Study of lignite humic acids by modern spectroscopic methods

Study of lignite humic acids by modern spectroscopic methods

Abstract

Humic substances (HS) especially humic acids (HA) are natural organic compounds arising by chemical and biological decomposition of organic matter (plant and animal tissues) and synthetic activity of microorganisms. Humic substances are among the most widely distributed organic materials on the Earth. Of course occurring in brown coal (Leonardites) and lignite, peat, soils, sediments and some other materials. Humic acids represent very important part of organic matter (OM) in lignite. Lignite contains a high proportion of humic acids, which amounts to 80 %. Object of our study was lignite humic acid and standard HA Leonardite (1S104H). Humic acid was extracted from South-Moravian lignite from the mine Mír in Mikulčice, Czech Republic. The lignite HAs were isolated according to the standard IHSS extraction method. Humic acids were characterized by elemental analysis, ultraviolet-visible spectroscopy, infrared spectroscopy and fluorescence spectroscopy. Ratios E2/E3 and E4/E6 (humification index) were calculated from the absorbance of HAs in UV-VIS spectral range. Infrared spectroscopy with Fourier transform is a useful technique in characterization of structure, functional groups and formation modes of HAs. Further, the fluorescence spectra in the emission, excitation, synchronous-scan mode and excitation-emission matrix (EEM) were obtained on alkaline solutions (0,5 M NaOH) of HAs at a concentration of 50 mg/dm3. The long wavelenght of the major peak of lignite HA may be ascribed to the presence higher degree of condensation aromatic ring, large molecular weight and high humification degree. Fluorescence and infrared spectra of lignite HA was compared with Leonardite HA standard (IHSS).

Humic substances (HS) especially humic acids (HA) are natural organic compounds arising by chemical and biological decomposition of organic matter (plant and animal tissues) and synthetic activity of microorganisms. Humic substances are among the most widely distributed organic materials on the Earth. Of course occurring in brown coal (Leonardites) and lignite, peat, soils, sediments and some other materials. Humic acids represent very important part of organic matter (OM) in lignite. Lignite contains a high proportion of humic acids, which amounts to 80 %. Object of our study was lignite humic acid and standard HA Leonardite (1S104H). Humic acid was extracted from South-Moravian lignite from the mine Mír in Mikulčice, Czech Republic. The lignite HAs were isolated according to the standard IHSS extraction method. Humic acids were characterized by elemental analysis, ultraviolet-visible spectroscopy, infrared spectroscopy and fluorescence spectroscopy. Ratios E2/E3 and E4/E6 (humification index) were calculated from the absorbance of HAs in UV-VIS spectral range. Infrared spectroscopy with Fourier transform is a useful technique in characterization of structure, functional groups and formation modes of HAs. Further, the fluorescence spectra in the emission, excitation, synchronous-scan mode and excitation-emission matrix (EEM) were obtained on alkaline solutions (0,5 M NaOH) of HAs at a concentration of 50 mg/dm3. The long wavelenght of the major peak of lignite HA may be ascribed to the presence higher degree of condensation aromatic ring, large molecular weight and high humification degree. Fluorescence and infrared spectra of lignite HA was compared with Leonardite HA standard (IHSS).

humic acids, standard IHSS, modern spectroscopic methods

humic acids, standard IHSS, modern spectroscopic methods

ENEV, V.; KLUČÁKOVÁ, M.

2013

18.06.2012

Chemické listy

Olomouc

0009-2770

CHEMICKE LISTY

106

6

Czech Republic

535

535

1

http://hdl.handle.net/