Publication detail

Conformational Changes in Aqueous Solutions of Humic Acids

KLUČÁKOVÁ, M. KARGEROVÁ, A. NOVÁČKOVÁ, K.

Original Title

Type

abstract

Language

English

Original Abstract

Conformational changes of humic acids in two different aqueous solutions (NaCl and NaOH) are studied by means of High Resolution Ultrasound Spectrometry. It is based on the measurement of parameters of ultrasonic waves propagating through the sample. Attenuation describes the decay of the amplitude of the ultrasonic wave with distance traveled. Ultrasonic velocity is the speed of this wave and is related to the wavelength and the frequency of oscillation of the deformation. It is determined by the density and elasticity of the sample, which is strongly influenced by the molecular arrangement. The elastic response is generally dominant. The minimum of ultrasonic velocity was observed for humic content of 1 g.dm-3 in 0,1M NaCl. Compressibility was practically the same up to this concentration and then they decreased. This confirms that the organization of humic particles in diluted and concentrated humic sols is different. The decrease in compressibility showed the forming of more rigid structures which could cause the decrease in humic binding ability. This conformational change was confirmed also by the strong increase in ultrasound attenuation for humic sols in NaCl. On the other hand, no minimum but two breaks were observed, if humic acids were dissolved in 0,1M NaOH. First one was measured at 0,1 g.dm-3, second one at 1 g.dm-3. Increase in attenation was lower for humic solution in NaOH comparing with NaCl. Our results confurmed that dissolved humic acids may be micelle-like, which are supramolecular assemblies of small entities. If micelle-like structures form at high concentrations, a portion of humic reactive functional groups may be less accessible for e.g. metal ions as they might be entrapped in the more hydrophobic interior.

Keywords

humic acids, conformation, molecular organization, stability

Authors

KLUČÁKOVÁ, M.; KARGEROVÁ, A.; NOVÁČKOVÁ, K.

Released

14. 9. 2011

Publisher

Czech Chemical Society

Location

Brno

ISBN

0009-2770

Periodical

Chemické listy

Year of study

105

Number

State

Czech Republic

Pages from

896

Pages to

897

Pages count

BibTex

@misc{BUT74079,
  author="KLUČÁKOVÁ, M. and KARGEROVÁ, A. and NOVÁČKOVÁ, K.",
  title="Conformational Changes in Aqueous Solutions of Humic Acids",
  booktitle="Chemické listy",
  year="2011",
  journal="Chemické listy",
  volume="105",
  number="18",
  pages="896--897",
  publisher="Czech Chemical Society",
  address="Brno",
  issn="0009-2770",
  note="abstract"
}