Biosorptive removal of cadmium from aqueous solutions using a Streptomyces lunalinharesii strain

The aim of this work was to study the fundamental aspects of a combined biosorption/bioflotation system applied to cadmium removal from aqueous solutions using a Streptomyces lunalinharesii strain. The main sorption conditions, such as solution pH, biomass concentration and the initial concentration of cadmium were evaluated on the metal uptake performance. The characterization of the biosorbent was carried out through zeta potential measurements, FTIR spectra and SEM images.From the sorption studies, it was observed that the metal removal was significant, around 55% in a single stage, and took place at pH around 5.0; biosorption studies showed that the Langmuir model fitted properly well. Moreover, the maximum cadmium uptake was about 24.8 mg g−1. The kinetic works showed that the pseudo-second-order model appropriately fitted the experimental data. The integrated process of biosorption–bioflotation achieved a cadmium removal value around 61%.

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► Removal of cadmium by a biosorption/bioflotation procedure.
► Experimental equilibrium data were fitted to isotherms models.
► The adsorption process was very fast and equilibrium was reached after 10 min.
► The FTIR and SEM analyses show the presence of cadmium in biomass surface.