Relative Lability of Trace Metals Complexed in Aquatic Humic Substances Using Ion-Exchanger Cellulose-Hyphan
نویسندگان
چکیده
Neste estudo as frações metálicas, complexadas por substâncias húmicas aquáticas (SH) foram caracterizadas como lábeis/inertes em função do pH, tempo de complexação e concentração de SH. As SH foram extraídas por ultrafiltração e complexadas com íons metálicos bivalentes. Essas frações foram caracterizadas por processo de troca iônica utilizando resina celulósica Hyphan e procedimento em batelada. Os metais foram determinados por espectrometria de absorção atômica. Os resultados mostram diminuição dos coeficientes de distribuição (Kd) na presença de SH e que a labilidade relativa das frações metálicas complexadas pelas SH é influenciada pelo tempo de complexação, pH e concentração de SH. Até cerca de 15 min, a troca iônica en tre os metais complexados pela SH e a resina se comporta como reação de 2 ordem. Após esse período, o processo de troca é mais lento caracterizando uma cinética de 1 ordem. Os resultados permitem estabelecer a seguinte ordem de labilidade relativa para as frações metálicas complexadas por SH: Pb > Mn > Cd, Ni > Cu.
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