Simultaneous biosorption of Cd(II), Ni(II) and Pb(II) onto a brown macroalgae Fucus vesiculosus: Mono- and...

Due to the anthropic activities, several heavy metal ions are introduced into the environment, impacting ecosystems and local activities. In this context, the biosorption process using algae represents an alternative form for these compounds remediation due to the advantages derived from the biosorbent and process efficiency. Thus, the present study evaluated Cadmium (Cd(II)), Nickel (Ni(II)) and Lead (Pb(II)) remediation from aqueous media in mono- and multi-component systems. The biosorbent was characterized in terms of its morphology and composition and parameters involving equilibrium, kinetics, and thermodynamics were investigated. Lastly, the sample was considered in a real surface water sample remediation impacted by a mining dam rupture. Except for Freundlich, all isotherm models tested satisfactorily adjusted to the experimental data for a mono-component system. The maximum biosorption capacities (q_m) were 143.2 ± 7.5, 70.1 ± 1.9, 516.3 ± 12.5 mg g^-1 for Cd(II), Ni(II) and Pb(II) ions, respectively. When binary systems were considered, an antagonism effect was observed. The biosorption of Cd(II) was drastically affected by the presence of Ni(II), while Pb(II) biosorption in general was less affected by other metals presence. As observed for the binary system, the worst effect in the ternary system was observed for Cd(II) biosorption, being significantly affected by Ni(II) and Pb(II) presence. Overall, the biosorption order in mono- and multi-component systems was found to be Pb(II) ≫ Cd(II) > Ni(II). The affinity for the metals ions was also observed by Elovich's desorption constant, in which a_Pb(II)≪a_Cd(II)a_Cd(II), achieving an equilibrium passed 49 min. From the stages involved in biosorption process, film diffusion presented the greatest contribution as control-stage obtaining a lower diffusion coefficient in all cases. The process was spontaneous in all temperature range evaluated, considered exothermic for all metal ions evaluated. Iron, manganese and nickel concentrations in real surface water samples were higher than the allowed by the Brazilian National Environment Council (CONAMA). Comparing the hazard index values before and after the biosorption process, a reduction superior to 8 × was observed (HI_before: 3.36, HI_after: 0.40), in which there was no non-carcinogenic risk imposed to the surrounding population after the treatment applied.