Extraction and Characterization of Aquatic Humic Substances (AHS) Extracted from Samples Collected in Serra de Itabaiana National Park, Sergipe State, Brazil.

Abstract

This work describes the study of the complexation capacity (CC) of the aquatic humic substances (AHS) extracted from water samples collected in the Serra de Itabaiana National Park (Sergipe) by the metal ions Mn, Ni, Zn, Cu, and Pb, as well as the evaluation of the concentration of total metals of the water samples. The physical and chemical parameters of the water samples were determined: pH, temperature, electrical conductivity, and DOC, as well as the determination of the total metals were quantified by ICP OES. The AHS was extracted with XAD 8 resin according to the procedure recognized by the International Humic Substances Society (IHSS), and were characterized by TGA, elemental analysis, and FTIR, subsequently was studied the CC of the AHS by the metallic ions Cu, Mn, Ni, Pb. and Zn by the ultrafiltration method. The pH value of the sample studied presented a value below the values established by CONAMA Resolution No 357, however the electrical conductivity value is in accordance with Ordinance No 2914 of the Ministry of Health. The concentrations of the total metals are in accordance with the CONAMA Resolution No. 357, except for Pb. The AHS showed three main processes of mass loss (according to the TGA/DTGA curves), the FTIR spectra showed the characteristic bands of tha AHS. The CC of the AHS by metal ions established the following decreasing order: Mn(II) > Ni(II) > Zn(II) >> Cu(II) > Pb(II). These results reinforce that the AHS can be classified as natural complexing agents that play an important role in the environment.