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Результаты 1461-1470 из 1,955
Determination of benzotriazoles in dishwasher tabs from Germany and estimation of the discharge into German waters Полный текст
2013
Vetter, Walter | Lorenz, Joachim
A method was developed for the determination of benzotriazoles (BTs) in dishwasher tabs. BTs consist of 1H-benzotriazole and/or tolyltriazole, i.e., a technical mixture of the two isomers 4-methylbenzotriazole and 5-methylbenzotriazole (5-MBT). The method consisted of weighing of an aliquot of the tab, addition of the internal standard 5-MBT, precipitation of the soaps with CaCl₂and KOH, derivatization of the filtrate with acetic acid anhydride in a two-phase system, and analysis of the organic toluene layer by gas chromatography with mass spectrometry in the selected ion monitoring mode. Eleven of 12 different dishwasher tabs from the German market were tested positive with BTs ranging from 2 to 66 mg/tab. Dishwashing experiments were performed to show that at least 99 % of the BT amount used in the dishwasher did not remain on the dishes but was released into the wastewater treatment system. The annual release of BTs into the water system was estimated to be ~80 tons. Since 70 % or less of the BTs can be degraded in wastewater treatment plants, at least 24 tons are annually released into rivers in Germany.
Показать больше [+] Меньше [-]Synthesis of hybrid carbon nanotubes using Brassica juncea L. application to photodegradation of bisphenol A Полный текст
2013
Qu, Jiao | Luo, Chunqiu | Yuan, Xing
Hyperaccumulators contain tubular cellulose and heavy metals, which can be used as the sources of carbon and metals to synthesize nanomaterials. In this paper, carbon nanotubes (CNTs), Cu₀.₀₅Zn₀.₉₅O nanoparticles, and CNTs/Cu₀.₀₅Zn₀.₉₅O nanocomposites were synthesized using Brassica juncea L. plants, and the ultraviolet (UV)-light-driven photocatalytic degradations of bisphenol A (BPA) using them as photocatalysts were studied. It was found that the outer diameter of CNTs was around 50 nm and there were a few defects in the crystal lattice. The synthesized Cu₀.₀₅Zn₀.₉₅O nanocomposites had a diameter of around 40 nm. Cu₀.₀₅Zn₀.₉₅O nanocomposites have grown on the surface of the CNTs and the outer diameter of them was around 100 nm. The synthesized hybrid carbon nanotubes using B. juncea could enhance the efficiency of photocatalytic degradation on BPA. The complete equilibration time of adsorption/desorption of BPA onto the surface of CNTs, Cu₀.₀₅Zn₀.₉₅O nanoparticles, and CNTs/Cu₀.₀₅Zn₀.₉₅O nanocomposites was within 30, 20, and 30 min, and approximately 14.9, 8.7, and 17.4 % BPA was adsorbed by them, respectively. The combination of UV light irradiation (90 min) with CNTs, Cu₀.₀₅Zn₀.₉₅O nanoparticles, and CNTs/Cu₀.₀₅Zn₀.₉₅O nanocomposites could lead to 48.3, 75.7, and 92.6 % decomposition yields of BPA, respectively. These findings constitute a new insight for synthesizing nanocatalyst by reusing hyperaccumulators.
Показать больше [+] Меньше [-]Determination of testosterone and its photodegradation products in surface waters using solid-phase extraction followed by LC–MS/MS analysis Полный текст
2013
Vulliet, Emmanuelle | Giroud, Barbara | Marote, Pedro
The formation of several by-products from the photodegradation of testosterone was previously observed under laboratory conditions. The objectives of the manuscript were to complete the identification of testosterone’s photoproducts and to develop an analytical method for the detection of testosterone as well as its three main photoproducts in natural sunlit surface waters. To accomplish these tasks, an efficient extraction method was developed based on solid-phase extraction, followed by the use of liquid chromatography coupled to tandem mass spectrometry, a selective and sensitive detection method. This analytical procedure has the capability of detecting target analytes in the ng/L range, with recoveries above 80 %. The methodology was successfully applied to the analysis of testosterone and its photoproducts in several surface waters.
Показать больше [+] Меньше [-]A new strategy for determination of hydroxylamine and phenol in water and waste water samples using modified nanosensor Полный текст
2013
Sadeghi, Roya | Karimi-Maleh, Hassan | Khalilzadeh, Mohammad A. | Beitollahi, Hadi | Ranjbarha, Zahra | Zanousi, Mohammad Bagher Pasha
A carbon paste electrode modified with p-chloranil and carbon nanotubes was used for the sensitive and selective voltammetric determination of hydroxylamine (HX) and phenol (PL). The oxidation of HX at the modified electrode was investigated by cyclic voltammetry (CV), chronoamperommetry, and electrochemical impedance spectroscopy. The values of the catalytic rate constant (k), and diffusion coefficient (D) for HX were calculated. Square wave voltammetric peaks current of HX and PL increased linearly with their concentrations at the ranges of 0.1-172.0 and 5.0-512.0 μmol L(-1), respectively. The detection limits for HX and PL were 0.08 and 2.0 μmol L(-1), respectively. The separation of the anodic peak potentials of HX and PL reached to 0.65 V, using square wave voltammetry. The proposed sensor was successfully applied for the determination of HX and PL in water and wastewater samples.
Показать больше [+] Меньше [-]Sewage-exposed marine invertebrates: survival rates and microbiological accumulation Полный текст
2013
Stabili, Loredana | Terlizzi, Antonio | Cavallo, Rosa Anna
A large number of bacteria, including agents responsible for diseases, characterise sewage-polluted seawaters. Apart from standards for bathing waters and bivalve aquaculture waters, there are no general microbiological standards applicable to seawaters to help decide if bacterial pollution is within acceptable ranges. This study represents an attempt towards the issue of comparing the susceptibility of different marine invertebrates subjected to polluted seawater with a high microbial contamination. We explored the survival rates and the microbiological accumulation of mollusc bivalves, echinoderms and crustaceans species exposed to sewage-polluted seawaters. Microbiological analyses were performed on the polluted seawater and on the homogenates of exposed and unexposed specimens. Culturable bacteria (22 °C and 37 °C) and microbial pollution indicators (total coliforms, Escherichia coli and intestinal enterococci) were measured. When exposed to the sewage-polluted seawater, the examined invertebrates showed different survival rates. In the filter feeders, bacterial densities at 22 °C and 37 °C rose after 96 h of exposure to sewage. The highest concentrations of total coliforms and intestinal enterococci were found in exposed bivalve Mytilus galloprovincialis. The concentrations of bacteria growing at 37 °C were lower in the exposed deposit feeders compared to the polluted seawater. Some yeasts were absent in several exposed species although these yeasts were present in the polluted seawater. Our data suggest that the examined filter feeders, given their capability to survive and accumulate bacteria, may counteract the effects of sewage and restore seawater quality.
Показать больше [+] Меньше [-]Modelling the adsorption of mercury onto natural and aluminium pillared clays Полный текст
2013
Eloussaief, Mabrouk | Sdiri, Ali | Benzina, Mourad
INTRODUCTION: The removal of heavy metals by natural adsorbent has become one of the most attractive solutions for environmental remediation. Natural clay collected from the Late Cretaceous Aleg formation, Tunisia was used as a natural adsorbent for the removal of Hg(II) in aqueous system. METHODS: Physicochemical characterization of the adsorbent was carried out with the aid of various techniques, including chemical analysis, X-ray diffraction, Fourier transform infrared and scanning electron micrograph. Batch sorption technique was selected as an appropriate technique in the current study. Method parameters, including pH, temperature, initial metal concentration and contact time, were varied in order to quantitatively evaluate their effects on Hg(II) adsorption onto the original and pillared clay samples. Adsorption kinetic was studied by fitting the experimental results to the pseudo-first-order and pseudo-second-order kinetic models. The adsorption data were also simulated with Langmuir, Freundlich and Temkin isotherms. RESULTS: Results showed that the natural clay samples are mainly composed of silica, alumina, iron, calcium and magnesium oxides. The sorbents are mainly mesoporous materials with specific surface area of <250 m² g⁻¹. From the adsorption of Hg(II) studies, experimental data demonstrated a high degree of fitness to the pseudo-second-order kinetics with an equilibration time of 240 min. The equilibrium data showed the best model fit to Langmuir model with the maximum adsorption capacities of 9.70 and 49.75 mg g⁻¹ for the original and aluminium pillared clays, respectively. The maximum adsorption of Hg(II) on the aluminium pillared clay was observed to occur at pH 3.2. The calculated thermodynamic parameters (∆G°, ∆H° and ∆S°) showed an exothermic adsorption process. The entropy values varied between 60.77 and 117.59 J mol⁻¹ K⁻¹, and those of enthalpy ranged from 16.31 to 30.77 kJ mol⁻¹. The equilibrium parameter (R L) indicated that the adsorption of Hg(II) on Tunisian smectitic clays was favourable under the experimental conditions of this study. CONCLUSION: The clay of the Aleg formation, Tunisia was found to be an efficient adsorbent for Hg(II) removal in aqueous systems.
Показать больше [+] Меньше [-]Effect of ethylenediamine-N,N′-disuccinic acid on Fenton and photo-Fenton processes using goethite as an iron source: optimization of parameters for bisphenol A degradation Полный текст
2013
Huang, Wenyu | Brigante, Marcello | Wu, Feng | Hanna, Khalil | Mailhot, Gilles
The main disadvantage of using iron mineral in Fenton-like reactions is that the decomposition rate of organic contaminants is slower than in classic Fenton reaction using ferrous ions at acidic pH. In order to overcome these drawbacks of the Fenton process, chelating agents have been used in the investigation of Fenton heterogeneous reaction with some Fe-bearing minerals. In this work, the effect of new iron complexing agent, ethylenediamine-N,N'-disuccinic acid (EDDS), on heterogeneous Fenton and photo-Fenton system using goethite as an iron source was tested at circumneutral pH. Batch experiments including adsorption of EDDS and bisphenol A (BPA) on goethite, H₂O₂ decomposition, dissolved iron measurement, and BPA degradation were conducted. The effects of pH, H₂O₂ concentration, EDDS concentration, and goethite dose were studied, and the production of hydroxyl radical (•OH) was detected. The addition of EDDS inhibited the heterogeneous Fenton degradation of BPA but also the formation of •OH. The presence of EDDS decreases the reactivity of goethite toward H₂O₂ because EDDS adsorbs strongly onto the goethite surface and alters catalytic sites. However, the addition of EDDS can improve the heterogeneous photo-Fenton degradation of BPA through the propagation into homogeneous reaction and formation of photochemically efficient Fe-EDDS complex. The overall effect of EDDS is dependent on the H₂O₂ and EDDS concentrations and pH value. The high performance observed at pH 6.2 could be explained by the ability of O ₂ •⁻ to generate Fe(II) species from Fe(III) reduction. Low concentrations of H₂O₂ (0.1 mM) and EDDS (0.1 mM) were required as optimal conditions for complete BPA removal. These findings regarding the capability of EDDS/goethite system to promote heterogeneous photo-Fenton oxidation have important practical implications for water treatment technologies.
Показать больше [+] Меньше [-]Studies on the bacteriological qualities of the Buffalo River and three source water dams along its course in the Eastern Cape Province of South Africa Полный текст
2013
Chigor, Vincent N. | Sibanda, Timothy | Okoh, Anthony I.
The Buffalo River and its dams are major surface water sources used for fresh produce irrigation, raw water abstraction and recreation in parts of the Eastern Cape Province in South Africa. Over a 12-month period (August 2010 to July 2011), we assessed the bacteriological qualities of water from the river and 3 source water dams along its course. Faecal indicator bacteria (FIB), including total coliform (TC), faecal coliform (FC) and enterococci (ENT) counts, were high and ranged as follows: 1.9 × 10²–3.8 × 10⁷, 0–3.0 × 10⁵ and 0–5.3 × 10⁵ cfu/100 ml for TC, FC and ENT, respectively. Significantly (P < 0.05) higher concentrations of FC and ENT were observed at the sampling sites located at the lower reaches of the river compared to the upper reaches, and at Bridle Drift Dam compared to the other two dams. FIB counts mostly exceeded the recommended maximum values suggested by national and international guidelines for safe fresh produce irrigation, domestic applications, full-contact recreation and livestock watering. These results show that the bacteriological qualities of the Buffalo River and dams were poor, and suggest that sewage was dumped into the Buffalo River during the study period. Urban runoffs and effluents of wastewater treatment plants appear to be important sources of faecal contamination in the river. We conclude that these water bodies represent significant public health hazards. Provision of adequate sanitary infrastructure will help prevent source water contamination, and public health education aimed at improving personal, household and community hygiene is imperative.
Показать больше [+] Меньше [-]Effects of air pollution on lung function and symptoms of asthma, rhinitis and eczema in primary school children Полный текст
2013
Altuğ, Hicran | Gaga, Eftade O. | Döğeroğlu, Tuncay | Özden, Özlem | Örnektekin, Sermin | Brunekreef, B. | Meliefste, Kees | Hoek, Gerard | Van Doorn, Wim
Health effects of ambient air pollution were studied in three groups of schoolchildren living in areas (suburban, urban and urban-traffic) with different air pollution levels in Eskişehir, Turkey. This study involved 1,880 students aged between 9 and 13 years from 16 public primary schools. This two-season study was conducted from January 2008 through March 2009. Symptoms of asthma, rhinitis and eczema were determined by the International Study of Asthma and Allergies in Childhood questionnaire in 2008. Two lung function tests were performed by each child for summer and winter seasons with simultaneous ambient air measurements of ozone (O3), nitrogen dioxide (NO2) and sulfur dioxide (SO2) by passive sampling. Effects of air pollution on impaired lung function and symptoms in schoolchildren were estimated by multivariate logistic regression analyses. Girls with impaired lung function (only for the summer season evaluation) were more observed in suburban and urban areas when compared to urban-traffic area ([odds ratio (OR) = 1.49; 95 % confidence interval (CI) 1.04-2.14] and [OR = 1.69 (95 % CI 1.06-2.71)] for suburban vs. urban-traffic and urban vs. urban-traffic, respectively). Significant association between ambient ozone concentrations and impaired lung function (for an increase of 10 μg m(-3)) was found only for girls for the summer season evaluation [OR = 1.11 (95 % CI 1.03-1.19)]. No association was found for boys and for the winter season evaluation. No association was found between any of the measured air pollutants and symptoms of current wheeze, current rhinoconjunctivitis and current itchy rash. The results of this study showed that increasing ozone concentrations may cause a sub-acute impairment in lung function of school aged children.
Показать больше [+] Меньше [-]Biodegradation and removal of 3,4-dichloroaniline by Chlorella pyrenoidosa based on liquid chromatography-electrospray ionization-mass spectrometry Полный текст
2013
Wang, Shujuan | Poon, Karen | Cai, Zongwei
3,4-Dichloroaniline (3,4-DCA), widely used in the synthesis of dyes, textile and herbicides, is toxic to living organisms. The purpose of this study was to investigate the capability of green algae in degrading and removing 3,4-DCA in water. An environmentally ubiquitous green alga Chlorella pyrenoidosa was isolated from fresh aquatic environment. Then unicellular alga was incubated with 3,4-DCA at a concentration of 4.6 μg/ mL in water. The residual concentration of 3,4-DCA in the medium and the metabolites were analyzed. A removal percentage of 78.4 % was obtained over a 7-day period. Two major metabolites with less toxicity were identified as 3,4-dichloroformanilide and 3,4-dichloroacetanilide from the liquid chromatography-electrospray ionization-mass spectrometry analysis. The application of microalga C. pyrenoidosa may have potential for removing the environmental pollutant in aquatic environment.
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