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BIBTEX RIS

Distribuição de metais e caracterização das constantes de troca entre espécies metálicas e frações húmicas aquáticas de diferentes tamanhos moleculares

2002; Brazilian Chemical Society; Volume: 25; Issue: 6b Linguagem: Inglês

10.1590/s0100-40422002000700011

ISSN

1678-7064

Autores

Adriana Barbosa Araújo, André Henrique Rosa, Júlio César Rocha, Luciane Pimenta Cruz Romão,

Tópico(s)

Analytical chemistry methods development

Resumo

HUMIC FRACTIONS WITH DIFFERENT MOLECULAR SIZES.In this work the metal distribution and exchange constants between metal species and aquatic humic fractions with different molecular sizes were studied.The aquatic humic substances (AHS) were extracted by XAD-8 resin from water sample collected from Itapitanguí river, São Paulo State, Brazil.The AHS were fractionated in six fractions with different molecular sizes (>100 -<5 kDa) and characterized by several techniques.Molar ratios H/C suggested higher aromaticity for fractions F 1 and F 6 whereas molar ratios C/N didn´t show any differences regarding the humification degree between the fractions.The UV-Vis absorbance a 254 /a 436 ratio showed higher results for F 4 and F 5 , probably by less condensed features.FTIR studies showed high similarity in the functional groups in the fractions.The highest percentage of traces of Co, Al, Fe, Mn, Cu, Zn and Ni (determined by ICP-AES) was preferably complexed by fractions F 3 and F 4 with a greater amount of dissolved organic carbon (DOC).In addition, the exchange constants, determined by ultrafiltration method, showed complexes AHS-Fe and AHS-Al with higher stability than complexes AHS-Co in all fractions.

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