediment from a previous military dumping site of unexploded ordnance (UXO) in Halifax Harbor, Nova Scotia, Canada. The RDX concentration (14.7 mg·L–1) in the aqueous phase was reduced by half in 4 days, while reduction of HMX concentration (1.2 mg·L–1) by half required 50 days. Supplementation with the carbon sources glucose, acetate, or citrate did not affect the removal rate of RDX but improved removal of HMX. Optimal mineralization of RDX and HMX was obtained in the presence of glucose. Using universally labeled (UL)-[14C]RDX, we obtained a carbon mass balance distributed as follows: CO2, 48%–58%; water soluble products, 27%–31%; acetonitrile extractable products, 2.0%–3.4%; and products covalently bound to the sediments and biomass, 8.9% (in the prese...
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photodegradation of RDX in aqueous solution a mechanistic probe for biodegradation with rhodococcus sp
Environmental Science & Technology, 2002Co-Authors: Jalal Hawari, Annamaria Halasz, Louise Paquet, Chantale Beaulieu, Carl A Groom, Stephane Deschamps, A CorriveauAbstract:Recently we demonstrated that Rhodococcus sp. strain DN22 degraded hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) (I) aerobically via initial denitration followed by ring cleavage. Using UL 14C-[RDX] and ring labeled 15N-[RDX] approximately 30% of the energetic chemical mineralized (one C atom) and 64% converted to a dead end product that was tentatively identified as 4-nitro-2,4-diaza-butanal (OHCHNCH2NHNO2). To have further insight into the role of initial denitration on RDX decomposition, we photolyzed the energetic chemical at 350 nm and pH 5.5 and monitored the reaction using a combination of analytical techniques. GC/MS-PCI showed a product with a [M + H] at 176 Da matching a molecular formula of C3H5N5O4 that was tentatively identified as the initially denitrated RDX product pentahydro-3,5-dinitro-1,3,5-triazacyclohex-1-ene (II). LC/MS (ES-) showed that the removal of RDX was accompanied by the formation of two other key products, each showing the same [M − H] at 192 Da matching a molecular formula ...
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insights into the formation and degradation mechanisms of methylenedinitramine during the incubation of RDX with anaerobic sludge
Environmental Science & Technology, 2002Co-Authors: Annamaria Halasz, Louise Paquet, Jim C Spain, Chantale Beaulieu, Jalal HawariAbstract:In an earlier study, we reported that hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) biodegraded with domestic anaerobic sludge to produce a key RDX ring cleavage intermediate that was tentatively identified as methylenedinitramine (O2NNHCH2NHNO2) using LC/MS with negative electrospray ionization (ES-). Recently, we obtained a standard material of methylenedinitramine and thus were able to confirm its formation as the key initial RDX intermediate. In water alone or in the presence of sludge, methylenedinitramine decomposed to N20 and HCHO. Only in the presence of sludge HCHO converted further to carbon dioxide. To test our hypothesis that water was involved in the formation of methylenedinitramine during incubation of RDX with sludge, we allowed the energetic compound to biodegrade in several D2O/H2O solutions (90, 50, and 0% v/v). We observed three distinctive deprotonated or dedeuterated mass ions at 135, 136, and 137 Da that were attributed to the formation of nondeuterated (H-methylenedinitramine), monodeuterated (D1-methylenedinitramine), and dideuterated methylenedinitramine (D2-methylenedinitramine), respectively. Two controls were prepared in D2O both in the absence of sludge; the first contained methylenedinitramine, and the second contained RDX. Neither control produced any deuterated methylenedinitramine, thus excluding the occurrence of any abiotic D/H exchange between D2O and either methylenedinitramine or RDX. The results supported the occurrence of an initial enzymatic reaction on RDX, yet they did not provide compelling evidence on whether methylenedinitramine was an initial RDX enzymatic hydrolysis product or simply formed via the spontaneous hydrolysis of an anonymous initial RDX enzymatic product.
Geoffrey I Sunahara - One of the best experts on this subject based on the ideXlab platform.
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role of soil interstitial water in the accumulation of hexahydro 1 3 5 trinitro 1 3 5 triazine in the earthworm eisenia andrei
Environmental Toxicology and Chemistry, 2010Co-Authors: Kathleen Savard, Manon Sarrazin, Sabine Dodard, Roman G Kuperman, Jalal Hawari, Fanny Monteilrivera, Geoffrey I SunaharaAbstract:The uptake of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) from soil by the earthworm Eisenia andrei was examined by using the equilibrium partitioning (EqP) theory and a three-compartment model including soil (S), interstitial water (IW), and earthworms (E). The RDX concentrations were measured using U.S. Environmental Protection Agency (U.S. EPA) Method 8330A and high-performance liquid chromatography (HPLC). The S-IW studies were conducted using four natural soils with contrasting physicochemical properties that were hypothesized to affect the bioavailability of RDX. Each soil was amended with nominal RDX concentrations ranging from 1 to 10,000 mg/kg. The HPLC analysis showed that the IW extracted from soil was saturated with RDX at 80 mg/kg or greater soil concentrations. The calculated S-IW coefficient (Kp) values for RDX ranged from 0.4 to 1.8 ml/g soil, depending on the soil type, and were influenced by the organic matter content. In the IW-E studies, earthworms were exposed to nonlethal RDX concentrations in aqueous media. The uptake of RDX by the earthworms correlated well (r2 = 0.99) with the dissolved RDX concentrations. For the E-S studies, earthworms were exposed to RDX-amended soils used in the S-IW studies. The bioconcentration factors (BCF; ratios of E-to-IW RDX concentrations) were relatively constant (∼5) up to 80 mg/kg soil RDX concentrations, which encompass the RDX saturation limit in the interstitial water of the tested soils. At this concentration range, the RDX uptake from interstitial water was likely dominated by passive diffusion and could be used as an indicator of bioavailability. Other mechanisms may be involved at greater RDX soil concentrations. Environ. Toxicol. Chem. 2010;29:998–1005. © 2009 SETAC
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accumulation of hexahydro 1 3 5 trinitro 1 3 5 triazine by the earthworm eisenia andrei in a sandy loam soil
Environmental Toxicology and Chemistry, 2009Co-Authors: Manon Sarrazin, Sabine Dodard, Kathleen Savard, Bernard Lachance, Pierre Yves Robidoux, Roman G Kuperman, Jalal Hawari, Guy Ampleman, Sonia Thiboutot, Geoffrey I SunaharaAbstract:The heterocyclic polynitramine hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a highly energetic compound found as a soil contaminant at some defense installations. Although RDX is not lethal to soil invertebrates at concentrations up to 10,000 mg/kg, it decreases earthworm cocoon formation and juvenile production at environmentally relevant concentrations found at contaminated sites. Very little is known about the uptake of RDX in earthworms and the potential risks for food-chain transfer of RDX in the environment. Toxicokinetic studies were conducted to quantify the bioaccumulation factors (BAFs) using adult earthworms (Eisenia andrei) exposed for up to 14 d to sublethal concentrations of nonlabeled RDX or [14C]RDX in a Sassafras sandy loam soil. High-performance liquid chromatography of acetonitrile extracts of tissue and soil samples indicated that nonlabeled RDX can be accumulated by the earthworm in a concentration- and time-dependent manner. The BAF, expressed as the earthworm tissue to soil concentration ratio, decreased from 6.7 to 0.1 when the nominal soil RDX concentrations were increased from 1 to 10,000 mg/kg. Tissue concentrations were comparable in earthworms exposed to nonlabeled RDX or [14C]RDX. The RDX bioaccumulation also was estimated using the kinetically derived model (BAFK), based on the ratio of the uptake to elimination rate constants. The established BAFK of 3.6 for [14C]RDX uptake was consistent with the results for nonlabeled RDX. Radioactivity also was present in the tissue residues of [14C]RDX-exposed earthworms following acetonitrile extraction, suggesting the formation of nonextractable [14C]RDX metabolites associated with tissue macromolecules. These findings demonstrated a net accumulation of RDX in the earthworm and the potential for food-chain transfer of RDX to higher-trophic-level receptors.
Kyungduk Zoh - One of the best experts on this subject based on the ideXlab platform.
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fenton oxidation of hexahydro 1 3 5 trinitro 1 3 5 triazine RDX and octahydro 1 3 5 7 tetranitro 1 3 5 7 tetrazocine hmx
Water Research, 2002Co-Authors: Kyungduk Zoh, Michael K StenstromAbstract:Abstract Oxidation of the high explosives hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) using Fenton's reagent proceeds rapidly between 20°C and 50°C at pH 3. At an H 2 O 2 : Fe 2+ : RDX molar ratio of 5178 : 48 : 1, RDX and HMX were completely removed in 1 to 2 h. All the experimental data could be fit to a pseudo first-order rate equation. The reaction rate was also strongly dependent on Fenton’s reagent concentrations. NO 3 − and N 2 were identified as nitrogen byproducts from RDX and HMX oxidation. The experiment with radiolabeled RDX showed that approximately 37% of organic carbon in RDX was mineralized to CO 2 . We observed formaldehyde and formic acid as a short-lived intermediate. No other volatile or nonvolatile byproducts were found from GC/MS analysis. The results show that RDX and HMX can be effectively mineralized with Fenton's reagents.
Pat J Unkefer - One of the best experts on this subject based on the ideXlab platform.
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isolation of three hexahydro 1 3 5 trinitro 1 3 5 triazine degrading species of the family enterobacteriaceae from nitramine explosive contaminated soil
Applied and Environmental Microbiology, 1994Co-Authors: Christopher Kitts, Daryl P Cunningham, Pat J UnkeferAbstract:Three species of the family Enterobacteriaceae that biochemically reduced hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) were isolated from nitramine explosive-contaminated soil. Two isolates, identified as Morganella morganii and Providencia rettgeri, completely transformed both RDX and the nitroso-RDX reduction intermediates. The third isolate, identified as Citrobacter freundii, partially transformed RDX and generated high concentrations of nitroso-RDX intermediates. All three isolates produced 14CO2 from labeled RDX under O2-depleted culture conditions. While all three isolates transformed HMX, only M. morganii transformed HMX in the presence of RDX.
