Search results for " Metals"

ASSESSMENT OF HEAVY METAL CONTAMINATION IN TERRACES FOR PUBLIC USE RECOVERED IN THE CITY OF PALERMO AND IN AGRICULTURAL TERRACES

2017

The contamination by heavy metals in the soil is nowadays considered an indicator of environmental pollution caused by to several factors, such as waste disposal, industrial discharges and the use of irrigation water. Developed in collaboration with SO.GEST Ambiente Laboratory, in Palermo, this study had as a purpose to monitor the levels of heavy metals - Cd, Cr, Fe, Mn, Pb, Zn -both in public lands and in agricultural terrains. All the soil samples collected have been subjected to an acid extraction process by using HCL and eventually to a mass spectrometer-based analysis for the quantitative/ qualitative determination, specifically by the technique of flame atomic absorption spectrophoto…

Photoelectrochemical Synthesis of Polypyrrole on Anodic Ta2O5 Films

2007

Polypyrrole film was photoelectrochemically grown on insulating Ta2O5 anodic film in acetonitrile solution. A characterization by photocurrent spectroscopy PCS of metal/oxide/polypyrrole interface was carried out. The PCS results suggest that a metallic-like PPy is formed under illumination at constant anodic potential. By polarizing the polypyrrole at cathodic potentials a photocurrent spectrum typical of p-type semiconducting film was recorded. A scanning electron microscopy study of PPy surfaces solution side and oxide side allowed us to obtain information on the morphology of the polymer as well as a rough estimate of the film thickness and of the diameter of PPy globules at the two int…

Photoelectrochemical evidence of inhomogeneous composition at nm length scale of anodic films on valve metals alloys

2015

Anodic films of different thickness (∼30 nm and 70 nm) were grown by anodizing sputtering-deposited Ta-19at% Al to different formation voltages. N incorporation into the anodic films was inducing by performing the anodizing process in ammonium containing solutions. Layered anodic films were prepared by a double formation procedure with a first anodizing step in ammonium biborate solution and second anodizing step in borate buffer solution, or vice versa. Glow Discharge Optical Emission Spectroscopy was employed to show the distribution of N across the oxide. Photoelectrochemical measurements evidenced a red shift of the light absorption threshold due to N incorporation. A model was proposed…

NiO@Ni core shell for electrochemical detection of Hg ions

2018

Heavy metals are considered as one of the most dangerous chemicals for human health. Among heavy metals, mercury is one of the most dangerous one: few ppb of Hg can cause serious damages to brain, heart, lungs and kidney. The Environmental Protection Agency setted the maximum concentration of Hg in water as 2 ppb [1] . Nowadays is very important to develop new and novel sensors for heavy metals that could be cheap, easy to use and for in-situ and real-time analysis and in this context electrochemical sensors are perfect candidates [2] . The more powerful electrochemical tequinique is Square Wave Anodic Strippic Voltammetry (SWASV), a two step techinique were the heavy metals are first depos…

Diffusion Dialysis for Separation of Hydrochloric Acid, Iron and Zinc Ions from Highly Concentrated Pickling Solutions

2020

Acid recovery from pickling waste solutions is an important step to enhance hot-dip-galvanizing industry process sustainability. Diffusion dialysis (DD) can be used to separate acids and heavy metals (e.g., iron and zinc) from pickling waters, promoting the circular use of such raw materials. In the present study, a laboratory scale unit operating in batch and a continuous large scale unit, both equipped with Fumasep anionic exchange membranes, were tested. Results obtained show that zinc and iron concentration affect the HCl recovery in opposite ways. Iron chlorides enhance acid recovery, while zinc chlorides considerably tend to diffuse through the membrane because of negatively charged c…

The organic carbon derived from sewage sludge as a key parameter determining the fate of trace metals.

2007

8 pages; International audience; In a sandy agricultural soil of south-west of France, continuously cultivated with maize and amended with sewage-sludge over 20 years, the behavior of three trace metals (Cu, Pb, and Zn) was studied during the sludge applications (1974-1993) and after its cessation (1993-1998). Using the delta13C analysis, the dynamics of different sources of organic matter were followed in order to elucidate the influence of the sludge-derived organic matter on the fate of trace metals in the soil and its particle size fractions. This study revealed that sludge-derived organic matter contributed to the formation of macroaggregates through the binding of preexisting microagg…

Sampling procedure in a willow plantation for chemical elements important for biomass combustion quality

2015

Willow (Salix spp.) is expected to contribute significantly to the woody bioenergy system in the future, so more information on how to sample the quality of the willow biomass is needed. The objectives of this study were to investigate the spatial variation of elements within shoots of a willow clone ‘Tordis’, and to reveal the relationship between sampling position, shoot diameters, and distribution of elements. Five Tordis willow shoots were cut into 10–50 cm sections from base to top. The ash content and concentration of twelve elements (Al, Ca, Cd, Cu, Fe, K, Mg, Mn, Na, P, Si, and Zn) in each section were determined. The results showed large spatial variation in the distribution of mos…

Environmental reconstruction of Trapani saltmarsh (southwestern Sicily) during the last 80 years. An integrated approach by using benthic foraminifer…

2013

Reactivity of antitumor coinage metal-based N-heterocyclic carbene complexes with cysteine and selenocysteine protein sites

2021

Abstract The reaction of the antitumor M(I)-bis-N-heterocyclic carbene (M(I)-NHC) complexes, M = Cu, Ag, and Au, with their potential protein binding sites, i.e. cysteine and selenocysteine, was investigated by means of density functional theory approaches. Capped cysteine and selenocysteine were employed to better model the corresponding residues environment within peptide structures. By assuming the neutral or deprotonated form of the side chains of these amino acids and by considering the possible assistance of an external proton donor such as an adjacent acidic residue or the acidic component of the surrounding buffer environment, we devised five possible routes leading to the binding o…

Mechanisms for Translocation of Heavy Metals from Soil to Epigeal Mosses

2011

The mechanisms for translocation of heavy metals from soil to epigeal mosses were investigated. The first mechanism was demonstrated for (137)Cs and involved the uplifting of the pollutant-containing dust from the soil, followed by the local secondary deposition on surfaces of epigeal mosses and epiphytic lichens. The second mechanism involved the diffusion of metal cations from the soil through water wetting the moss into the gametophyte. The mechanism was demonstrated by measuring the electric conductance of wetted gametophytes with single ends immersed in solutions of Cu and Na salts. In addition, the concentrations of Cu and Cd were compared in moss samples exposed to the natural soil a…