Giuliana Ricca

Humic acids in the first generation of EUROSOILS

Humic acids (HAs) were isolated from the first generation of the EUROSOILS, a reference set of five samples representing the most widespread soil units in the European Union (EU). The EUROSOIL (E)-HA were characterized for their compositional, structural, and functional properties by using chemical methods and spectroscopic techniques, including Fourier transform infrared (FT IR), nuclear magnetic resonance, fluorescence, and electron spin resonance. The E-HAs generally exhibit features typical of soil HAs of similar origin and nature, and differ in their composition, structure, and chemical properties on dependence on the parent soil type, vegetation cover, and land use. The E-HA from the Orthic Podzol under coniferous forest (E5-HA) exhibits the largest oxygen and acidic functional group contents, organic free radical concentration, aromatic polycondensation and humification degree, and the distinct presence of outer-sphere complexed Mn2+ ions. The E-HAs from the Dystric Cambisol under grassland/pasture (E3-HA) and the Orthic Luvisol cultivated for wheat (E4-HA) are generally characterized by a great content of nitrogen-containing and methoxyl groups and polysaccharide structures, small contents of acidic functional groups and free radicals, relatively small aromaticity and humification degree, and the presence of both inner-sphere complexed Cu2+ ions and outer-sphere complexed Mn2+ ions. The E-HAs from the Vertic Cambisol under grassland/meadow (E1-HA) and the Rendzina under broad-leaved tree cover (E2-HA) are characterized by properties that are generally intermediate between those of E5-HA and E3- and E4-HAs, being E1-HA more similar to E5-HA and E2-HA to E3- and E4-HAs. The differences in chemical and physicochemical properties of these E-HAs are expected to affect differently their reactivity toward soil organic and inorganic contaminants.

Reformatsky intermediate. A C-metallated species.

Abstract 13 C-NMR and 1 H-NMR spectra of the Reformatsky reagent from t-butylbr o moacetate, evidence a C-metallated species: within the limits of detectability of the methods, no O-metallated species can be detected in solution.

Structural investigations of humic substances by IR-FT, 13C-NMR spectroscopy and comparison with a maleic oligomer of known structure

Abstract Humic and fulvic acids isolated from an Italian Typic Dystrochrept by conventional means have been investigated by spectroscopic techniques (IR-FT, 13C-NMR). A quantitative 13C-NMR technique was applied. The investigated fulvic acid contains more aliphatic than aromatic moieties. The carboxyl contents of fulvic acid are greater than those of humic acid. In comparison with fulvic acid the humic acid has a higher content of aromatics. The data presented indicate that structural units resembling those of polymaleic acid may be present in fulvic acid but similar structures have not been detected in humic acid.

Decomposition of organic residues in soil: experimental technique and spectroscopic approach

Abstract DRIFT (diffuse reflectance infrared Fourier-transform) spectroscopy was used to follow the early transformations that take place after the incorporation of organic materials in soil. Alfalfa (A), dried maize (DM), laboratory-composted maize (CM), and two commercial composts (YWC and MWC) confined into fiberglass bags were incubated in sand with and without planting with lettuce. DRIFT spectra of these materials before and after incubations were correlated with CO 2 -C evolution and mass, carbon and nitrogen balances. Spectra obtained by successive subtractions allowed us to distinguish between the main classes of biochemical compounds (cellulose, lignin, polypeptides, pectins) and to study their degradation during incubation. Quantitative spectroscopic determination of lignin showed a relative enrichment in the incubated materials. This experimental approach can be applied to studies on the degradation pathway of green manure materials like A, DM and CM but seems less appropriate for commercial composts.

Structural investigations of humic acid from leonardite by spectroscopic methods and thermal analysis

Abstract Humic acid from leonardite, an immature coal, has been examined by spectroscopic methods (UV-VIS, IR-FT, 1 H, 31 P, 13 C-NMR), mass spectrometry (FAB-MS) and thermal analysis. These techniques provided complementary informations. A quantitative 13 C-NMR technique was applied to this humic acid: the aromaticity calculated from the NMR data is high, about 76%, in agreement with mass spectrometric and thermal analysis data.

New Acid-Polyfunctional Water-Soluble Phosphazenes: Synthesis and Spectroscopic Characterization

Abstract Poly [bis(phenoxy)] phosphazene sulfonic acid and its mixed substitution derivatives containing N-methylsulfonamide, sulfonylaminoacetic, and free sulfonic acid functions have been obtained and characterized by IR and 1H-, 31P-, 13C-NMR spectroscopy. The polymers are all water soluble. Poly [bis(4-benzoylphenoxy)] phosphazene sulfonic acid could not be obtained due to chain degradation during the synthesis.

Polyalkylphenyl-sulphonic acid with acid groups of variable strength from compost

The insoluble organic fraction (humin-like material, HLM) from rice hull-dairy cattle compost is well converted into water soluble HLM-sulphonate by reaction in liquid SO3. Microanalytical, potentiometric, molecular weight, and NMR data are consistent with a highly homogeneous polymeric arylsulphonate having 4000 Da MW, 1.3 sulphonic groups per aromatic ring and significant content of carboxylic and phenolic groups. By comparison with structure-property relationships for commercial lignosulphonates derived from the pulp and paper industry, the above arylsulphonate is likely to be a candidate at a variety of applications in the chemical industry and in agriculture. Therefore, sulphonation is a means for upgrading composts HLM to the same uses as for commercial lignosulphonates.

Triterpene glycosides related to quadranguloside from Passiflora quadrangularis

Abstract Two new cyclopropane triterpene glycosides were isolated from the methanol extracts of leaves of Passiflora quadrangularis . On the basis of hydrolysis, spectral evidence and comparison with quadranguloside, these compounds were assigned the structures 9,19-cyclolanosta-22,25-epoxy-3β-21,22( R )-triol-3β- O -gentiobioside and 9,19-cyclolanosta-21,24-epoxy-3β-25,26-triol-3β- O -gentiobioside,respectively. Oleanolic acid-3-sophoroside was also isolated for the first time from a natural source.

Flame Surface Modification of Polyethylene Sheets

High density polyethylene sheets 2 mm thick were flame treated to modify the surface properties. Sheets treated using a flame with air to gas (methane) ratio ∼ 10:1 at different distances between the inner cone tip of the flame and the polymer surface were investigated. Grafting of selected monomers as maleic anhydride, acrylamide and glycidyl methacrylate was attempted by flame treatment of sheets covered with a monomer layer. Good grafting results were obtained with acrylamide and maleic anhydride. The surface temperature-time dependence during the flame treatment was measured with a high resolution thermocouple. Scanning Electron Microscopy (SEM) allowed evidencing a modified thickness of about 120 μm. The chemical surface modification was studied by X ray Photoelectron Spectroscopy (XPS) and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFT). The hydroxyl, carbonyl and carboxyl content was measured after derivatization with reagents containing an elemental tag to facilitate XPS analysis of surface functional groups. In comparison to the untreated polyethylene, wetting tension and contact angle of the flamed materials showed a strong variation. This variation was almost independent of the distance between the flame and the polymer surface. Adhesion between treated polyethylene and a polyurethane adhesive was determined using T-peel test measurements. High adhesion levels were found with flame treated polyethylene at 5 mm distance. XPS results indicate that when adhesion is high, the hydroxyl is in excess compared to the other measured functions, i.e. carbonyl and carboxyl species.

Oxygen-17 NMR Spectroscopy: Effect of Substituents on Chemical Shifts for o− m− p− Substituted Benzoic Acids, Phenylacetic and Methyl Benzoates

Abstract 17O-NMR chemical shifts of several o-,m, and p-substituted benzoic phenylacetic acids and methyl benzoates are reported and discussed. The 17O chemical shifts are correlated with Hammett constant and 13C substituent chemical shift data.