Biosorption of nickel(II) and copper(II) ions from synthetic and real effluents by alginate-based biosorbent produced from seaweed Sargassum sp
2019
Barquilha, Carlos E. R. | Cossich, Eneida S. | Tavares, Célia R. G. | da Silva, Edson A.
In this study, the alginate-based biosorbent produced from seaweed Sargassum sp. was used in biosorption of Ni²⁺ and Cu²⁺ ions from synthetic solutions and real electroplating effluents. Biosorption kinetics, isotherms, pH effect, thermodynamic parameters, and sorption/desorption cycles were also evaluated. Kinetic studies show the sorption equilibrium can be obtained within 180 min for Ni²⁺ ions and 360 min for Cu²⁺ ions, and the adsorption kinetics data are well described by the pseudo-second order and diffusion in spherical adsorbents. Langmuir model can be well used to describe the biosorption isotherm data. The maximum sorption capacity (qₘₐₓ) and Langmuir constant (b) were up to 1.147 mmol g⁻¹ and 1.139 L mmol⁻¹ for Ni²⁺ ions and 1.640 mmol g⁻¹ and 4.645 L mmol⁻¹ for Cu²⁺ ions. The calculated thermodynamic parameters (ΔG°, ΔH°, and ΔS°) showed that the biosorption of Ni²⁺ and Cu²⁺ ions are predominantly a chemical phenomenon of endothermic nature, favorable, and spontaneous at the temperature ranges of 293–313 K. Partial desorption of the Ni²⁺ and Cu²⁺ ions on the biosorbent was achieved using acidic and saline eluents, allowing the biosorbent to be used in new sorption/desorption cycles. EDX analysis suggests an ion exchange mechanism between calcium ions on the biosorbent and target metals. Biosorption of Ni²⁺ and Cu²⁺ from real electroplating effluents with high concentrations of light metals becomes highly competitive, decreasing the amount of Ni²⁺ and Cu²⁺ ions biosorbed due to the ionic strength effect.
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