Publication detail

Some remarks on the origin of lignite humic acids optical properties

ČECHLOVSKÁ, H. VÁLKOVÁ, D. GRASSET, L. FASUROVÁ, N. KUČERÍK, J.

Original Title

Type

journal article - other

Language

English

Original Abstract

Humic acids (HA) isolated from lignite of South Moravian and North Czech region (leonardite) were characterized by elemental analysis and fluorescence spectroscopy analysis. From both humic acids there were sequentially extracted water soluble fractions, free and bond fatty acids which were consequently characterized by CPMAS 13C-NMR spectroscopy and GC-MS analysis. The respective rests were dissolved in sodium hydroxide and the synchronous fluorescence spectroscopy (SFS) was used to analyze the character of present fluorophores and assess the influence of extracted molecules on the fluorescence of humic acids. The results has revealed a number of essential outcomes for the elaboration of fluorescence records of humic matter: i) based on our and other measurements, the optical properties of humic acids could not be aresult of the superposition of numerous independent chromophores, but rather of their mutual interactions; it seems, that SFS evaluates predominantly hydrophobic core of humic aggregates which has apparently highly aromatic character, ii) the inner core of a humic aggregate do not necessarily consists of condensed structures, the high aromaticity degree can be a consequence of weak interactions of simple aromatic moieties such as pi-pi stacking and CH-pi; iii) the crucial factor in SFS measurement is quenching which can be caused both by molecules present outside and inside of a humic aggregate; iv) due to the unique and complicated secondary structure of humic acids the molecules which are not primarily fluorophores can significantly affect the fluorescence due to their interaction with fluorophores.

Keywords

synchronous fluorescence spectroscopy, lignite humic acids, extractions, supramolecular structure

Authors

ČECHLOVSKÁ, H.; VÁLKOVÁ, D.; GRASSET, L.; FASUROVÁ, N.; KUČERÍK, J.

RIV year

2009

Released

14. 2. 2009

Publisher

Slovnaft Bratislava

Location

Slovensko

ISBN

1335-3055

Periodical

Petroleum and Coal

Year of study

Number

State

Slovak Republic

Pages from

Pages to

Pages count

BibTex

@article{BUT46761,
  author="Hana {Čechlovská} and Dana {Švejdová} and Laurent {Grasset} and Naděžda {Fasurová} and Jiří {Kučerík}",
  title="Some remarks on the origin of lignite humic acids optical properties",
  journal="Petroleum and Coal",
  year="2009",
  volume="51",
  number="1",
  pages="33--44",
  issn="1335-3055"
}