Influência de íons metálicos na estrutura de substâncias húmicas detectados por espectroscopia.
Abstract
INFLUENCE OF METAL CATIONS IN THE STRUCTURE OF
HUMIC SUBSTANCES AS DETECTED BY SPECTROSCOPY, involves a
study by which starting from precursors of humic substances, some polymers
were obtained, characterized and comparable with samples of humic acids. One
such polymer with similar characteristics with humic acids was obtained by
using as precursors hydroquinone, p-benzoquinone and 4-aminbenzoic acid,
subjected to a synthesis under polymeric oxidation at an alkaline medium. The
following structural characteristics of such polymers were studied in comparison
with humic acids: influence of Cu, Fe and Mn cations in the structure of the
synthesized polymers by spectral characteristica of Fourier Transform Infrared
Spectroscopic (FTIR), absorbance with UV-Vis light, fluorescence; experiments
with Size Exclusion Chromatography (SEC) and Atomic Force Microscopy
(AFM) with the polymers and humic acids. It has been found that the
complexation with the Cu, Fe and Mn cations has affected the structure by
increasing the molecular size as observed by the Size Exclusion
Chromatography. After complexation with the metal cations the FTIR, UV-Vis
and Fluorescence spectra has shown significant changes due to structural
modifications, which indicates complex formation specially with the carboxylic
and phenol groups found in the obtained polymers.