Publication detail

Methylation of humic acids – the impact on the reactivity, chemical composition and properties of HAs studied by spectrometric techniques

ENEV, V. KLUČÁKOVÁ, M. SMILEK, J. DOSKOČIL, L.

Original Title

Type

abstract

Language

English

Original Abstract

The aim of this work was study chemical composition, chemical properties and reactivity of methylated standard humic acid (mHA) and its native form. Humic acid (standard sample of humic acid – International Humic Substances Society – Leonardite HA 1S104H) was modified by methylation. All samples of Leonardite HAs were characterized by elemental analysis (EA), total organic carbon analysis (TOC), ultraviolet-visible spectroscopy (UV/Vis), Fourier transform infrared spectroscopy (FTIR), steady-state fluorescence spectroscopy and nuclear magnetic resonance (13C NMR). The elemental composition was determined by a CHNS/O Microanalyser Flash 1112 Carlo Erba. Oxygen content was calculated by difference: O % = 100 – (C + H + N + S) %, and data obtained were corrected for moisture and ash content. Absorption coefficients (EET/EBz, E250/E365 and E465/E665) of Leonardite HAs were calculated from the absorbance values. Infrared spectroscopy is a useful technique in characterization of structure, functional groups and formation modes of HAs. For the fluorescence experiments the final concentration of the HAs was adjusted to 10 mg/L. The pH-value of the samples was adjusted to seven using a standard phosphate buffer. Fluorescence mono-dimensional spectra and total luminescence spectra (TLS) of HAs were obtained using steady-state fluorescence spectroscopy. All fluorescence spectra were performed on a Horiba Scientific Fluorolog. Total luminescence spectra (TLS) were obtained in the form of excitation/emission matrix (EEM) by scanning the wavelength emission over the range of 300–600 nm, also the excitation wavelength was in 5 nm steps from 240 to 550 nm. The EEM spectrum of ultrapure water (Mili-Q) was obtained, and it was subtracted from the EEMs of all samples examined to decrease the influence from the 1st- and 2nd-order Raman scattering. Fluorescence index (Milori index and HIX) of HAs was calculated from the area of the emission spectra. The fluorescence intensity (IF) values (in CPS) of samples were corrected using method of Lakowicz1. 13C NMR spectra of Leonardite HAs were obtained with a Bruker Avance III NMR spectrometer at an observation frequency of 125.8 MHz for 13C. The approximate number of scans was 25.000. Aromaticity (fa), hydrophilicity and hydrophobicity ratio (Hfi/Hfo) and biological activity (BiA) of HAs were calculated from the area of the NMR spectra.

Keywords

humic acids, methylation, methyl esters, elemental analysis, UV/Vis, FTIR, 13C NMR and fluorescence spectroscopy, NMR parameters, aromaticity, hydrophilicity and hydrophobicity ratio, biological activity

Authors

ENEV, V.; KLUČÁKOVÁ, M.; SMILEK, J.; DOSKOČIL, L.

Released

8. 6. 2015

Publisher

European Colloid & Interface Society

Location

Kraków, Poland, EU

ISBN

NEUVEDENO

Pages from

111

Pages to

111

Pages count

BibTex

@misc{BUT114924,
  author="Vojtěch {Enev} and Martina {Klučáková} and Jiří {Smilek} and Leoš {Doskočil}",
  title="Methylation of humic acids – the impact on the reactivity, chemical composition and properties of HAs studied by spectrometric techniques",
  booktitle="15th European Student Colloid Conference – Book of abstract",
  year="2015",
  edition="1",
  pages="111--111",
  publisher="European Colloid & Interface Society",
  address="Kraków, Poland, EU",
  note="abstract"
}