147 research outputs found
The PAH composition in limpets (Patella vulgate L.) from the coasts of Sicily (Italy)
No full textThis article examines the presence, distribution, nature and sources of 19 Polycyclic Aromatic Hydrocarbons (PAH), in Patellae (patella vulgate L.) and seaweed (vulva) sampled in different stations of Sicilian coastal environments and analyzed for their polycyclic aromatic hydrocarbon (PAH) content. Analysis was performed by gas chromatography/mass spectrometry (GC/MS) with selected ion monitoring (SIM), after saponification of the sample and clean up of the extract. In the limpets the total concentration of polycyclic aromatic hydrocarbons ranged from 34 to 750 μg/Kg of dry matrix. The relative standard deviation (RSD) of the replicas on the concentrations of individual compounds ranged from 4 to 20%. The accuracy of method was estimated by analyzing "blank" samples spiked with known quantities of analytes and the recover percentage was 82 ± 12%. The detection limit (LOD) of analytical procedure was less than 0.2 μg/Kg d.w. for all analytes. The quantification limit (LOQ) of analytical procedure was less 0.7 μg/Kg d.w. The resulting distributions and weight ratios of specific compounds are discussed in terms of sampling location and origin. The results obtained show that levels of contamination vary from one sampling station to the next, while relative distributions of PAH is homogeneous in most stations. Lipidic content and total PAH concentrations were found not to be correlated and the compounds present in limpets were shown to be mainly of petrogenic origin. There is no evidence of coal-tar contamination. Copyright © 2006 Taylor & Francis Group, LLC
Leaves of nerium Oleander L. as bioaccunulators of polycyclic aromatic hydrocarbons (PAH) in the air of Palermo (Italy): extraction and GC-MS analysis, distribution and sources
No full textPolycyclic Aromatic Hydrocarbons (PAH) were determined in the leaves of Nerium oleander L. an evergreen plant that occurs widely in both urban and rural areas, to monitor the degree of pollution in the urban area of Palermo (Italy) compared to remote areas. Twenty sites (urban roadside, urban, urban park, suburban and rural) in and around Palermo city were investigated. The purpose of this research was to investigate concentration levels and distribution patterns and relate them to possible sources. Analysis of 19 PAH was performed by gas chromatography/mass spectrometry (GCMS) using selected ion monitoring (SIM). The total amount of PAH ranged from 10 to 166 μg/Kg d.w. Each source gives rise to a characteristic PAH pattern, and it is therefore possible to get access to the processes that generate the compounds. To this aim, the recommended as priority pollutants by the Environmental Protection Agency (EPA), perylene and three additional alkylated compounds were analyzed. Positive correlations were found between total PAH content of the leaves with CO, benzene and particulate levels measured in air of Palermo
EFFECT OF IONIC STRENGTH AND MEDIUM COMPOSITION ON THE REMOVAL OF Pb2+ BY ALGINATE GEL BEADS. DPVASV AND ICP-OES MEASUREMENTS.
No full textThe biosorption, i.e. a passive sequestering process by metabolically inactive biomass, shows a growing interest for toxic metal ions removal from contaminated aqueous solutions (1), such as municipal and industrial wastewaters. Since the sorption mechanism occurs mainly by ion exchange between the metal ion present in solution and the counter ion of the biopolymer (2), the efficiency of the sorption process largely depends on ionic strength and on the medium composition of solution containing the metal ion to be removed. In order to evaluate quantitatively the influence of ionic strength and medium on the metal removal process by the biomass, we
report here results of a study on the sorption capacity of calcium in gel phase toward Pb2+ in aqueous solution in different simple (NaCl, NaNO3) and mixed [NaCl+CaCl2, NaCl+MgCl2, NaCl+Na2SO4) ionic media, in a
wide range of ionic strength (0.05 < I/mol L
-1 < 0.8), and at room temperature. Investigations were performed by evaluating the Pb2+ concentration in the solution after adsorption onto different amounts of calcium alginate gel beads over continuous time. Measurements of Pb2+ concentration were carried out by Differential Pulse Anodic Stripping Voltammetry (DP-ASV) and by Inductively Coupled Plasma Optical Emission Spectroscopy ICP - OES. To avoid the hydrolysis of the of Pb2+ ion, the solution containing the metal ion to be removed was kept at pH ~ 5. The pseudo second-order model was used to fit sorption process kinetic data(3). Sorption equilibrium was analysed using Langmuir and Freundlich isotherm models. Although both isotherm equations fitted properly the equilibrium data, Langmuir model seems to fit data slightly better than the Freundlich model
Kinetic and equilibrium study for Pd(II) removal from aqueous solution by sorption onto calcium alginate gel beads
No full textThe more and more increasing use of catalytic converters to reduce the dangerous NOx and CO emission in the atmosphere by vehicle traffic produces a corresponding increase of palladium in the environment [1]. Among the so-called “platinum group Elements” (PGE), elemental palladium seems to be the most hazardous one because it can be easily and quickly oxidized to palladium(II) when put in contact with soil. The presence of palladium oxidized form is of great concern owing to its recognized toxicity towards plants, animals and humans. Therefore, as for the classical “heavy metals”, a removal of this element from the environment is needed and a subsequent recovery for its potential re-use is welcome [1].
Among the different techniques proposed for the removal and recovery of metal ions from aqueous solutions, the sorption by materials derived from biomass is one of the most promising [2]. The biomaterials for metal ions removal are available in large quantities, inexpensive and biodegradable and usually have high yields in terms of metal ion uptake [3]. The biosorption of palladium(II) and other precious metals on different kind of raw biomaterials has been extensively studied [4], but the direct use of the polyelectrolytes contained therein, which are the main responsible for their sorption capacity [5-6], was few investigated.
We report here results of a kinetic and thermodynamic study for palladium(II) removal from aqueous solutions by calcium alginate gel beads as sorbent biomaterial. The investigations were carried out in the pH range 2 to 5 at I = 0.01 mol L-1 (NaNO3 / NaCl) at different chloride concentration and at T = 25 °C. These experimental conditions were established on the basis of a speciation study on the Pd2+ - alginate system in aqueous solution, carried out to evaluate the strength of interaction between the metal ion and the alginate as sequestering agent.
A parallel study on the kinetics of calcium(II) release by gel beads was also carried out in order to have more information on the sorption mechanism.
Important similarities were found between the trends for the dependence on pH and chloride concentration of binding and sequestering ability (% PdAA species, pL0.5) and sorption (qe, qmax) parameters. In Figure is reported, as an example, the dependence of pL0.5 and qmax on CCl- at pH = 2 and at T = 25°C.
These similar trends show a close relation between the behaviour of alginate as sequestering agent in aqueous solution and calcium alginate gel beads as sorption material towards Pd2+ ion
Complexes of dioxouranium(VI) ion with glutamic and aspartic acids in NaCl aqueous solution
No full textAdsorption of polyciclic aromatic hydrocarbons (PAHs) by pine barks and their use for environmental pollution monitoring in the Palermo (ITALY) area
No full textAbsorption of polycyclic aromatic hydrocarbons by pinus bark: analytical method and use for environmental pollution monitoring in the Palermo area (Sicily, Italy)
No full textIn the light of using biomaterial as pollutants sorbents for the environmental biomonitoring, we report here the results of the absorption of polycyclic aromatic hydrocarbons (PAHs) by pine bark. Quantitative analysis of 19 different polycyclic aromatic compounds was performed, after Soxhlet extraction in dichloromethane, by means GC–MS technique. Pinus was chosen due to its wide distribution in the
Mediterranean area. The passive absorption of PAH by pine bark in the metropolitan areas allowed us to evaluate the air quality of Palermo. The obtained results showed a very high range of PAHs concentrations, from 33 mg/kg (bark dry weight), as SPAHs, at the control site to 1015 mg/kg along a road with high traffic flow
Sequestration of Pd2+ by polyamino-polycarboxylic ligands
No full textThe increase of the worldwide demand of “Platinum group elements” (PGE) for application in several fields such as industry, medicine, jewellery and, especially, in catalyst converter production, caused a noticeable increasing of PGE concentration in the
environment. Though palladium, among the anthropogenic PGE, is not the most abundant one, it is the most hazardous since it undergoes easily and quickly oxidation to palladium(II) when in contact with soils, with a consequent increase of its mobility in the environment. The presence of complexing agents, which form soluble complex species with palladium(II), favours the mobility of the ion with an increase of its availability to plants, animals and humans. Among anthropogenic complexing molecules, an important role is played by synthetic aminopolycarboxylic chelating agents (usually called with the acronym APC) whose concentration in the environment is progressively increasing owing to their considerable use in several fields (agriculture, industry, medicine) and a low biodegradability of most of them. The interaction of these ligands with palladium(II) ion leads to the formation of soluble complex species whose stability influences strongly the availability of palladium(II) in the environment. With the aim to assess the strength of interaction of Pd2+ with aminopolycarboxylic ligands, here we report the results of a systematic study, , on the formation of palladium(II) complex species with five APCs [ethylenediamine-N,N,N’,N’-tetraacetate (EDTA), (S,S)-Ethylenediamine-N,N′-disuccinic acid (S,S-EDDS), Nitrilotriacetate (NTA) and diethylenetriamine-N,N,N’,N’’,N’’-pentaacetate (DTPA) and triethylenetetraamine-N,N,N’,N’’,N’’’,N’’’-hexaacetate (TTHA)]. Owing to the high stability of the Pd2+ - APC complex species, the calculation of their stability constants
was very difficult and was possible only by combining the results obtained from two series of ISE-H+ potentiometric titration (in NaNO3 and in mixed NaNO3 /NaI ionic medium) and from ISE-H+ potentiometric /spectrophotometric titrations (in NaClO4). As expected, the stability of Pd-APC complex species is function of the number of carboxylic and amino groups present in the ligand molecules (e.g., logKPd(APC) = 37.00, 36.31, 23.60, 23.07 and 17.82 for TTHA, DTPA, EDTA, S,S-EDDS and NTA in Na+ ionic media, at I = 0.1 mol L-1 and T = 25°C). Results obtained on the stability of species in the Pd- S,S-EDDS show that this ligand, which is the most biodegradable APC ligand, can be used successfully as environmental friendly
chelating agent in substitution of the other less degradable APCs in all their application fields. From the stability data of the Pd2+ - APCs the sequestration capacity [expressed as pL50, i.e. the –log (APC concentration] necessary to bind the 50% of the metal ion) of the ligands under investigation towards palladium(II) ion was determined in the pH range considered. The pL50 is easily correlated to important physico-chemical parameters (pH, ionic strength, temperature, etc.) as shown in the Figure, were the dependence on pH of pL50 of the APCs towards Pd2+ ion is reported. As can be seen, TTHA and DTPA show almost the same sequestering ability in the pH range 2 – 10, clearly higher than that of EDTA, S,S-EDDS and NTA where a minor number
of amino and carboxylic groups is present in the molecule
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