Propriedades ácido-base e de complexação de ácidos húmico e fúlvico isolados de vermicomposto
AUTOR(ES)
Colombo, Sandro de Miranda, Santos, Luciana Bagdeve de Oliveira dos, Masini, Jorge Cesar, Abate, Gilberto
FONTE
Química Nova
DATA DE PUBLICAÇÃO
2007-10
RESUMO
Proton binding properties of humic and fulvic acids were studied by potentiometric titration. Carboxylic groups were the predominant ionizable sites in comparison to phenolic and amine groups. Total acidity of fulvic acid was 12 x 10-3 mol g-1, a number significantly higher than that obtained for humic acid (5.2 x 10-3 mol g-1). Copper ion binding was evaluated at pH 4, 5 and 6 by potentiometric titration with an ion selective electrode for Cu(II). Differential stability constants and complexation capacities were systematically higher for humic acid, despite its lower number of ionizable sites in comparison with fulvic acid.
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