Navegando por Palavras-chave "Sorção"

Agora exibindo 1 - 1 de 1
  • Imagem de Miniatura
    Item
    Acesso aberto (Open Access)
    Importância da especiação química na remoção do manganês do meio aquoso
    (Universidade Federal de São Paulo, 2015-12-21) Novais, Paloma da Silva [UNIFESP]; Hernandez, Raul Bonne [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Studies indicate that the occurrence of manganese (Mn>100 µg/l) and microcystin (MC> 1.0 µg/l) in surface waters can generate neuro risks (toxicological). Sorption has been presented as a great alternative to water treatment processes, due to the wide availability of natural resources (minerals and biopolymers). In this study, it was hypothesized that mixtures of materials with sorption capacity could improve the sorption processes, a phenomenon that can be influenced by the chemical speciation. Thus, the study aimed to evaluate the role of chemical speciation in Mn removal efficiency of aqueous media. For this purpose, materials have been tested such as coconut fiber, zeolite and chitosan batch and immobilized in single and mixed composition column for removal of chemical species of Mn (Mn (II), Mn (III), Mn (VII)). Removal best results were obtained with columns packed bed of mixed composition. For all species of Mn used, with an initial concentration of 145 µg/l, after passing through the columns, the Mn concentrations decreased almost 9 times for a removal efficiency of over 99%. When, the manganese concentration increased 3.5 times, the decrease in concentration in the filtrate was almost 9 times, after having been filtered 100 ml at 150 min with removal yields of about 95%. In both cases, the manganese content in solution was below the permitted by legislation CONAMA 357/05 (100 µg /l) and EPA (50 µg /l). The process by slowly downward filtration is explained by Thomas model (r2 > 0.9433), based on the Langmuir isotherm. The model indicates a maximum capacity adsorption column, which depends on the chemical speciation: MnCl2 (3,644 mg/g) > KMnO4 (3,216 mg/g) > Mn(II)Cit (3,098 mg/g). These results confirmed the potential negative effect of complexing species in the adsorption process, such as citrate. This dynamic was maintained for fast filtration, even in the presence of microcystins (RR, YR, LR); however, there was a decrease of approximately 35% removal of Mn. Additionally, the system under study showed a different selectivity in the removal of microcystin MC-RR> MC-YR> MC-LR, the waters tested.