AVALIAÇÃO DA REMOÇÃO DE CD E ZN DE SOLUÇÃO AQUOSA POR BIOSSORÇÃO E BIOFLOTAÇÃO COM RHODOCOCCUS OPACUS / A STUDY OF CD AND ZN UPTAKE AND REMOVAL BY BIOSORPTION AND BIOFLOTATION USING RHODOCOCCUS OPACUS

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

The search for new technologies for the removal of hazardous metals from wastewater has been focused on several features for the biological materials as such: metal binding and flotation abilities. The aim of this work was to evaluate the biosorption and bioflotation abilities of Rhodococcus opacus for cadmium and zinc removal. Pre and post-characterizations for the microorganism features were performed in terms of: type of surface charge according zeta potential value; relative membrane composition by Gram`s stain and electron microscopy scan (EMS). Parameters for biosorption were studied according to: pH, initial metal concentration and time removal; and for bioflotation: flotation speed, air flow-rate and foam formation, were evaluated. The Cd and Zn uptake capacity by Rhodococcus opacus have been also studied using Langmuir and Freundlich models. Preliminary observations confirmed that R. opacus, corresponds to a grampositive microorganism, with an isoelectric point (IEP) of 2.5, indicating the predominance of acidic groups (polysaccharides and carboxylic molecules) on its membrane composition. Analysis by EMS, showed changes on structure conformation and metal up-take by the microorganism. At pH 7.0 and 26°C, Cd and Zn removals of 60 and 83% were observed from initial concentration of 15 and 5 ppm, respectively. Results showed that metal uptake capacity can be expressed by the Freundlich isotherms for both metals. Kinetics studies demonstrated that biosorption process follows a pseudo- second order model. Bioflotation process showed that R. opacus has excellent features as collector and foaming agent. Around 90% removal of cadmium has been achieved used metal loaded biomass. R. opacus showed to have good metal binding and flotation abilities.

ASSUNTO(S)

cadmio zinc zinco biossorcao biosorption bioflotation bioflotacao cadmium

ACESSO AO ARTIGO

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