Bioadsorption of Co(II) and Mn(II) in aqueous solutions by the Rhodococcus opacus bacterium

The bioadsorption of Co(II) and Mn(II) in aqueous solutions was evaluated by Rhodococcus opacus inactivated and treated with NaOH, and the physicochemical characterization of the bioadsorbente. The physicochemical characterization of bacteria was performed by scanning electron microscopy coupled to energy dispersive X-ray analyses (SEM-EDS), Fourier transforms infrared spectroscopy (FTIR,) and Zeta Potential (ZP). Likewise, the operating conditions in the process were determined, evaluating biosorbent concentration, initial metal concentration (Ci), pH, and contact time. The experiments were performed at the laboratory, and the bacteria was previously treated with NaOH (0.1M). The interaction between R. opacus and metal ions was confirmed by the variation of isoelectric point (IEP) and functional groups. Removals and uptake of 87.8 % and 24.9 mg/g for Co(II) and 79.9 % and 6.1 mg/g for Mn(II) were achieved under test-operating conditions. These conditions were pH 7, biomass 4 mg/l, Ci 50 mg/l, and 180 minutes of operation time. While for Mn(II): pH 5, biomass 3 mg/l, Ci 5 mg/,l and 10 minutes operation time. The present study shows that R. opacus can be applied to treat effluents containing low concentrations of Co(II) and Mn(II).