Search results for " Metals"
showing 10 items of 462 documents
Improvement of the photo-stability of polystyrene-block-polybutadiene-block-polystyrene through carbon nanotubes
2015
Abstract The photo-stability of Polystyrene-Polybutadiene-Polystyrene (SBS) based nanocomposites containing bare multi-walled carbon nanotubes (CNTs) and carbon nanotubes bearing carboxylic functional groups (CNTs-COOH) in comparison to that of pristine SBS has been studied. The photo-oxidation of pristine SBS occurs through crosslinking reactions and oxidized species formation and both these processes begin at early stage of exposure. The formation of crosslinking, formerly in polybutadiene phase, assessed by spectroscopical (FTIR), mechanical, dynamic mechanical and rheological analysis, leads to occurrence of internal mechanical stresses in the solid state and the SBS samples become prem…
Biochar from byproduct to high value added material – A new adsorbent for toxic metal ions removal from aqueous solutions
2018
Abstract An activated biochar coming from pyrolysis of dead Posidonia oceanica residues has been tested as adsorbent material for Cd2+, Pb2+ and Cu2+ ions. The biomass, the activated and the non activated biochars were previously characterized by using several instrumental techniques. The pH of metal ion solution in kinetic and thermodynamic adsorption experiments was fixed at 5 whilst, the dependence on ionic medium, ionic strength and temperature have been evaluated carrying out batch experiments at different experimental conditions. Differential Pulse Anodic Stripping Voltammetry and Inductively Coupled Plasma Optical Emission Spectroscopy have been used to measure the metal ion concentr…
2019
Energy-level alignment at organic-metal interfaces plays a crucial role for the performance of organic electronic devices. However, reliable models to predict energetics at strongly coupled interfaces are still lacking. We elucidate contact formation of 1,2,5,6,9,10-coronenehexone (COHON) to the (1 1 1)-surfaces of coinage metals by means of ultraviolet photoelectron spectroscopy, x-ray photoelectron spectroscopy, the x-ray standing wave technique, and density functional theory calculations. While for low COHON thicknesses, the work-functions of the systems vary considerably, for thicker organic films Fermi-level pinning leads to identical work functions of 5.2 eV for all COHON-covered meta…
Metallophilicity-assisted assembly of phosphine-based cage molecules.
2014
A family of supramolecular cage molecules has been obtained via self-assembly of the phosphine-gold coordination complexes following an aurophilicity-driven aggregation approach. Use of the di- (PP) or tridentate (PPP) phosphine ligands Pn (n = 2, 3) with rigid polyaromatic backbones leads to clean formation of the coordination Pn(Au(tht))n(n+) species, sequential treatment of which with H2O/NEt3 and excess of H2NBu(t) gives the finite 3D structures of two major types. The cylindrical-like hexametallic cages [(PPAu2)3(μ3-NBu(t))2](2+) are based on the diphosphines PP = 1,4-bis(diphenylphosphino)benzene (1), 4,4'-bis(diphenylphosphino)biphenyl (2), 4,4"-bis(diphenylphosphino)terphenyl (3), w…
Site Preference in Multimetallic Nanoclusters: Incorporation of Alkali Metal Ions or Copper Atoms into the Alkynyl-Protected Body-Centered Cubic Clus…
2016
The synthesis, structure, substitution chemistry, and optical properties of the gold-centered cubic monocationic cluster [Au@Ag8@Au6(C≡CtBu)12]+ are reported. The metal framework of this cluster can be described as a fragment of a body-centered cubic (bcc) lattice with the silver and gold atoms occupying the vertices and the body center of the cube, respectively. The incorporation of alkali metal atoms gave rise to [MnAg8−nAu7(C≡CtBu)12]+ clusters (n=1 for M=Na, K, Rb, Cs and n=2 for M=K, Rb), with the alkali metal ion(s) presumably occupying the vertex site(s), whereas the incorporation of copper atoms produced [CunAg8Au7−n(C≡CtBu)12]+ clusters (n=1–6), with the Cu atom(s) presumably occup…
On the Interaction of Carbon Nanowires with Noble Metals through a Study of Their Surface-Enhanced Raman Spectra
2008
This paper deals with the interaction of linear carbon chains (polyynes) with silver and gold surfaces in the form of nanometer-sized clusters. Surface-enhanced Raman signals have been detected rev...
Effect of transition metals and homogeneous hydrogen producers in the hydrothermal liquefaction of sewage sludge
2022
Hydrothermal liquefaction (HTL) of sewage sludge (SS) was performed in the presence of metallic Zn, Fe and Ni to investigate their effect on the performances of the process in terms of product yields and quality. Experiments were performed in subcritical water at 350 ◦C for 10 min using each metal individually and in the presence of homogenous hydrogen producers like formic acid (FA) and KOH. Interesting results were obtained with Zn that when used alone or in the presence of KOH, increased the cumulative biocrude (BC) yields and resulted in energy recoveries (ER) higher than 100% with respect to initial energy content of the biomass, thus indicating that HTL of SS is globally endothermic. …
Influence of Temperature on Characteristics of Particulate Matter and Ecological Risk Assessment of Heavy Metals during Sewage Sludge Pyrolysis
2021
The formation process of Particulate Matter (PM) during sludge pyrolysis at different temperatures (300–700 °C) and the ecological risks of heavy metals were studied. The results showed that the particulate matter is mainly condensed on the quartz film in a carbon-based organic matter when the pyrolysis temperature was between 200–500 °C in a volatilization process. Inorganic particles was found in the particulate matter when the temperature was raised to 500–700 °C in a decomposition stage. Heavy metals were enriched in particulate matter with increase in pyrolysis temperature. When the temperature reached 700 °C, the concentration of Pb and Cd in the particulate matter significantly incre…
Effect of Plasma Treatment on Mechanical and Thermal Properties of Marble Powder/Epoxy Composites
2016
The aim of this work was to study the effect of the plasma treatment on the behavior of composite structures reinforced with marble powder, obtained as processing waste in the “Custonaci” basin. Moreover, different filler amounts (i.e. 10%wt, 20%, 30% in weight) were investigated. For the mechanical characterization, tensile and flexural quasi-static tests, Charpy impact test, and dynamic mechanical thermal analysis (DMTA) were performed. For the thermal stability, thermogravimetric analysis was carried out. Finally, real density and fraction of voids were measured. It was observed that untreated marble powder, on one hand, increases tensile and flexural stiffness and improves thermal stabi…
Geochemical comparison of natural and anthropogenic metal fluxes in extreme environments: Mt. Etna volcano (Italy) and Šalek Valley (Slovenia)
2009
Geochemical comparison between some metals (As, Cd, Cu, Pb, Se, V, Zn) emissions from an active volcano (Mt. Etna) and a highly industrialized area (Šalek Valley) showed some interesting similarities: in general, most of the elements emitted into the atmosphere do not return to the Earth’s surface and are therefore dispersed into the environment. Exceptions for Šalek Valley are Cd, which probably derives in large part from rock leaching, and in part As and Pb, which fall mostly as ash. Also, Etna’s emissions are richer in Cd and Cu, whereas industrial emissions at Šalek Valley are richer in V and Zn. All other metals have similar fluxes in the two types of emissions.