Журнал наук о Земле и изменения климата

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Adsorption Kinetics of Cobalt (II) Ions onto Alginate Beads from Aqueous Solutions

Navarro AE, Musaev H, Serrano K and Masud ME

Cobalt is a heavy metal that is commonly used in industrial processes and used in batteries and tanning activities. Time-dependent experiments were carried out to study the adsorption kinetics of cobalt (II) ions onto alginate beads in batch conditions at room temperature. Experiments were carried out in the absence of salt and in a 0.01 M solution of NaNO₃ as a model salt to explore the effect of salinity in the adsorption. The experimental data was fitted to pseudo-first (Lagergren model) and pseudo-second order kinetics. According to the modeling, experimental data is better resembled by the pseudo-second order kinetics as shown by its correlation coefficient, indicating that less than 30 minutes are needed to reach equilibrium. Likewise, experimental data shows that salinity has a negative effect on the adsorption of cobalt (II) ions, reporting maximum adsorption capacities of 230 mg/g and 211 mg/g in the absence and in the presence of salt, respectively. It is hypothesized that electrostatic competition for the adsorption sites occurs due to the presence of Na⁺ ions in the solution. Finally, our results were compared to recently reported data, indicating that alginate beads have better adsorption properties than other naturally-occurring materials like algae, flower wastes and minerals like zeolite and bentonite. This study demonstrated that alginate beads are good candidates for a fast and efficient removal of cobalt (II) ions from solutions.