Showing papers by "Nicola Senesi published in 1998"

Structure and surface reactions of soil particles.

Abstract: Partial table of contents: MINERALS-ORGANICS-MICROORGANISMS INTERACTIONS AND CHARACTERIZATION OF SOIL PARTICLES. From Particles to Architecture: Fractals, Aggregation and Scaling in Soil Science (J. Crawford & B. Sleeman). Fractal Principles and Methods Applied to the Chemistry of Sorption onto Environmental Particles (I. Okuda & N. Senesi). ADVANCED INSTRUMENTATION IN ANALYSIS OF SOIL PARTICLES. Electron Microscopy of Soil Components (Y. Chen). Applications of NMR Spectroscopy to the Study of the Chemistry of Environmental Interfaces (W. Earl & C. Johnston). Electron Spin Resonance Spectroscopy of Organic and Mineral Soil Particles (M. Cheshire & N. Senesi). REACTIONS AND PROCESSES AT THE SOIL PARTICLE-SOLUTION INTERFACE. Ion Adsorption at the Soil Particle-Solution Interface: Modeling and Mechanisms (S. Goldberg). Kinetics of Sorption/Release Reactions on Natural Particles (D. Sparks). Kinetics of Enzyme Reactions in Soil Environments (P. Nannipieri & L. Gianfreda). Index.

Thermal and Spectroscopic Characterization Of Composts From Municipal Solid Wastes

Abstract: Six composts from municipal solid wastes (MSW) were sampled after composting times of 3, 7, 15, 45, 60 and 350 days and analyzed by chemical analysis, fluorescence spectroscopy in emission, excitation and synchronous scan modes, Fourier transform infrared spectroscopy and differential scanning calorimetry, without carrying out any organic matter extraction. Thermal and spectroscopic techniques appeared to be powerful tools to investigate the evolution of MSW organic matter during composting, and provided evidence that the chemical transformations occurring in these heterogeneous materials yield products with molecular complexity and stability, similar to humic substances.

Characterization of Composts and Humic Acids from Pulp and Paper Mill Biosludges by DSC in Association with FT-IR Spectroscopy

Abstract: Samples of pulp and paper mill biosludges with different maturation ages (fresh biosludge and composts collected after 3 weeks, 1 year and 2 years of composting) and their corresponding humic acids were analyzed by thermal analysis with DSC in association with FT-IR spectroscopy. The DSC curves obtained exhibited endotherms in the low-temperature region, assigned to dehydration processes, exotherms at around 370°C, attributed to the loss of peptidic structures, and high-temperature exotherms, assigned to the loss of functional groups; the lignins were thermostable, regardless of the maturation age of the compost.

Electron paramagnetic resonance and ultraviolet-visible spectroscopic evidence for copper porphyrin in actinomycete melanins.

Abstract: The coordination chemistry of iron (III) (Fe3+) and copper (II) (Cu2+) in melanins synthesized by seven actinomycetes isolated from Brazilian latosol soils under savanna (cerrado) vegetation was investigated using electron paramagnetic resonance (EPR) and ultraviolet-visible (UV-Vis) spectroscopy. The EPR spectra indicated the presence of Cu2+ ions bound to oxygenated and nitrogenous functional groups, and rhombic coordinated Fe3+ ions. In some of the actinomycete melanins the EPR hyperfine splitting of Cu+2 ion complexes was well resolved, and indicated four magnetically equivalent nitrogen atoms in a plane. This result suggested the presence of Cu+2 porphyrin complexes, which was confirmed by Soret bands in the 400-nm region of the UV-Vis spectra. The concentration of Mn in actinomycete melanins, determined by inductively coupled plasma atomic emission spectroscopy, was lower than those of Cu and Fe.

Chemical and spectroscopic characterization of humic acids from a soil toposequence in Venezuela

Abstract: An investigation was conducted on physico‐chemical properties of humic acids (HAs) in Venezuelan soils. The HAs were extracted by the NaOH method from a Banco‐Bajio‐Estero soil toposequence (local names for soils located at high, intermediate and low topographic levels), in the Venezuelan plains (Mantecal, Apure State). The extracted HAs were analyzed for elemental composition and characterized by fluorescence, Fourier transform infrared (FT‐IR) and electron spin resonance (ESR) spectroscopies. The results showed that free radical concentration of HAs increased from soils at the highest to soils at the lowest topographic position. High carbon (C), nitrogen (N), and carboxyl group contents, E4/E6 ratio, aliphatic character and concentration of free radicals, and low oxygen (O) and phenolic hydroxyl group contents and total acidity were typical of HA from soils at the lower relief position. The FT‐IR spectra indicated that the HA from the soil at the lowest topographic position tended to have a sli...