Biosorptive flotation of nickel and aluminum ions from aqueous solution

Air flotation is an efficient way to separate light particulates and oils from wastewaters. Nickel (II) and aluminum (III) removal by the combined biosorption and flotation process named biosorptive flotation was studied in laboratory scale. The Rhodococcus opacus strain was used to assist the removal of the toxic metals by biosorption. The effects of relevant parameters such solution pH, uptake capacity, time and air flow rate flotation were evaluated. Electrokinetic measurements were carried out to determine the isoelectric point (IEP) of the R. opacus. The zeta potential profile of the bacteria was deeply affected by the presence of the Ni (II) and Al (III) and their speciation. The maximum sorption capacity was found to be 7.63 and 41.59 mg g(-1) at pH 5.0 for Ni (II) and Al (III), respectively (initial concentration of 50 mg L-1) and temperature 25 degrees C. Moreover, the ionic strength of the water solution showed a deleterious role in the biosorption process. The recoveries of the loaded biomass with nickel (II) and aluminum (III) by flotation were found to be in the order of 90 and 93%, respectively at pH around 5. The higher floatability for both species was obtained in a maximum time of 20 minutes. (C) 2011 Elsevier B.V. All rights reserved.