scholarly journals Degradation of 1H-benzotriazole using vacuum ultraviolet: a prospective treatment method for micro-pollutants

2019 ◽  
Vol 80 (4) ◽  
pp. 773-783 ◽  
Author(s):  
Jinshao Ye ◽  
Han Hu ◽  
Ya Chen ◽  
Yujia Chen ◽  
Huase Ou
Keyword(s):  
Vacuum Ultraviolet ◽  
Degradation Products ◽  
Water Solution ◽  
Pure Water ◽  
Radical Reaction ◽  
Treatment Method ◽  
Environmental Water ◽  
Open Loop ◽  
Radical Trapping ◽  
Uv C

Abstract Benzotriazoles (BTs) attract increasing concerns because of abundant presence in environmental water bodies. In this study, degradation of 1H-benzotriazole (1H-BT) was performed by a customized vacuum ultraviolet (VUV) device emitting 185 + 254 nm (VUV/UV-C) irradiation. Degradation of 1H-BT presented an apparent rate constant reached 8.17 × 10−4 s−1. Degradation mechanisms included 185 + 254 nm photodegradation and radical reaction. The later one may be the predominant one, which presented a k·OH-1H-BT at (7.3 ± 0.8) × 109 M−1 s−1. Effects of anions revealed that VUV interception and radical trapping were the dominant restraining factors. Degradation of 1H-BT can be attributed to VUV induced radical-based oxidation. Radical-induced addition, substitution and fracture generated abundant hydroxylated and open-loop products during 10–45 min. Identification using reactive oxygen species and apoptosis in Escherichia coli was conducted. Variations of these two indicators revealed that the incomplete degradation products presented higher toxicities than 1H-BT, and a further mineralization reduced their toxicities. In the pure water solution with little impurities, VUV can induce efficient degradation of 1H-BT, suggesting its potential for eliminating and detoxifying MPs.

Persulfate-mediated Photocatalytic Degradation of Ciprofloxacin in Water Using Ultraviolet Light and Zero-valent Aluminum

2020 ◽  
Vol 1 (1) ◽  
pp. 67-76
Author(s):  
Tugba Olmez-Hanci ◽  
Idil Arslan-Alaton
Keyword(s):  
Surface Water ◽  
Acute Toxicity ◽  
Vibrio Fischeri ◽  
Degradation Products ◽  
Pure Water ◽  
Inorganic Ions ◽  
Toxicity Tests ◽  
Resistant Bacteria ◽  
Distilled Water ◽  
Uv C

Aims: The study aimed at assessing the effectiveness of the PS/UV-C, PS/ZVA and PS/ZVA/UV-C processes in terms of ciprofloxacin, a fluoroquinolone type commercially important antibiotic, and toxicity abatements in raw surface water (RSW) and distilled water (DW). Background: The occurrence of ciprofloxacin (CIP), the most widely prescribed second-generation fluoroquinolone antibiotic, even at trace level (ng/L) gives rise to antibiotic resistant bacteria and resistance genes, which can further impair the selection of genetic variants of microorganisms and impose adverse effect on human health. Objective: The degradation and detoxification of ciprofloxacin with UV-C (PS/UV-C) and ZVA (PS/ZVA) activated PS oxidation systems were investigated in distilled water (DW) and raw (untreated) surface water (RSW) samples. Moreover, CIP degradation with the PS/ZVA/UV-C heterogeneous photochemical treatment combination was also studied. Methods: The process performances of the investigated treatment systems were evaluated in terms of CIP abatement and PS consumption rates as well as dissolved organic carbon (DOC) removal efficiencies. The influence of common inorganic ions and natural organic matter (NOM) on CIP degradation was evaluated. Radical quenching experiments were conducted using probe compounds in order to elucidate the dominant reaction mechanism. In addition, acute toxicity of the original CIP and its degradation products were questioned by employing Vibrio fischeri (V. fischeri), the marine photobacterium, under optimized treatment conditions. Results: CIP was completely degraded in distilled water (DW) and raw (untreated) surface water (RSW) samples after 15 min of treatment with the PS/UV-C process (PS=0.25mM; pH=3; UVC= 2.7W/m2). PS/UV-C experiments conducted with RSW at its natural pH (=8.5) resulted in 98% CIP and practically no DOC removal whereas 56% DOC was removed at pH 3 after 120 min. Radical quenching studies revealed that sulfate radicals prevailed over hydroxyl radicals. CIP degradation was significantly inhibited by the presence of humic acid due to the effect of UV absorption and free radical quenching. Acute toxicity tests with V. fischeri exhibited fluctuating trends throughout the investigated processes and did not change appreciably after 120 min of oxidation. Conclusion: The results of this study demonstrated that PS/UV-C is superior to the PS/ZVA and PS/ZVA/UV-C treatment systems for both DW and RSW samples in terms of CIP removal rates. No additional positive effect was evident for simultaneous catalytic and photochemical PS activation (PS/ZVA/UV-C treatment system). It could be also demonstrated that the selected oxidation processes conducted in pure water might give an idea about the advanced treatment systems but realistic conditions with actual water/wastewater matrices still need to be further investigated to verify their feasibility and ecotoxicological safety.

Photodegradation of nonylphenol polyethoxylates in aqueous solution

2009 ◽  
Vol 6 (2) ◽  
pp. 185 ◽  
Author(s):  
Lei Wang ◽  
Hongwen Sun ◽  
Yinghong Wu ◽  
Guolan Huang ◽  
Shugui Dai
Keyword(s):  
Mass Spectrometry ◽  
Humic Acid ◽  
Environmental Concern ◽  
Degradation Products ◽  
Water Solution ◽  
Pure Water ◽  
Photodegradation Efficiency ◽  
Ionisation Mass Spectrometry ◽  
Oxidative Pathway ◽  
Important Pathway

Environmental context. Nonylphenol polyethoxylates (NPEOs) are widely used non-ionic surfactants, and they cause environmental concern because some metabolites of NPEOs possess endocrine-disrupting activities. Photodegradation is an important pathway for NPEOs degradation, and different degradation products may lead to different environmental risks. The present paper looks at the kinetics and pathways of NPEO photodegradation in aqueous solutions, focussing on the effects of humic acid, H2O2, and FeIII. We found that the presence of different chemicals led to different degradation pathways, and a new mechanism is proposed. Abstract. To further elucidate the mechanism of photoinduced degradation of nonylphenol polyethoxylates (NPEOs) in aqueous environments, two different light systems, UVA and simulated sunlight, were used, and the effects of humic acid, H2O2, and FeIII were investigated. The 96-h degradation efficiencies of NPEOs in pure water solution were found to be 36.6 and 22.6% under UVA and SSL irradiation respectively. The presence of humic acid and FeIII in solution increased the photodegradation efficiency of NPEOs to different extents. The proportion of short-chain NPEOs in the NPEOn mixture was found to increase significantly in the solution containing FeIII, whereas this phenomenon was not observed in pure water and solutions containing H2O2 or humic acid. The result of NPEO3 photodegradation experiments indicated that FeIII in solution led to an ethoxylate-reduction pathway. Dicarboxylated formate ethoxylates were proposed as the intermediate products of NPEO photodegradation through an oxidative pathway based on the analytical results of liquid chromatography–electrospray ionisation–mass spectrometry and tandem mass spectrometry. Different mechanisms of NPEO photodegradation were elucidated.

Bionanomaterials: Thermal Stability of the Oleic Acid / alpha- and beta-cyclodextrin Complexes

2008 ◽  
Vol 59 (9) ◽  
Author(s):  
Daniel I. Hadaruga ◽  
Nicoleta G. Hadaruga ◽  
Anca Hermenean ◽  
Adrian Rivis ◽  
Vasile Paslaru ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Oleic Acid ◽  
Solution Method ◽  
Degradation Products ◽  
Water Solution ◽  
Fatty Acid Esters ◽  
Cyclodextrin Complexes ◽  
Free Oleic Acid ◽  
Thermal Stability Of ◽  
Acid Esters

This paper presents the thermal stability of the oleic acid encapsulated in a- and b - cyclodextrin. The complexation of the oleic acid was achieved by the ethanol-water solution method and the nanoparticles were analyzed by DSC. The free oleic acid and the encapsulated one were subjected to the thermal degradation in the range of 50-150�C and the degradation products were identified and quantified by GC-MS analysis of the fatty acid esters obtained by deriving with methanol/boron trifluoride, both for free compounds and for the encapsulated ones. The oleic acid complexes were very stable in this range of temperature.

Association of Graft Copolymers of Alkyl Methacrylates with α-Methyl-ω-hydroxy-poly(oxyethylene) ethacrylates

1995 ◽  
Vol 60 (11) ◽  
pp. 1971-1985 ◽  
Author(s):  
Čestmír Koňák ◽  
Zdeněk Tuzar ◽  
Pavla Kopečková ◽  
Joseph D. Andrade ◽  
Jindřich Kopeček
Keyword(s):  
Light Scattering ◽  
Graft Copolymers ◽  
Water Solution ◽  
Pure Water ◽  
Solution Properties ◽  
Monomer Composition ◽  
Special Procedure ◽  
Methyl Cellosolve ◽  
Hexyl Methacrylate ◽  
Alkyl Methacrylates

Solution properties of the statistical copolymers of alkyl methacrylates (AMA) with α-methyl-ω-hydroxy-poly(oxyethylene) methacrylates (MPOEMA) (nonionic polysoaps) were studied using static and dynamic ligh scattering as a function of monomer composition and concentration in aqueous and methyl cellosolve solutions. The solubility of the copolymers in water was found to be dependent on molar contant of AMA. While copolymers with low content of hexyl methacrylate (HMA) (0 and 20 mole %) were directly soluble in water, forming true solutions with a low content of large swollen aggregates, copolymers with a higher content of HMA or lauryl methacrylate (LMA) were not directly dispersable in water. A special procedure, the stepwise dialysis from methyl cellosolve solutions against water, had to be used to prepare them in the pseudomicellar form. The copolymers were directly soluble in methyl cellosolve and its water solution containing up to 60 vol.% of water. Nevertheless, the light scattering experiments were dominated by light scattering of swollen particles of aggregated copolymer molecules. The copolymers were not soluble in the mixtures containing 70-100 vol.% of water. Paramaters of aggregates in the mixture with 60 vol.% of water and in pure water were found to be very similar.

scholarly journals Behavior and properties of water in silicate melts under deep mantle conditions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bijaya B. Karki ◽  
Dipta B. Ghosh ◽  
Shun-ichiro Karato
Keyword(s):  
Electrical Conductivity ◽  
Molar Volume ◽  
Water Solution ◽  
Pure Water ◽  
Electrical Conductance ◽  
Water Structure ◽  
Bulk Water ◽  
Silicate Melts ◽  
Pressure Regime ◽  
Low Pressures

AbstractWater (H2O) as one of the most abundant fluids present in Earth plays crucial role in the generation and transport of magmas in the interior. Though hydrous silicate melts have been studied extensively, the experimental data are confined to relatively low pressures and the computational results are still rare. Moreover, these studies imply large differences in the way water influences the physical properties of silicate magmas, such as density and electrical conductivity. Here, we investigate the equation of state, speciation, and transport properties of water dissolved in Mg1−xFexSiO3 and Mg2(1−x)Fe2xSiO4 melts (for x = 0 and 0.25) as well as in its bulk (pure) fluid state over the entire mantle pressure regime at 2000–4000 K using first-principles molecular dynamics. The simulation results allow us to constrain the partial molar volume of the water component in melts along with the molar volume of pure water. The predicted volume of silicate melt + water solution is negative at low pressures and becomes almost zero above 15 GPa. Consequently, the hydrous component tends to lower the melt density to similar extent over much of the mantle pressure regime irrespective of composition. Our results also show that hydrogen diffuses fast in silicate melts and enhances the melt electrical conductivity in a way that differs from electrical conduction in the bulk water. The speciation of the water component varies considerably from the bulk water structure as well. Water is dissolved in melts mostly as hydroxyls at low pressure and as –O–H–O–, –O–H–O–H– and other extended species with increasing pressure. On the other hand, the pure water behaves as a molecular fluid below 15 GPa, gradually becoming a dissociated fluid with further compression. On the basis of modeled density and conductivity results, we suggest that partial melts containing a few percent of water may be gravitationally trapped both above and below the upper mantle-transition region. Moreover, such hydrous melts can give rise to detectable electrical conductance by means of electromagnetic sounding observations.

Identification of degradation products of terbutol in environmental water from golf courses

1995 ◽  
Vol 43 (6) ◽  
pp. 1712-1717 ◽  
Author(s):  
Toshinari Suzuki ◽  
Kumiko Yaguchi ◽  
Kazuo Ohnishi ◽  
Tetsuya Suga
Keyword(s):  
Degradation Products ◽  
Environmental Water ◽  
Golf Courses

scholarly journals Testing for ion-mediated enhancement of the hydraulic conductance of the leaf xylem in diverse angiosperms

2017 ◽  
Vol 4 ◽  
pp. e004 ◽  
Author(s):  
Christine Scoffoni ◽  
Grace John ◽  
Herve Cochard ◽  
Lawren Sack
Keyword(s):  
Water Solution ◽  
Pure Water ◽  
Xylem Sap ◽  
Hydraulic Conductance ◽  
Membrane Pores ◽  
Whole Plant ◽  
Pit Membrane ◽  
Major Bottleneck ◽  
The Difference ◽  
Xylem Conduits

Replacing ultra-pure water solution with ion solution closer to the composition of natural xylem sap increases stem hydraulic conductance by up to 58%, likely due to changes in electroviscosity in the pit membrane pores. This effect has been proposed to contribute to the control of plant hydraulic and stomatal conductance and potentially to influence on carbon balance during dehydration. However, this effect has never been directly tested for leaf xylem, which constitutes a major bottleneck in the whole plant. We tested for an ion-mediated increase in the hydraulic conductance of the leaf xylem (Kx) for seven species diverse in phylogeny and drought tolerance. Across species, no significant changes in Kx were observed between 0 and 15 mM KCl. We further tested for an effect of ion solution during measurements of Kx vulnerability to dehydration in Quercus agrifolia and found no significant impact. These results for leaf xylem contrast with the often strong ion effect reported for stems, and we suggest several hypotheses to account for the difference, relating to the structure of xylem conduits across vein orders, and the ultrastructure of leaf xylem pores. A negligible ion response in leaves would weaken xylem sap ion-mediated control of plant hydraulic conductance, facilitating modeling of whole plant hydraulic behavior and its influence on productivity.

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.

Nitric Oxide Radical Trapping Analysis on Vacuum-Ultraviolet Treated Polymers

1998 ◽  
Vol 31 (22) ◽  
pp. 7613-7617 ◽  
Author(s):  
R. Wilken ◽  
A. Holländer ◽  
J. Behnisch
Keyword(s):  
Nitric Oxide ◽  
Vacuum Ultraviolet ◽  
Radical Trapping ◽  
Nitric Oxide Radical

An Experimental Study for NOx - Emission Reduction with Urea-SCR Technology in Vehicular Diesel Engines

2011 ◽  
Vol 71-78 ◽  
pp. 2089-2093 ◽  
Author(s):  
Qian Wang ◽  
Ming Xing Zhou ◽  
Bao Yi Wang
Keyword(s):  
Fuel Consumption ◽  
Control Strategy ◽  
Catalytic Reduction ◽  
Water Solution ◽  
Open Loop ◽  
Loop Control ◽  
Consumption Ratio ◽  
Future Emission ◽  
System Configurations ◽  
Scr System

In order to fulfill future emission standards for middle and heavy-duty vehicles like state Ⅳ and Ⅴ, advanced measures on exhaust gas and engine functionality are required. Selective Catalytic Reduction (SCR) technology is the unique technology currently which can improve the emission and reduce fuel consumption simultaneously. Firstly the reductants and its chemical reactions, SCR system configurations and its working principle and urea dosing control strategy are introduced. Then tests are conducted on a diesel engine with SCR system at bench. The results of ESC cycle show that NOx emission is decreased by more than 67% with the open-loop control strategy. Additionally, the urea and fuel consumption and ammonia leakage have been compared and analyzed respectively, the experiment data indicates that the urea water solution consumption ratio is only 5.7% of fuel for this SCR system, while its average ammonia slip is below 5 ppm.

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