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.

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.

scholarly journals Toward Isolation of Palytoxins: Liquid Chromatography Coupled to Low- or High-Resolution Mass Spectrometry for the Study on the Impact of Drying Techniques, Solvents and Materials

Toxins ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 650
Author(s):  
Antonia Mazzeo ◽  
Michela Varra ◽  
Luciana Tartaglione ◽  
Patrizia Ciminiello ◽  
Zita Zendong ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
High Resolution ◽  
Large Scale ◽  
High Resolution Mass Spectrometry ◽  
Degradation Products ◽  
Pure Water ◽  
Skin Contact ◽  
The Stability ◽  
The Impact

Palytoxin (PLTX) and its congeners are emerging toxins held responsible for a number of human poisonings following the inhalation of toxic aerosols, skin contact, or the ingestion of contaminated seafood. Despite the strong structural analogies, the relative toxic potencies of PLTX congeners are quite different, making it necessary to isolate them individually in sufficient amounts for toxicological and analytical purposes. Previous studies showed poor PLTX recoveries with a dramatic decrease in PLTX yield throughout each purification step. In view of a large-scale preparative work aimed at the preparation of PLTX reference material, we have investigated evaporation as a critical—although unavoidable—step that heavily affects overall recoveries. The experiments were carried out in two laboratories using different liquid chromatography-mass spectrometry (LC-MS) instruments, with either unit or high resolution. Palytoxin behaved differently when concentrated to a minimum volume rather than when evaporated to complete dryness. The recoveries strongly depended on the solubility as well as on the material of the used container. The LC-MS analyses of PLTX dissolved in aqueous organic blends proved to give a peak intensity higher then when dissolved in pure water. After drying, the PLTX adsorption appeared stronger on glass surfaces than on plastic materials. However, both the solvents used to dilute PLTX and that used for re-dissolution had an important role. A quantitative recovery (97%) was achieved when completely drying 80% aqueous EtOH solutions of PLTX under N2-stream in Teflon. The stability of PLTX in acids was also investigated. Although PLTX was quite stable in 0.2% acetic acid solutions, upon exposure to stronger acids (pH < 2.66), degradation products were observed, among which a PLTX methyl-ester was identified.

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.

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