Substâncias húmicas aquáticas: fracionamento molecular e caracterização de rearranjos internos após complexação com íons metálicos

AUTOR(ES)

Sargentini Junior, Ézio, Rocha, Julio Cesar, Rosa, André Henrique, Zara, Luiz Fabricio, Santos, Ademir dos

FONTE

Química Nova

DATA DE PUBLICAÇÃO

2001-06

RESUMO

The aquatic humic substances (AHS) investigated in this study were conventionally isolated from Rio Negro waters - Amazonas State/Brazil by means of the collector XAD 8. A special five-stage tangential-flow ultrafiltration device was used for analytical fractionation of AHS. The fractionation patterns (6 fractions each) showed that metal traces remaining in AHS after their XAD 8 isolation have different size distributions. For instance, the major percentage of traces of Ni, Cu, Zn, Cd and Pb (determined using ICP-AES) was preferably complexed by molecules with relatively high molecular size (30-100 kDa) and the following complexation order was characterized: F2 >> F1 = F4 = F5 > F3 > F6. Moreover, the species formed between AHS and metals prepared by spiking, showed distribution patterns changing as a function of the complexation time (ageing process), indicating a slow transformation process and an inner rearrangements in the binding sites within the AHS molecules.

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