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Biosorption of alpacide blue from aqueous solution by lignocellulosic biomass: Luffa cylindrica fibers Texte intégral
2016
Kesraoui, Aida | Moussa, Asma | Ali, Ghada Ben | Seffen, Mongi
The aim of the present work is to develop an effective and inexpensive pollutant-removal technology using lignocellulosic fibers: Luffa cylindrica, for the biosorption of an anionic dye: alpacide blue. The influence of some experimental parameters such as pH, temperature, initial concentration of the polluted solution, and mass of the sorbent L. cylindrica on the biosorption of alpacide blue by L. cylindrica fibers has been investigated. Optimal parameters for maximum quantity of biosorption dye were achieved after 2 h of treatment in a batch system using an initial dye concentration of 20 mg/L, a mass of 1 g of L. cylindrica fibers, and pH 2. In these conditions, the quantity of dye retained is 2 mg/g and the retention rate is 78 %. Finally, a mathematical modeling of kinetics and isotherms has been used for mathematical modeling; the model of pseudo-second order is more appropriate to describe this phenomenon of biosorption. Concerning biosorption isotherms, the Freundlich model is the most appropriate for a biosorption of alpacide blue dye by L. cylindrica fibers.
Afficher plus [+] Moins [-]Heavy metals in surface sediments of the shallow lakes in eastern China: their relations with environmental factors and anthropogenic activities Texte intégral
2016
Zhang, Wenqiang | Jin, Xin | Di, Zhenzhen | Zhu, Xiaolei | Shan, Baoqing
The aquatic environment is affected by heavy metal pollution. This study was conducted to test the hypothesis that environmental factors and anthropogenic activities influence the distributions and the risks posed by heavy metals in surface sediments in shallow lakes in eastern China, which is an area affected by rapid urbanization, industrialization, and population growth. Total Cd, Cr, Cu, Ni, Pb, Se, and Zn concentrations in sediment samples were determined using inductively coupled plasma optical emission spectrometry. The I gₑₒ showed that sediments in the lakes were moderately polluted with Cr, Cu, Pb, and Zn, and the EF method showed that Cd and Se were significantly enriched in lakes. The heavy metals were found to pose moderate risks in most of the lakes, except for Gaoyou Lake, Honghu Lake, Poyang Lake, and Weishan Lake. The RI method indicated that very high risks were posed in Dongting Lake and Poyang Lake. Cd was found to pose much higher levels of risk than the other metals. Significant correlations were found between the heavy metal concentrations and the total carbon, nitrogen, phosphorus, and sulfur concentrations. The gross domestic product represented anthropogenic activities well. The gross domestic product of an area and the gross domestic products of primary and secondary industries in an area all had significant relationships with the concentrations of Cu and Pb, indicating that anthropogenic activities have different impacts on pollution with different heavy metals. The gross domestic product index was found to be a driving force behind the pollution of lakes with heavy metals.
Afficher plus [+] Moins [-]Variability in the levels of 3-phenoxybenzoic acid by age, gender, and race/ethnicity for the period of 2001–2002 versus 2009–2010 and its association with thyroid function among general US population Texte intégral
2016
Jain, Ram B.
Data from National Health and Nutrition Examination Survey for the years 2007–2008 were used to evaluate the impact of the observed levels of 3-phenoxybenzoic acid (3-PBA) in urine on the levels of thyroid hormones in serum for those aged ≥12 years. There was no evidence of any association between the levels of 3-PBA and thyroid function. As compared to their levels in 2001–2002, levels of 3-PBA rose (p ≤ 0.03) in 2009–2010 for children, adolescents, adults aged 20–64 years, males, females, non-Hispanic whites, non-Hispanic blacks, Mexican Americans, non-smokers, and smokers. Rise in the levels of 3-PBA among children aged 6–11 years was higher than the similar rise in all other demographic groups. Since the levels of 3-PBA are still on the rise, previously observed adverse health effects among children associated with the levels of 3-PBA require that additional preventive measures be put in place to protect them from exposure to pyrethroids.
Afficher plus [+] Moins [-]Combined promoting effects of low-Pd-containing and Cu-doped LaCoO3 perovskite supported on cordierite for the catalytic combustion of benzene Texte intégral
2016
Chen, Y. W. | Li B., | Niu, Q. | Li, L. | Kan, J. W. | Zhu, S. M. | Shen, S. B.
The catalytic activities for benzene oxidation and resistance to SO₂ poisoning were tested for a series of Pd/La-Cu-Co-O/cordierite catalysts, which were prepared using a multiple-step impregnation method. The XRD, SEM, and IR characterization techniques were performed to investigate the relationship between the catalytic performance and its physicochemical properties. When Pd/La-Cu-Co-O/cordierite catalysts with Pd loadings of 0.06 and 0.08 % were prepared at a calcination temperature of 500 °C for 5 h, they exhibited similar catalytic activity and sulfur resistance. When the concentration of benzene was 1500 ppm and the GHSV was 20000 h⁻¹, the benzene conversion was above 95 % at a reaction temperature of 350 °C in SO₂ existing at 100 ppm. These results were mainly attributed to the cooperation between La-Cu-Co-O perovskite and the noble metal Pd. Specifically, the addition of copper can strengthen the catalytic activity of La-Co-O/cordierite catalysts by decreasing the crystalline size of the active ingredients. A moderate Pd addition can drastically improve the sulfur resistance and further improve the catalytic activity of the La-Cu-Co-O/cordierite catalyst.
Afficher plus [+] Moins [-]Spatial distribution, health risk assessment, and isotopic composition of lead contamination of street dusts in different functional areas of Beijing, China Texte intégral
2016
Han, Lanfang | Gao, Bo | Wei, Xin | Xu, Dongyu | Gao, Li
Street dusts from heavy density traffic area (HDTA), tourism area (TA), residential area (RA), and educational area (EA) in Beijing were collected to explore the distribution, health risk assessment, and source of lead (Pb). The average concentration of Pb in TA was the highest among the four areas. Compared with other cities, Pb concentrations in Beijing were generally at moderate or low levels. The average value (14.05) of ecological risk index (RI) indicated that Pb was at “low pollution risk” status. According to the calculation on hazard index (HI), the ingestion of dust particles of children and adults was the major route of exposure to street dusts in four studied areas, followed by dermal contact. The lower values of HI than 1 further suggested that non-carcinogenic risks of Pb in the street dusts were in the low range. Comparing ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁷Pb ratios of street dusts with other environmental samples, it was found that atmospheric deposition of coal combustion dust might be the main pathway for anthropogenic Pb input to the street dusts in four functional areas.
Afficher plus [+] Moins [-]A critical review of the development, current hotspots, and future directions of Lake Taihu research from the bibliometrics perspective Texte intégral
2016
Zhang, Yunlin | Yao, Xiaolong | Qin, Boqiang
Lake Taihu, as the important drinking water source of the Yangtze River Delta urban agglomeration and the third largest freshwater lake in China, has experienced serious lake eutrophication and water quality deterioration in the past three decades. Growing scientific, political, and public attention has been given to the water quality of Lake Taihu. This study aimed to conduct a comparative quantitative and qualitative analysis of the development, current hotspots, and future directions of Lake Taihu research using a bibliometric analysis of eight well-studied lakes (Lake Taihu, Lake Baikal, Lake Biwa, Lake Erie, Lake Michigan, Lake Ontario, Lake Superior and Lake Victoria) around the world based on the Science Citation Index (SCI) database. A total of 1582 papers discussing Lake Taihu research were published in 322 journals in the past three decades. However, the first paper about Lake Taihu research was not found in the SCI database until 1989, and there were only zero, one, or two papers each year from 1989 to 1995. There had been rapid development in Lake Taihu research since 1996 and a sharp increase in papers since 2005. A keyword analysis showed that “sediment,” “eutrophication”, “Microcystis aeruginosa”, “cyanobacterial blooms”, and “remote sensing” were the most frequently used keywords of the study subject. Owing to its significant impact on aquatic ecosystems, a crucial emphasis has been placed on climate change recently. In addition, the future focuses of research directions, including (1) environmental effects of physical processes; (2) nutrient cycles and control and ecosystem responses; (3) cyanobacteria bloom monitoring, causes, forecast and management; (4) eutrophication and climate change interactions; and (5) ecosystem degradation mechanism and ecological practice of lake restoration, are presented based on the keyword analysis. Through multidisciplinary fields (physics, chemistry, and biology) cross and synthesis study of Lake Taihu, the development of shallow lake limnology will be largely promoted.
Afficher plus [+] Moins [-]Microbial fuel cell assisted nitrate nitrogen removal using cow manure and soil Texte intégral
2016
Vijay, Ankisha | Vaishnava, Monika | Chhabra, Meenu
Microbial fuel cells (MFCs) are emerging wastewater treatment systems with a proven potential for denitrification. In this study, we have developed a high-rate denitrifying MFC. The anode consisted of cow manure and fruit waste and the cathode consisted of cow manure and soil. The initial chemical oxygen demand (COD)/nitrate nitrogen (NO₃ ⁻-N) was varied from 2 to 40 at the cathode while keeping the anode ratio fixed at 100. NO₃ ⁻-N removal rate of 7.1 ± 0.9 kg NO₃ ⁻-N/m³ net cathodic compartment (NCC)/day was achieved at cathode COD/NO₃ ⁻-N ratio 7.31 with the current density of 190 ± 9.1 mA/m² and power density of 31.92 ± 4 mW/m² of electrode surface area. We achieved an open-circuit voltage (OCV) of 410 ± 20 mV at initial cathodic NO₃ ⁻-N of 0.345 g/l. The cathode COD/NO₃ ⁻-N ratio had a significant influence on MFC’s OCV and nitrate removal rate. Lower OCV (<150 mV) and NO₃ ⁻-N removal rates were observed at COD/NO₃ ⁻-N ratio >12 and <7. Experiments done at different cathode pH values indicated that the optimum pH for denitrification was 7. Under optimized biochemical conditions, nitrate removal rate of 6.5 kg NO₃ ⁻-N/m³ net cathodic compartment (NCC)/day and power density of 210 mW/m² were achieved in a low resistance MFC. The present study thus demonstrates the utility of MFCs for the treatment of high nitrate wastes.
Afficher plus [+] Moins [-]Salt stress-induced modulations in the shoot proteome of Brassica juncea genotypes Texte intégral
2016
Yousuf, Peerzada Yasir | Ahmad, Altaf | Ganie, Arshid Hussain | Iqbal, Muhammad
Indian mustard [Brassica juncea (L.) Czern and Coss] is cultivated mainly in the northwestern agroclimatic region of India and suffers huge losses in productivity due to salinization. In an effort to figure out adaptation strategies of Indian mustard to salt stress, we conducted a comparative proteome analysis of shoots of its two genotypes, with contrasting sensitivity to salt stress. Differential expression of 21 proteins was observed during the two-dimensional electrophoresis (2DE). The identified salt-stress-responsive proteins were associated with different functional processes including osmoregulation, photosynthesis, carbohydrate metabolism, ion homeostasis, protein synthesis and stabilization, energy metabolism, and antioxidant defense system. Salt-tolerant genotype (CS-52) showed a relatively higher expression of proteins involved in turgor regulation, stabilization of photosystems and proteins, and salt compartmentalization, as compared to salt-sensitive genotype (Pusa Varuna). Our results suggest that modulating the expression of salt-responsive proteins can pave the way for developing salt tolerance in the Indian mustard plants.
Afficher plus [+] Moins [-]Degradation of dibutyl phthalate (DBP) by UV-254 nm/H2O2 photochemical oxidation: kinetics and influence of various process parameters Texte intégral
2016
Wang, Dong | Duan, Xiaodi | He, Xuexiang | Dionysiou, Dionysios D.
Degradation of dibuytl phthalate (DBP), a plasticizer and also a widely distributed endocrine disruptor, by UV-254 nm/H₂O₂ advanced oxidation process (AOP) was investigated in this study. A significant DBP removal of 77.1 % at an initial concentration of 1.0 μM was achieved at UV fluence of 160 mJ/cm², initial H₂O₂ dosage of 1.0 mM, and pH of 7.6 ± 0.1. The DBP degradation exhibited a pseudo-first-order reaction kinetic pattern, with the rate constants linearly increasing with increasing H₂O₂ dosage while decreasing with increasing initial DBP concentration and pH value in a specific range. DBP destruction was significantly inhibited in the presence of alkalinity and natural organic matter (NOM), two known factors that should be taken a serious consideration of in the research and design of UV/H₂O₂-based AOPs. Presence of common inorganic anions (i.e., Cl⁻, SO₄ ²⁻, and NO₃ ⁻) and metal cations (i.e., Fe³⁺ and Zn²⁺) had a slight impact on the degradation of DBP, although Cu²⁺ could improve the degradation efficiency even at a concentration as low as 0.01 mg/L, suggesting a strong potential of applying UV/H₂O₂ for the removal of DBP with an environmental relevant level of copper.
Afficher plus [+] Moins [-]Elemental sulfur in sediments: analytical problems Texte intégral
2016
Rogowska, Justyna | Sychowska, Joanna | Cieszynska-Semenowicz, Monika | Wolska, Lidia
In the paper, a modified method for elemental sulfur (S₈) determining using gas chromatography coupled with mass spectrometry (GC-MS) is proposed with estimation of selected validation parameters. The aim of this work was a review of problems associated with the determination of S₈ and selection of the most optimal conditions for S₈ analysis with GC-MS. The presented studies have shown that the temperature of the injector and the chromatographic column during S₈ determination should not exceed 180 °C. At temperatures over 180 °C, the sulfur S₈ is decomposed to the other sulfur species such as S₂, S₃, S₄, S₅, and S₆. During decreasing injector and column temperature below 180 °C the chromatographic peak eluted as S₈ is badly extended and asymmetric. To minimize the problems of S₈ decomposition to other sulfur species during chromatographic process also other parameters of the GC-MS have been selected. In order to apply the proposed method for real sediments samples, determination of sulfur S₈ in bottom sediments, collected in the Gulf of Gdansk (southern Baltic Sea), has been performed. The concentration of S₈ fell in the range from below the limit of detection to 0.1432 ± 0.0095 mg/g d.w. The research has also shown that addition of approx. 200 mg of activated copper is effective for removing sulfur from bottom sediment extracts.
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