Search results for "Chlorin"
showing 10 items of 374 documents
Pd-catalyzed hydrodehalogenation of chlorinated olefins: Theoretical insights to the reaction mechanism
2012
Abstract Density functional theory calculations are applied to study energetics of trichloroethene (TCE) hydrodechlorination over pure Pd(1 1 1), chlorine-covered Pd(1 1 1), and Pd island supported by Au(1 1 1). Our results show that in all cases C Cl bond breakings take place more readily than C H bond formations and that TCE dechlorinates fully producing CCH precursors for the hydrogenations. The reaction pathway through radical-like species provides a possible explanation to the experimental product distributions that show a nominal amount of lesser chlorinated species in the presence of excess hydrogen. The surface chlorine resulted from the TCE decomposition weakens the binding of the …
Investigation of electrode material – redox couple systems for reverse electrodialysis processes. Part II: Experiments in a stack with 10–50 cell pai…
2013
Abstract The performances of reverse electrodialysis depend on several factors, including the nature of the electrode material and of the redox processes adopted to make possible the conversion between chemical potential and electric power. In this paper the possible utilization of various redox processes (reduction/oxidation of iron species, oxidation and reduction of water, oxidation of chlorine and reduction of water) was studied in a stack equipped with 10–50 cell pairs and by focused electrolyses in a three compartment cell. The effect of selected redox processes on power density output and eventual contamination of saline solutions flowing in the stack was evaluated in detail. The eff…
Evaluation of a solid-phase extraction system for determining pesticide residues in milk.
1993
Abstract A simple and rapid procedure based on reversed solid-phase extraction with octadecylsilica was developed for determining chlorinated pesticide residues in milk. The need for an agent that breaks the fat globules was first investigated and the method variables were optimized on whole homogenized milk (3.6% fat content). Recovery experiments performed for 26 organochlorine pesticides at levels of 3–40 μg/l gave > 80% recoveries for all the compounds. The method was validated and evaluated by comparison with two widely used liquid-liquid extraction methods. The performance was checked by analysis of a certified standard with natural low endogenous levels (CMR 187) and different kinds …
Aroclor 1254 inhibits the chemiluminescence response of peritoneal cavity cells from sharpsnout sea bream (Diplodus puntazzo)
2014
Chronic exposure to polychlorinated biphenyls (PCBs) affect the immune system of fish and could lead to a decreased disease resistance. The effects of Aroclor 1254, PCB mixtures, on the Diplodus puntazzo innate immunity were examined by assaying the zymosan stimulated chemiluminescence response (CL) of peritoneal cavity cells (PCCs) at various times (1, 24, 48 h and 1-4 weeks) from intraperitoneal injection of the xenobiotic (1 mg kg(-1) body weight). Controls were performed by assaying cells from medium-treated fish. Since the kinetic of the chemiluminescence response showed the highest peak at 25 min after the zymosan stimulation of the cells, the values found at that time were considered…
Concentration of retene and resin acids in sedimenting particles collected from a bleached kraft mill effluent receiving lake
2000
Abstract The concentration of retene, a di-alkyl substituted PAH derived microbially and thermally from dehydroabietic acid, eight resin acids and their derivatives were analysed from sedimenting particles collected from five lake sites receiving pulp and paper mill effluents and from two reference sites. At five of the sites, samples were collected prior and after a conventional aerated lagoon wastewater treatment system of the mill was modernized with an activated sludge plant, and elemental chlorine free bleaching (ECF) had replaced chlorine bleaching. The highest level of retene was 30.0–53.8 μ g/g dry weight (d.w.), observed 3 km downstream from the mill. Nine kilometers downstream fr…
Photochemical sample treatment for extracts clean up in PCB analysis from sediments.
2013
Sample purification can be considered the most polluting step of the whole analytical process for PCBs determination in sediment samples. The use of photochemical sample treatment represents an alternative methodology for extracts clean up allowing for a reduction of the used amount of organic solvents. The first application of a photochemical sample treatment for the selective removal or reduction of organic substances interfering with PCBs analyses in sediments is reported. The method's efficiency and robustness were compared with currently used chromatographic purification. Quality parameters such as recovery, linearity and reproducibility were studied. The entire procedure was validated…
Long-term characterization of trihalomethane levels in drinking water
2010
Water chlorination leads to the formation of trihalomethanes (THM). In this case study, the levels of THM during the chlorination process of the drinking water in Valencia (Spain) were determined over a 12-year period. Different control areas and points were strategically sampled and samples were analyzed by gas chromatography. Temporal tendencies, as well as spatial and seasonal variations, were established. The individual distribution of THM was also evaluated. Factors such as distances from chlorination points and inter-month seasonal distribution, including ambient temperature effect, were assessed. The range of total THM concentrations measured in the water network goes from 4 to 184 µ…
Alteration of serotonin system by polychlorinated biphenyls exposure.
2011
Although commercial production of polychlorinated biphenyls (PCBs) was banned in 1979, PCBs continue to be an environmental and health concern due to their high bioaccumulation and slow degradation rates. In fact, PCBs are still present in our food supply (fish, meat, and dairy products). In laboratory animals, exposure to single PCB congener or to mixtures of different congeners induces a variety of physiological alterations. PCBs cross the placenta and even exposure at low level is harmful for the foetus by leading to neurodevelopment alterations. Serotonin system which regulates many physiological functions from platelet activation to high cerebral processes and neurodevelopment is one o…
Persistent Organic Pollutants and Fatty Acid Profile in a Typical Cheese from Extensive Farms: First Assessment of Human Exposure by Dietary Intake
2022
Dairy products represent an important source of beneficial substances for humans. At the same time, they can expose the consumers to environmental contaminants ingested by animals through their diet, influencing their health negatively. This experiment aims to evaluate the risk and benefits related to the consumption of typical stretched cheeses, considering their fatty acid (FA) profile and persistent organic pollutants (POPs) content. Six representative farms, two of them organic, raising Cinisara cattle were selected, considering the typical extensive management systems, based on feeding of natural pasture integrated with concentrate and hay depending on the availability of forage on pas…
Mixed Function Oxidase Activity and Organochlorine Levels in Farmed Sharpsnout Seabream (Diplodus puntazzo) from Two Intensive Aquaculture Facilities
2004
Mixed function oxidase (MFO) activities and organochlorine levels were investigated in liver of farmed sharpsnout seabream bred in two intensive facilities, a sea farm and a land-based farm. The aim of this study is to investigate how different facility locations and breeding conditions might affect fish metabolic capabilities and accumulation of toxic chemicals in farmed sharpsnout seabream. The differences between breeding two or more fish species in the same cage or tank known as polyculture, and monoculture (1 species) were also investigated. The results showed that both facility location (sea and land) as well as breeding systems (polyculture and monoculture) might be responsible for t…