scholarly journals Photo-transformation of aqueous nitroguanidine and 3-nitro-1,2,4-triazol-5-one : emerging munitions compounds

2021 ◽  
Author(s):  
Julie Becher ◽  
Samuel Beal ◽  
Susan Taylor ◽  
Katerina Dontsova ◽  
Dean Wilcox
Keyword(s):  
Aqueous Solutions ◽  
Degradation Products ◽  
Pure Water ◽  
Transformation Products ◽  
Water Soluble ◽  
Uv Exposure ◽  
Degradation Pathways ◽  
Solution Ph ◽  
Photo Degradation ◽  
Degradation Rates

Two major components of insensitive munition formulations, nitroguanidine (NQ) and 3-nitro-1,2,4-triazol-5-one (NTO), are highly water soluble and therefore likely to photo-transform while in solution in the environment. The ecotoxicities of NQ and NTO solutions are known to increase with UV exposure, but a detailed accounting of aqueous degradation rates, products, and pathways under different exposure wavelengths is currently lacking. We irradiated aqueous solutions of NQ and NTO over a 32-h period at three ultraviolet wavelengths and analyzed their degradation rates and transformation products. NQ was completely degraded by 30 min at 254 nm and by 4 h at 300 nm, but it was only 10% degraded after 32 h at 350 nm. Mass recoveries of NQ and its transformation products were >80% for all three wavelengths. NTO degradation was greatest at 300 nm with 3% remaining after 32 h, followed by 254 nm (7% remaining) and 350 nm (20% remaining). Mass recoveries of NTO and its transformation products were high for the first 8 h but decreased to 22–48% by 32 h. Environmental half-lives of NQ and NTO in pure water were estimated as 4 and 6 days, respectively. We propose photo-degradation pathways for NQ and NTO supported by observed and quantified degradation products and changes in solution pH.

scholarly journals Solar photodegradation of carbamazepine from aqueous solutions using a compound parabolic concentrator equipped with a sun tracking system

2019 ◽  
Vol 17 (1) ◽  
pp. 477-484 ◽  
Author(s):  
Ahmadreza Yazdanbakhsh ◽  
Reza Nemati ◽  
Mohamadreza Massoudinejad ◽  
Mohamadjavad Jafari ◽  
Masoomeh Dashtdar
Keyword(s):  
Organic Compound ◽  
Aqueous Solutions ◽  
Tracking System ◽  
Transformation Rate ◽  
Solution Ph ◽  
Photo Degradation ◽  
Compound Parabolic Concentrator ◽  
Reactor Temperature ◽  
By Products ◽  
Complete Mineralization

AbstractThe primary purpose of this study was to investigate the efficiency of a Compound Parabolic Concentrator (CPC) equipped with a sun tracking system in the photolysis of carbamazepine as a refractory organic compound. The natural sunlight experiments were accomplished during the period May–July 2017 in Tehran, Iran. The intermediate by-products of the process of solar photodegradation of carbamazepine (CBZ) were characterized using LC–MS. The results showed that increasing the reactor temperature did not significantly change CBZ degradation efficiency. However, the solution pH played a comparatively important role in CBZ solar photo degradation: removal efficiency increased considerably with pH from about 49% at pH 7 to almost 61% at pH 9. According to our findings, using a CPC reactor equipped with a sun tracker system promotes the solar photo-transformation rate of CBZ by 2-3 fold. In addition, LC/MS analysis showed that eight main intermediates were formed in the treated solution after solar photodegradation of CBZ. Therefore, complete mineralization of CBZ was not accomplished.

Hydrolysis of polydimethylsiloxane fluids in controlled aqueous solutions

2013 ◽  
Vol 68 (4) ◽  
pp. 813-820 ◽  
Author(s):  
Gaëlle Ducom ◽  
Baptiste Laubie ◽  
Aurélie Ohannessian ◽  
Claire Chottier ◽  
Patrick Germain ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Wastewater Treatment Plants ◽  
Degradation Products ◽  
Kinetic Studies ◽  
Solution Ph ◽  
Degradation Kinetic ◽  
Silicon Compounds ◽  
Alkaline Conditions ◽  
Naoh Solution ◽  
Water Ph

Accelerated degradation tests were performed on polydimethylsiloxane (PDMS) fluids in aqueous solutions and in extreme chemical conditions (pH 2–4 and 9–12). Results confirmed that silicones can be degraded by hydrolysis. Higher degradation levels were achieved in very acidic and alkaline conditions. Degradation products are probably polar siloxanols. In alkaline conditions, the counter-ion was found to have a strong influence on degradation level. Degradation kinetic studies (46 days) were also performed at different pH values. Supposing zeroth-order kinetics, degradation rate constants at 24 °C were estimated to 0.28 mgSi L−1 day−1 in NaOH solution (pH 12), 0.07 mgSi L−1 day−1 in HCl solution (pH 2) and 0.002 mgSi L−1 day−1 in demineralised water (pH 6). From these results, the following hypothesis was drawn: PDMS hydrolysis could occur in wastewater treatment plants and in landfill cells. It may be a first step in the formation of volatile organic silicon compounds (VOSiCs, including siloxanes) in biogas: coupled to biodegradation and (self-) condensation of degradation products, it could finally lead to VOSiCs.

scholarly journals Comparison of Advanced Oxidation Processes for the Degradation of Maprotiline in Water—Kinetics, Degradation Products and Potential Ecotoxicity

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 240
Author(s):  
Nuno P. F Gonçalves ◽  
Zsuzsanna Varga ◽  
Edith Nicol ◽  
Paola Calza ◽  
Stéphane Bouchonnet
Keyword(s):  
Ring Opening ◽  
Advanced Oxidation Processes ◽  
High Resolution Mass Spectrometry ◽  
Degradation Products ◽  
Reproductive Toxicity ◽  
Transformation Products ◽  
Degradation Pathways ◽  
Aromatic Rings ◽  
Oxidation Processes ◽  
The Impact

The impact of different oxidation processes on the maprotiline degradation pathways was investigated by liquid chromatography-high resolution mass spectrometry (LC/HRMS) experiments. The in-house SPIX software was used to process HRMS data allowing to ensure the potential singular species formed. Semiconductors photocatalysts, namely Fe-ZnO, Ce-ZnO and TiO2, proved to be more efficient than heterogeneous photo-Fenton processes in the presence of hydrogen peroxide and persulfate. No significant differences were observed in the degradation pathways in the presence of photocatalysis, while the SO4− mediated process promote the formation of different transformation products (TPs). Species resulting from ring-openings were observed with higher persistence in the presence of SO4−. In-silico tests on mutagenicity, developmental/reproductive toxicity, Fathead minnow LC50, D. magna LC50, fish acute LC50 were carried out to estimate the toxicity of the identified transformation products. Low toxicant properties were estimated for TPs resulting from hydroxylation onto bridge rather than onto aromatic rings, as well as those resulting from the ring-opening.

Anion effects in the formation of the active catalyst in the Ruhrchemie – Rhône-Poulenc aqueous biphasic hydroformylation process. Are there any?

2005 ◽  
Vol 83 (6-7) ◽  
pp. 1033-1036 ◽  
Author(s):  
József Kovács ◽  
Ferenc Joó ◽  
Carl D Frohning
Keyword(s):  
Aqueous Solutions ◽  
Active Catalyst ◽  
Water Soluble ◽  
Catalyst Precursor ◽  
Solution Ph ◽  
Aqueous Biphasic ◽  
First Time ◽  
Close Analogue

The water soluble [Rh(OAc)(CO)(mtppms)2] containing monosulfonated triphenylphosphine ligands was prepared for the first time and its hydrogenation was studied in aqueous solutions. In the presence of additional mtppms, the reaction yielded [RhH(CO)(mtppms)3], a close analogue of [RhH(CO)(mtppts)3], the immediate catalyst precursor in the Ruhrchemie – Rhône-Poulenc aqueous biphasic hydroformylation process. The extent of the [Rh(OAc)(CO)(mtppms)2] → [RhH(CO)(mtppms)3] transformation strongly depended on the solution pH, similar to the case of the hydrogenation of [RhCl(CO)(mtppms)2] studied earlier. In this respect, RhCl3·aq and Rh(OAc)3·aq can be used equally well for the in situ preformation of [RhH(CO)(mtppts)3], although the latter is the preferred choice in the industrial process.Key words: rhodium, water-soluble, hydrides, sulfonated phosphines, biphasic.

scholarly journals Further Understanding of Degradation Pathways of Microcystin-LR by an Indigenous Sphingopyxis sp. in Environmentally Relevant Pollution Concentrations

Toxins ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 536 ◽  
Author(s):  
Qin Ding ◽  
Kaiyan Liu ◽  
Kai Xu ◽  
Rongli Sun ◽  
Juan Zhang ◽  
...  
Keyword(s):  
Microbial Degradation ◽  
Degradation Products ◽  
Lake Taihu ◽  
Environmental Safety ◽  
Degradation Pathways ◽  
Environment Friendly ◽  
Degradation Rates ◽  
Degrading Bacteria ◽  
Full Scan ◽  
Pollution Concentrations

Microcystin-LR (MC-LR) is the most widely distributed microcystin (MC) that is hazardous to environmental safety and public health, due to high toxicity. Microbial degradation is regarded as an effective and environment-friendly method to remove it, however, the performance of MC-degrading bacteria in environmentally relevant pollution concentrations of MC-LR and the degradation pathways remain unclear. In this study, one autochthonous bacterium, Sphingopyxis sp. m6 which exhibited high MC-LR degradation ability, was isolated from Lake Taihu, and the degrading characteristics in environmentally relevant pollution concentrations were demonstrated. In addition, degradation products were identified by utilizing the full scan mode of UPLC-MS/MS. The data illustrated that strain m6 could decompose MC-LR (1–50 μg/L) completely within 4 h. The degradation rates were significantly affected by temperatures, pH and MC-LR concentrations. Moreover, except for the typical degradation products of MC-LR (linearized MC-LR, tetrapeptide, and Adda), there were 8 different products identified, namely, three tripeptides (Adda-Glu-Mdha, Glu-Mdha-Ala, and Leu-MeAsp-Arg), three dipeptides (Glu-Mdha, Mdha-Ala, and MeAsp-Arg) and two amino acids (Leu, and Arg). To our knowledge, this is the first report of Mdha-Ala, MeAsp-Arg, and Leu as MC-LR metabolites. This study expanded microbial degradation pathways of MC-LR, which lays a foundation for exploring degradation mechanisms and eliminating the pollution of microcystins (MCs).

Sorbitol enhances the physicochemical stability of B12 vitamers

2020 ◽  
Vol 90 (5-6) ◽  
pp. 439-447 ◽  
Author(s):  
Andrew Hadinata Lie ◽  
Maria V Chandra-Hioe ◽  
Jayashree Arcot
Keyword(s):  
Ascorbic Acid ◽  
Uv Light ◽  
Heat Exposure ◽  
Water Soluble ◽  
Uv Exposure ◽  
Physicochemical Stability ◽  
Before And After ◽  
The Stability

Abstract. The stability of B12 vitamers is affected by interaction with other water-soluble vitamins, UV light, heat, and pH. This study compared the degradation losses in cyanocobalamin, hydroxocobalamin and methylcobalamin due to the physicochemical exposure before and after the addition of sorbitol. The degradation losses of cyanocobalamin in the presence of increasing concentrations of thiamin and niacin ranged between 6%-13% and added sorbitol significantly prevented the loss of cyanocobalamin (p<0.05). Hydroxocobalamin and methylcobalamin exhibited degradation losses ranging from 24%–26% and 48%–76%, respectively; added sorbitol significantly minimised the loss to 10% and 20%, respectively (p < 0.05). Methylcobalamin was the most susceptible to degradation when co-existing with ascorbic acid, followed by hydroxocobalamin and cyanocobalamin. The presence of ascorbic acid caused the greatest degradation loss in methylcobalamin (70%-76%), which was minimised to 16% with added sorbitol (p < 0.05). Heat exposure (100 °C, 60 minutes) caused a greater loss of cyanocobalamin (38%) than UV exposure (4%). However, degradation losses in hydroxocobalamin and methylcobalamin due to UV and heat exposures were comparable (>30%). At pH 3, methylcobalamin was the most unstable showing 79% degradation loss, which was down to 12% after sorbitol was added (p < 0.05). The losses of cyanocobalamin at pH 3 and pH 9 (~15%) were prevented by adding sorbitol. Addition of sorbitol to hydroxocobalamin at pH 3 and pH 9 reduced the loss by only 6%. The results showed that cyanocobalamin was the most stable, followed by hydroxocobalamin and methylcobalamin. Added sorbitol was sufficient to significantly enhance the stability of cobalamins against degradative agents and conditions.

Photo-degradation of monoazo dye blue 13 using advanced oxidation process

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Aqueous Solution ◽  
Advanced Oxidation Process ◽  
Oxidation Process ◽  
High Energy ◽  
Uv Exposure ◽  
H2o2 Concentration ◽  
Oxidizing Agent ◽  
Photo Degradation ◽  
High Energy Radiation ◽  
Uv Lamp

The high energy radiation overcome the bonding of solute in a solution and H2O2 acts as an oxidizing agent and generates a free radical in the solution which results in photo-degradation by converting the solute in to simple form and resultantly, colored substance under the effect of photo-degradation becomes colorless. The photo-degradation of monoazo dye Blue 13 in an aqueous solution was investigated using a laboratory scale UV lamp in the presence of H2O2 and for maximum degradation of dye, the independent parameter UV power, UV exposure time, pH and H2O2 concentration were optimized. It was found that neither UV in the presence of H2O2 is able to degrade Blue 13 under optimum condition. The results revealed that the use of both UV and H2O2 have pronounced effect on the discoloration of dyes which could be used for management of textile effluents contain waste dyes.

scholarly journals Degradation Products of Polychlorinated Biphenyls and Their In Vitro Transformation by Ligninolytic Fungi

Toxics ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 81
Author(s):  
Kamila Šrédlová ◽  
Kateřina Šírová ◽  
Tatiana Stella ◽  
Tomáš Cajthaml
Keyword(s):  
Polychlorinated Biphenyls ◽  
Extracellular Enzymes ◽  
Degradation Products ◽  
Transformation Products ◽  
Irpex Lacteus ◽  
Chlorobenzoic Acid ◽  
Ligninolytic Fungi ◽  
Wide Range ◽  
Pcb Metabolites

Metabolites of polychlorinated biphenyls (PCBs)—hydroxylated PCBs (OH‑PCBs), chlorobenzyl alcohols (CB‑OHs), and chlorobenzaldehydes (CB‑CHOs)—were incubated in vitro with the extracellular liquid of Pleurotus ostreatus, which contains mainly laccase and low manganese-dependent peroxidase (MnP) activity. The enzymes were able to decrease the amount of most of the tested OH‑PCBs by > 80% within 1 h; the removal of more recalcitrant OH‑PCBs was greatly enhanced by the addition of the laccase mediator syringaldehyde. Conversely, glutathione substantially hindered the reaction, suggesting that it acted as a laccase inhibitor. Hydroxylated dibenzofuran and chlorobenzoic acid were identified as transformation products of OH‑PCBs. The extracellular enzymes also oxidized the CB‑OHs to the corresponding CB‑CHOs on the order of hours to days; however, the mediated and nonmediated setups exhibited only slight differences, and the participating enzymes could not be determined. When CB‑CHOs were used as the substrates, only partial transformation was observed. In an additional experiment, the extracellular liquid of Irpex lacteus, which contains predominantly MnP, was able to efficiently transform CB‑CHOs with the aid of glutathione; mono‑ and di-chloroacetophenones were detected as transformation products. These results demonstrate that extracellular enzymes of ligninolytic fungi can act on a wide range of PCB metabolites, emphasizing their potential for bioremediation.

THE SOLUBLE PROTEINS OF THE MUSCLE TISSUE OF THE HADDOCK

1931 ◽  
Vol 6 (1) ◽  
pp. 1-11 ◽  
Author(s):  
J. F. LOGAN
Keyword(s):  
Sodium Chloride ◽  
Aqueous Solutions ◽  
Muscle Tissue ◽  
Soluble Protein ◽  
Potassium Phosphate ◽  
Extraction Methods ◽  
Water Soluble ◽  
Tabular Form ◽  
Water Soluble Protein ◽  
Isoelectric Points

As a contribution to the chemistry of muscle tissue, the solubility of the protein of haddock muscle in aqueous solutions of sodium chloride and neutral potassium phosphate, respectively, was determined. The results are expressed in tabular form and graphically in the form of solubility curves. A water-soluble protein and also a salt-soluble protein were isolated from dialyzed haddock muscle by extraction methods. These proteins were obtained in a comparatively pure condition by precipitation from solution in the region of their isoelectric points.

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