Composition and origin of PM2.5 in Mediterranean Countryside.

In this work PM2.5 was collected during winter and summer in a Sardinian village (Gonnostramatza, Italy) highly affected by biomass burning emissions. A multi-technique approach was adopted for the complete PM chemical characterization. The bulk characterization was performed by IC (Ion Chromatography), HPAEC (High-Performance Anion-Exchange Chromatography), TOT (Thermal Optical Transmittance) and ED-XRF (Energy-Dispersive X-Ray Fluorescence) while XPS (X-ray Photoelectron Spectroscopy) was used for the surface characterization. Using levoglucosan as specific tracer of biomass burning emissions, the assessment of the impact of this source was carried out and it represent the major PM source at the investigate site during winter. In winter the average levoglucosan concentration is 2096 ±â€¯324 ng/m3 while during summer its concentration is negligible (18 ±â€¯7 ng/m3). Levoglucosan content in PM2.5 during winter is on average 13.7%; it is estimated that 65% of PM2.5 is due to wood burning. XPS has been exploited in this work aiming at highlighting possible differences between surface and bulk composition of PM2.5. The surface of the particulate matter resulted enriched in carbon compared to the bulk. Among the components of XPS C1s signals recorded on the samples collected during winter, it was found that the signal at 286.5 eV, which is due to the presence of COH, reflects the bulk composition of levoglucosan.

An XPS analytical approach for elucidating the microbially mediated enargite oxidative dissolution.

In this work, the microbe-mediated oxidative dissolution of enargite surfaces (Cu(3)AsS(4)) was studied on powdered samples exposed to 9K nutrient solution (pH 2.3) inoculated by Acidithiobacillus ferrooxidans initially adapted to arsenopyrite. These conditions simulate the acid mine environment. The redox potential of the inoculated solutions increased up to +0.72 V vs normal hydrogen electrode (NHE), indicating the increase of the Fe(3+) to Fe(2+) ratio, and correspondingly the pH decreased to values as low as 1.9. In the sterile 9K control, the redox potential and pH remained constant at +0.52 V NHE and 2.34, respectively. Solution analyses showed that in inoculated medium Cu and As dissolved stoichiometrically with a dissolution rate of about three to five times higher compared to the sterile control. For the first time, X-ray photoelectron spectroscopy (XPS) was carried out on the bioleached enargite powder with the aim of clarifying the role of the microorganisms in the dissolution process. XPS results provide evidence of the formation of a thin oxidized layer on the mineral surface. Nitrogen was also detected on the bioleached surfaces and was attributed to the presence of an extracellular polymer substance layer supporting a mechanism of bacteria attachment via the formation of a biofilm a few nanometers thick, commonly known as nanobiofilm.

Structural characterization of complexes between iminodiacetate blocked on styrene-divinylbenzene matrix (Chelex 100 resin) and Fe(III), Cr(III), and Zn(II) in solid phase by energy-dispersive X-ray diffraction.

Local structure of Fe(III), Cr(III), and Zn(II) cations has been determined on the amorphous sample by means of the difference method used for liquid systems. We recorded energy-dispersive X-ray diffraction spectra of a chelating resin (Chelex 100), containing paired iminodiacetate ions coupled to a styrene-divinylbenzene support, in several ionic forms. Coordination geometry of Fe(III), Cr(III), and Zn(II) metal cations with Chelex 100 resin ligand sites, and conformation of the ligand groups have been determined.

X-ray photoelectron spectra of Pd(II) and Pt(II) complexes with 1,3-thiazolidine-2-thione. A quantum mechanics study on the free ligand.

Metal complexes of general formula M(ttz)2X2 (with M= Pd(II) or Pt(II); X = Cl or Br; ttz = 1,3-thiazolidine-2-thione) have been synthetized as crystalline compounds and studied by means of X-ray Photoelectron Spectroscopy (XPS). The chemical shift of core level signals showed that ttz is bonded to the metal through the thioketonic sulphur atom and that electronic charge redistribution in the ligand takes place after complexation. No metal-nitrogen bonds are present. This is consistent with the results of all the quantum mechanical models according to which hydrogen is bound to nitrogen, even in the hydrogen bonded complex, making the latter rather unavailable to coordination

Synthesis and characterization of a cobalt(III) complex with 1-(D-3-mercapto-2-methylpropionyl)-L-proline.

The reaction of CoCl2 with 1-(D-3-mercapto-2-methylpropionyl)-L-proline (L or captopril) yields a new nanocrystalline complex with general formula [CoL2(OH)]2. The complex has been characterised with infrared (IR) and ultra-violet visible (UV-vis) spectroscopies, magnetic measurements, X-ray photoelectron spectroscopy (XPS), and wide angle X-ray scattering (WAXS). XPS analyses is a valuable tool for studying the chemical composition and the chemical state of elements at the surface of solids whereas WAXS provides information on the short range order. A model is proposed for the binding of the complex and its structure: the Co(III) ion is bonded with a pseudo-octahedral configuration. Captopril molecules are coordinated via mercapto group and amidic C=O group to Co(III) ions: two S atoms are bridging bonded between two Co(III) ions. The OH- ion completes the coordination around the Co(III).

X-ray photoelectron spectra of complexes with 1-(D-3-mercapto-2-methylpropionyl)-L-proline and Ni(II), Cd(II) and Cu(I): synthesis and LAXS study of Cu(I) derivative.

Metal complexes of general formula Na2M(CAP)2xH2O (with M = Cd(II) or Ni(II), x = 7 and 4, respectively, CAP = 1-(D-3-mercapto-2-methylpropionyl)-L-proline) and NaCuCAPx3H2O have been synthesized as amorphous compounds and studied by means of X-ray photoelectron spectroscopy (XPS). Cu(I) derivative has been studied by IR, XPS and large-angle X-ray scattering (LAXS). IR data and the chemical shift of core level signals suggest that CAP is bonded to the metal via the sulphur atom and the carbonylic oxygen. LAXS data confirm this finding and are consistent with a tetrahedral configuration around the copper ion. The CAP molecule is bonded through the sulphur and the carbonylic oxygen and two water molecules complete the coordination around the metal. The sodium ion exhibits a tetrahedral configuration and interacts with the carboxylic group and two water molecules. One of these is bridging bonded between copper and sodium. No metal-nitrogen bonds are present.