REMOÇÃO DE PB, CR E CU POR PROCESSO COMBINADO DE BIOSSORÇÃO/BIOFLOTAÇÃO UTILIZANDO A CEPA RHODOCOCCUS OPACUS / REMOVAL OF PB, CR AND CU BY A COMBINED BIOSORPTION / BIOFLOTATION PROCESS USING A RHODOCOCCUS OPACUS STRAINT

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

This work evaluated the potential of the Rhodococcus opacus strain as a biosorbent for the removal of Pb(II), Cr(III) and Cu(II) from aqueous solutions by Biosorption/bioflotation process, through experimental batch tests. The operational parameters investigated in the biosorption´s stage were: pH of the solution, biomass concentration, contact time and initial metal concentration. In the separation of the loaded biomass by bioflotation process for dispersed air were evaluated the flotation time and the foam characteristics. The characteristics of the microorganism surface and the involved interaction mechanisms in the heavy metals sorption by R. opacus, were evaluated based in the potential zeta measurements, infrared spectroscopy and electron microscopy scanning analysis. The solution initial pH value affected metals sorption, the adjusted pH values in the sorption and the flotation stage were 5.0 for the Pb(II) and pH value of 6.0 for the Cr(III) and Cu(II). The experiments of biosorption kinetics showed that the process is relatively fast and in sixty minutes of contact between the biomass and the metal solution were reached the maximum metal uptake capacities. The data pertaining to the uptake capacity of the R. opacus in function of the metal ion concentration fitted to the Langmuir isotherm model for the tree species in study, where the maximum uptake capacities obtained were: 94.3; 72.9 and 32.2 mg.g-1 for Pb (II), Cr(III) and Cu(II), respectively. The kinetics of sorption of Pb(II), Cr(III) and Cu(II) were modeled using a pseudo second order rate equation. The affinity order of R. opacus for the three metals under study has been established as: Pb(II)>Cr(III)>Cu(II). The selectivity of the biomass for the Pb(II) over the other two metals was well exhibited by the results obtained in the biosorption and bioflotation. This difference in the affinity of the R. opacus can be attributed to the physiochemical properties of these metals, amongst them atomic weight, ionic radio and electronegativity. The uptake capacity of ions Pb(II) for the biomass was reduced by the presence of other metallic species in the system, and the results showed that the Cr(III) has greater affinity for the biomass than the others ions. In the bioflotation, it was found that the microorganism presents excellent characteristics as collector and foaming agent, reaching 94%, 54% and 43% removal of lead, chromium and copper, respectively, to 20 mg.l-1 of concentration. The results of this study showed that R. opacus has important features for the heavy metal removal; moreover, the results also showed that R. opacus is especially effective biosorbent for the removal of Pb(II).

ASSUNTO(S)

bioflotacao biosorption rhodococcus opacus metais pesados heavy metals bioflotation rhodococcus opacus biossorcao

ACESSO AO ARTIGO

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