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Photocatalytic oxidation of toluene and isopropanol by LaFeO3/black-TiO2 Texte intégral
2019
Lee, Yun-En | Chung, Wei-Chieh | Chang, Moo-Been
Large amount of volatile organic compounds (VOCs) are emitted from industrial, mobile, and domestic sources, causing adverse effects on human health and environment. Among VOCs, toluene and isopropanol (IPA) are commonly used as solvent, soldering flux, and spray paint and their emissions need to be reduced. Several VOCs abatement technologies are available to reduce VOC emission and photocatalytic oxidation of VOC is regarded as a viable technique due to its advantage of utilizing solar energy. TiO₂ has been investigated for its oxidation capability toward VOCs because of its good photocatalytic activity. However the utilization is limited to UV due to its wider bandgap; furthermore, its fast recombination rate of electron-hole pair reduces the oxidation rate of VOCs. Black-TiO₂ and perovskite-type photocatalyst such as LaFeO₃ can be applied to enhance photocatalytic activity due to narrower bandgap and longer electron-hole pair lifetime. In this study, black-TiO₂ and LaFeO₃ are prepared and investigated for their photocatalytic oxidation rates toward toluene and IPA. Results show that toluene removals achieved with black-TiO₂ and LaFeO₃ are 89% and 98% while IPA removals are 90% and 94%, respectively. Both photocatalysts show better photocatalytic activity than TiO₂ and good absorption capability toward visible light. Graphical abstract
Afficher plus [+] Moins [-]Congo red dye diversely affects organisms of different trophic levels: a comparative study with microalgae, cladocerans, and zebrafish embryos Texte intégral
2019
Global consumption of synthetic dyes is roughly 7 × 10⁵ tons per year, of which the textile industry expends about two-thirds. Consumption of synthetic dyes produces large volumes of wastewater discharged into aquatic ecosystems. Colored effluents produce toxic effects in the hydrobionts, reduce light penetration, and alter the photosynthetic activity, causing oxygen depletion, among other effects. Some dyes, such as Congo red (CR), are elaborated with benzidine, a known carcinogenic compound. Information regarding dye toxicity in aquatic ecosystems is scarce; therefore, our study was aimed at evaluating the toxicity of CR on a battery of bioassays: the microalga Pseudokirchneriella subcapitata, the cladocerans Daphnia magna and Ceriodaphnia rigaudi, and the zebrafish Danio rerio. P. subcapitata was the most sensitive species to CR (IC₅₀, 3.11 mg L⁻¹); in exposed individuals, population growth was inhibited, but photosynthetic pigments and macromolecule concentrations were stimulated. D. magna was tolerant to high dye concentrations, the determined LC₅₀ (322.9 mg L⁻¹) is not an environmentally relevant value, but for C. rigaudi, LC₅₀ was significantly lower (62.92 mg L⁻¹). In zebrafish embryos, exposure to CR produced yolk sac edema, skeletal deformities, and stopped larvae hatching; lack of heart beating was the only observed lethal effect. CR affected organisms of different trophic levels diversely. Particularly, the effects observed in microalgae confirm the vulnerability of primary producers to dye-polluted wastewaters, because dyes produced toxic effects and interfered with photosynthesis. Different cladoceran species displayed different acute effects; thus, species sensitivity must also be considered when toxicity of dyes is assessed. Inhibition of fish larvae hatching is a significant effect not previously reported that warns about the toxicity of dyes in fish population dynamics. Synthetic azo colorants should be considered as emerging pollutants because they are discharged into the aquatic environment and are not currently included in the environmental regulation of several countries.
Afficher plus [+] Moins [-]Effects of secondary metabolites produced by different cyanobacterial populations on the freshwater zooplankters Brachionus calyciflorus and Daphnia pulex Texte intégral
2019
Pawlik-Skowrońska, Barbara | Toporowska, Magdalena | Mazur-Marzec, Hanna
Cyanobacterial blooms in eutrophic water bodies are a worldwide problem. Combined effects of mixtures of secondary metabolites produced by different cyanobacterial species on aquatic fauna are still not well recognised. We compared the survivorship of Brachionus calyciflorus Pallas (Rotifera) and Daphnia pulex Leyding (Cladocera) exposed to pure microcystin LR (MC-LR), anatoxin-a (ANTX) and to five extracts obtained from bloom-forming cyanobacteria Microcystis, Planktothrix and Dolichospermum. The obtained results revealed different response of the organisms to high concentrations of pure MC-LR, ANTX and complex cyanobacterial extracts. The extracts’ toxicity to invertebrates was higher than that exerted by pure cyanotoxins and was dependent on the composition of cyanobacterial metabolites: Microcystis spp. extract containing anabaenopeptins A and B, aeruginosamide, four variants of cyanopeptolins and five MCs was not toxic to either of the organisms, whereas Planktothrix agardhii extract (I), containing anabaenopeptins A, B, F, 915, oscillamide Y, five different aeruginosins and four variants of MC was more toxic to daphnids than to rotifers. The extracts of another P. agarhdii (II) biomass and two different biomass samples of Dolichospermum spp. also affected survivorship of the rotifer and cladoceran, however, to various extent. It strongly suggests that non-ribosomal oligopeptides, other than MCs, had essential contribution to the observed toxicity to invertebrates and their effects on particular species or populations can vary depending on the secondary metabolite profiles of cyanobacteria.
Afficher plus [+] Moins [-]Cognitive function among schoolchildren in Lebanon: association with maternal alcohol drinking and smoking during pregnancy and domestic use of detergents and pesticides during childhood Texte intégral
2019
Hallit, Souheil | Haddad, Chadia | Zeidan, Rouba Karen | Obeid, Sahar | Kheir, Nelly | Khatchadourian, Talar | Salameh, Pascale
To evaluate the relation between caregiver exposure to toxics during pregnancy and childhood and the child’s cognitive function in Lebanese children. This was a cross-sectional study conducted on Lebanese students in public and private schools from November 2017 to May 2018, enrolling 464 children. A first linear regression, taking the Cattell total score as the dependent variable and taking sociodemographic characteristics and the family history of the child as independent variables, showed that higher age (Beta = 1.65) was significantly associated with higher cognition, whereas a history of eczema in any of the parents (Beta = −7.32) was significantly associated with lower cognition in the child. A second linear regression, taking the Cattell total score as the dependent variable and taking sociodemographic characteristics and the family history of the child, and the exposure to toxics as independent variables, showed that maternal alcohol intake during pregnancy (Beta = −1.07) and detergent mixing (Beta = −1.48) were significantly associated with lower cognition in the child. A third linear regression, taking the Cattell total score as the dependent variable and taking sociodemographic characteristics and the family history of the child, the exposure to toxics and the diseases in the child as independent variables, showed that maternal alcohol intake during pregnancy (Beta = −1.07) and detergent mixing (Beta = −1.45) were significantly associated with lower cognition in the child, whereas a history of eczema in the child before the age of 2 years (Beta = 8.72) was significantly associated with higher cognition in the child. This study is the first to examine the association of a child’s prenatal exposure and their exposure during childhood to environmental toxicants with their cognitive function in Lebanon. We consider this study to be important as it shows the possible effect of cleaning products mixing and maternal alcohol consumption on cognitive functions among children in Lebanon.
Afficher plus [+] Moins [-]Combined HQSAR method and molecular docking study on genotoxicity mechanism of quinolones with higher genotoxicity Texte intégral
2019
Zhao, Xiaohui | Wang, Xiaolei | Li, Yu
Using the hologram quantitative structure-activity relationship (HQSAR) method, a quantitative model of the structure-activity relationship between the genotoxicity of quinolones towards gram-negative bacteria and structure of quinolones is constructed. A series of novel quinolones are designed, and 4 environmentally friendly quinolone derivatives are finally selected, because of their enhanced genotoxicity towards gram-negative/positive bacteria, decreased bioconcentration and increased photodegradability and biodegradability. The mechanisms underlying the genotoxicity of quinolones and its derivatives are analysed based on amino acid residues and molecular interactions. Three hydrophilic amino acids [arginine (ARG), asparagine (ASN) and aspartic acid (ASP)] play important roles in the antibacterial effects of quinolones. The introduction of highly hydrophilic groups into the C-7 position of amifloxacin (AMI) not only improved the stability of the AMI derivative-topoisomerase IV-DNA complex but also improved the antibacterial activities of AMI derivatives.
Afficher plus [+] Moins [-]Distribution characteristics and noncarcinogenic risk assessment of culturable airborne bacteria and fungi during winter in Xinxiang, China Texte intégral
2019
Yan, Xu | Qiu, Dezhi | Zheng, Shikan | Yang, Jie | Sun, Hongyan | Wei, Yue | Han, Jingru | Sun, Jianhui | Su, Xianfa
Bioaerosols are an important component of particulate matter in the atmosphere and are harmful to human health. In this study, the concentration, size distribution, and factors influencing culturable airborne bacteria and fungi in the atmosphere were investigated using a six-stage impactor device in the city of Xinxiang, China, during the winter season. The results revealed that the concentration of culturable airborne bacteria and fungi varied significantly during the sampling period: 4595 ± 3410 and 6358 ± 5032 CFU/m³, respectively. The particle sizes of the bioaerosols were mainly within stage V (1.1–2.1 μm), and fine particulate matter accounted for 45.9% ± 18.9% of airborne bacteria and 52.0% ± 18.5% of airborne fungi, respectively. With the deterioration of air quality, the concentration of airborne fungi gradually increased, and that of airborne bacteria increased when the air quality index was lower than 200 and decreased when it was higher than 200. With respect to the diurnal variation pattern of bioaerosol concentration, the highest and lowest concentrations were registered at night and noon, respectively, probably because of changes in ultraviolet radiation intensity. Bioaerosol concentration positively correlated with humidity, concentration of PM₂.₅, PM₁₀, SO₂, and NO₂ and negatively correlated with O₃ concentration. The risk of exposure of humans to the airborne bacteria was primarily associated with the respiratory inhalation pathway, and the risk of skin exposure was negligible. These results should improve our understanding of the threat of bioaerosols to public health.
Afficher plus [+] Moins [-]Identification of photoproducts of florasulam in water using UPLC-QTOF-MS Texte intégral
2019
Qiao, Yuxin | Chen, Guofeng | Ma, Chengyi | Tao, Bo | Ma, Hong | Zhang, Xiaobo | Liu, Feng
Here, we aimed to investigate florasulam photodegradation in aquatic environments under UV-visible irradiation. LC-MS/MS was used to explore the photolysis kinetics of florasulam degradation with respect to different light source types, florasulam concentrations, water sources, and pH. We also tested whether the addition of the nitrate ions, Fe³⁺, or I⁻ to the reaction solution influences florasulam photolysis kinetics. NO₃⁻ accelerates florasulam degradation at low concentrations (0.01–1 mg L⁻¹), but decreases the process at higher concentrations. At low concentrations (≤ 0.1 mg L⁻¹), Fe³⁺ enhanced florasulam photodegradation obviously. However, the addition of 0.01–10 mg L⁻¹ I⁻ decreased the degradation rate linearly. The florasulam photolysis rates in alkaline and neutral solutions were higher than that in acidic solutions. The florasulam degradation rate under mercury light irradiation was greater than that under xenon light. The rate of florasulam degradation in distilled water was greater than in tap water, lake water, and rice paddy water. As the concentration of florasulam increased, the photodegradation rate decreased. Six kinds of transformation products (TPs) were isolated and identified using UPLC/Q-TOF-MS. Based on these TPs and their evolutionary processes, we inferred the florasulam degradation mechanisms, identifying four possible florasulam degradation pathways. Cleavage of the florasulam sulfonamide bond yielded TPs2. TPs2 was intermolecularly rearranged to form a SO₂ extrusion compound, TPs3. Cleavage of the [C-F] bonds led to the formation of TPsl, TPs4, and TPs5, while hydroxylation led to the formation of TPs6. We then predicted the stability of each of the florasulam TPs in water. TPs2 and TPs3 rapidly degraded after reaching maximum concentration due to poor light stability. TPs4 and TPs6 were more photostable than florasulam (the parent compound) and may be important contributors to water pollution.
Afficher plus [+] Moins [-]Static decontamination of oil-based drill cuttings with pressurized hot water using response surface methodology Texte intégral
2019
Chen, Zhong | Li, Dongyuan | Tong, Kun | Chen, Zeliang | Chen, Hongzhen | Chen, Qiao | Xu, Yuanjian
Separating organic pollutants from oil-based drill cuttings (OBDC) is the current trend for its safe disposal. In this study, pressurized hot water extraction (PHWE) was adapted to decontaminate OBDC for the first time. Two typical OBDC samples, i.e., diesel-based drill cuttings (OBDC-A) and white oil-based drill cuttings (OBDC-B), were statically extracted in a homemade batch autoclave. Response surface methodology (RSM) with a central composite design (CCD) was applied to investigate the effects and interactive effects of three independent operating parameters (temperature, extraction time, and water volume) and to ultimately optimize the PHWE process. The results suggested that temperature is the dominant parameter, followed by water volume and extraction time. Interactive effects among the three parameters are present in the PHWE of OBDC-A but absent in the PHWE of OBDC-B. The suitable conditions for the effective PHWE of OBDC-A were found to be a temperature of 284–300 °C, water volume of 15–35 ml, and extraction time of 20–60 min. The corresponding conditions were 237–300 °C, 15–35 ml, and 20–60 min for the PHWE of OBDC-B. These different phenomena are caused by the different characteristics of the two OBDC samples. All of the polynomial models obtained from the RSM experiments are very valid and can adequately describe the relationship among the three independent operating parameters and responses. The experimental results also confirmed that PHWE is a more efficient separation technique for decontaminating OBDC than single organic solvent extraction or low-temperature thermal desorption because PHWE integrates the advantages of both these processes.
Afficher plus [+] Moins [-]Synthesis and application of ion-imprinted polymer for the determination of mercury II in water samples Texte intégral
2019
Francisco, Janaina E. | Feiteira, Fernanda N. | da Silva, Wanderson A. | Pacheco, Wagner F.
In this study, an innovative analytical methodology capable of selectively identifying and quantifying mercury contamination by the association of solid-phase extraction using ion-imprinted polymers as a sorbent phase and differential pulse anodic stripping voltammetry is proposed. To this end, the ion-imprinted polymers were synthesized and characterized by infrared spectroscopy and atomic force microscopy. The sorption capacities and the selectivity of the ion-imprinted polymers were compared to the ones related to the non-imprinted ones. Next, the experimental parameters of this solid-phase extraction method (IIP-SPE) were evaluated univariately. The selectivity of this polymeric matrix against other cations (Cd II, Pb II, and Cu II) was also evaluated. Limits of detection (LOD) and quantification (LOQ) obtained for the here proposed methodology were 0.322 μg L⁻¹ and 1.08 μg L⁻¹, respectively. Also, the precision of 4.0% was achieved. The method was finally applied to three water samples from different sources: for the Piratininga and Itaipu Lagoon waters, Hg II concentrations were below the LOQ and for Vargem River waters a concentration equal to 1.35 ± 0.07 mg L⁻¹ was determined. These results were confirmed by recovery tests, resulting in a recovery of 96.2 ± 4.0%, and by comparison with flame atomic absorption spectrometry, resulting in statistical conformity between the two methods at 95% confidence level.
Afficher plus [+] Moins [-]ESSIMAGE: a tool for the assessment of the agroecological performance of agricultural production systems Texte intégral
2019
Trabelsi, Meriam | Mandart, Elisabeth | Le Grusse, Philippe | Bord, Jean-Paul
Over the last few years, intensive agriculture has often been denounced as a source of negative effects, particularly at the environmental and health level (overexploitation of natural resources, degradation of their quality, appearance and development of several diseases, etc.). Reducing the excessive use of agricultural inputs for the protection of the environment and the preservation of human and animal health is a social requirement nowadays. Investing in more sustainable agricultural models which make it possible to reduce, or even eliminate the risks, has become urgent. A possible solution may be to resort to agroecological systems. In order to be sustainable, these new systems must be performant at the agronomic, economic, social, and environmental levels. There is a multitude of tools for assessing the sustainability of agricultural systems. These tools are inappropriate for organic and agroecological systems, and do not make it possible to measure the agroecological transition performance of farms (Trabelsi et al. Environ Sci Pollut Res 23:139–156, 2016; Trabelsi 2017). This research project aims to design a decision support tool in order to help farms throughout the agroecological transition process, to assess the performance of this transition, and to put forward improvement scenarios. Contrary to other assessment methods, ESSIMAGE (Evaluation and Simulation of Agroecological Systems) is based on both pressure and impact indicators, and takes the specificities of agricultural production systems into account. It is a dynamic tool which not only makes it possible to assess farm performance at the present moment but also to consider the future by putting forward possible alternative improvement scenarios and by simulating their consequences at a later stage. ESSIMAGE is based on the interaction of two elements: agro-environmental, social, and economic indicators, and the GIS (Geographic Information System) software. This tool has been tested as part of a CASDAR “Post-MAET Gimone” (agriculture.gouv.fr/ministere/mobilisation-collective-pour-lagroecologie.) project on the subject of “Collective mobilization for agroecology” by using farm data, most of the farms having been involved in an agro-environmental measure for the progressive reduction of phytosanitary treatments since 2008. It has made it possible to compare the agroecological performances of these farms with an optimal situation, as well as with each other. Considering the research objectives and the approaches discussed, this study is an original step in the development of agricultural management strategies in favor of agroecology.
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