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Characterization of fungal melanins and soil humic acids by chemical analysis and infrared spectroscopy 总被引:5,自引:0,他引:5
Summary Humic acids from two Brazilian topsoils under savanna grassland and five soil fungal melanins were characterized by elemental, functional group and infrared analysis. C, N, total acidity, COOH, and phenolic OH contents were within the ranges reported for several other fungal melanins and soil humic acids. Compared with the soil humic acids, the infrared spectra of the fungal melanins showed greater detail, indicative of higher aliphaticity. They were similar to the type III infrared spectra of humic acids, which are characteristically high in proteinaceous material and polysaccharides. The infrared spectra of the humic acids from the two Brazilian soils studied were classified as type I, which includes most soil humic acids. Notwithstanding the greater detail, in some areas the fungal melanin spectra were similar to those reported for other fungal melanins and humic acids of different origins. The probable contribution of the melanic fungi to the formation of soil humic polymers is discussed. 相似文献
2.
Liliam Cristina Angelo Antonio Salvio Mangrich Karen Mary Mantovani Sailer Santos dos Santos 《Journal of Soils and Sediments》2014,14(2):353-359
Purpose
Charcoal is utilized in Brazil for the metallurgical industry. Small size pieces, called charcoal fines, are rejected and sometimes are used to produce energy by burning. This charcoal can be used as soil conditioner to improve retention of metal ions in soil. However, changing the charcoal's surface chemistry via oxidation may increase retention of metal ions.Materials and methods
Two kinds of oxidants were employed, nitric acid and selenium dioxide/hydrogen peroxide. Vanadyl ion (VO2+) and copper ion (Cu2+) were utilized as probe to study the metal ion complexation by the partially oxidized charcoal obtained. FTIR and EPR spectroscopy were used to characterize the materials.Results and discussion
Oxidation with nitric acid increased nitrogen content, while oxidation with SeO2/H2O2 elevated carbon content of treated charcoals. Organic free radicals (OFRs) with the unpaired electron in p orbitals of aromatic structures were confirmed by the EPR g-factors that ranged from 2.0038 to 2.0031. The oxidation with selenium dioxide/hydrogen peroxide formed charcoal with largest quantity of OFR. Loading charcoal with VO2+ and Cu2+ resulted in formation of complexes were oxygen acted as coordination atom. The formed complexes were of axial symmetry. The configurations around the Cu2+ ions were: CUNCu2+ complex (more stable square planar symmetry) and CFNCu2+ complex (less stable distorted tetrahedral configuration). Both complexes had oxygen as coordinating atoms. CFNVO2+ and CFSeVO2+ complexes presented complexation sites of axial symmetry, C4v, with oxygen as coordinating atoms.Conclusions
The oxidative treatment of charcoal with SeO2/H2O2 is more appropriate to produce soil organic conditioner for complexation of metal ions. 相似文献3.
R. C. Gomes R. R. R. Coelho L. F. Linhares A. S. Mangrich 《Biology and Fertility of Soils》1996,21(1-2):84-88
Eleven actinomycete melanins were characterized by elemental and functional group and infrared analysis. A soil humic acid from a Brazilian topsoil, a darkred latosol under savanna grassland, analysed previously, was used for comparative purposes. C, N, total acidity, COOH, and phenolic OH contents were within the ranges reported for soil humic acids and fungal melanins. Compared to the soil humic acid, the actinomycete melanins showed greater detail, indicative of higher aliphaticity. Most of these were, in varying degrees, similar to the type III IR spectra of humic acids, which are characteristically high in proteinaceous material, and with variable amounts of polysaccharides. The exceptions were two melanin spectra that showed more resemblance to the humic acid from the dark-red latosol, which belongs to the type I spectra of soil humic acids, a category that includes most soil humic acids. The probable participation of melanic actinomycetes in the formation of humic polymers in discussed. 相似文献
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A. S. Mangrich A. W. Lermen E. J. Santos R. C. Gomes R. R. R. Coelho L. F. Linhares N. Senesi 《Biology and Fertility of Soils》1998,26(4):341-345
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.
Received: 9 April 1997 相似文献
5.
Matos Tassya T. S. Mangrich Antônio S. Cardoso Estela M. C. Schultz Juliana Fornari Mayara R. Wisniewski Alberto Carregosa Ingrid S. C. 《Journal of Soils and Sediments》2019,19(1):286-295
Journal of Soils and Sediments - The ability of biochars prepared from pyrolysis of guava pulp and seed industrial wastes to form complexes with the ions vanadyl (VO2+), a Pearson hard acid, and... 相似文献
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