A Kinetic, Equilibrium, and Thermodynamic Study on the Biosorption of Tl⁺and Cd²⁺byEichhornia crassipesRoots Using Carbon Paste Electrode

Abstract

In this work, Eichhornia crassipes roots were used as a modifier for carbon paste electrode in a biosorption study of thallium (Tl +) and cadmium (Cd 2+) ions. The ions were accumulated on modified electrode surfaces at open circuit potential and analyzed by square wave anodic stripping voltammetry. Before the biosorption study, the effect of ratio of biomass and binder in uptake metal was evaluated. The biosorption study shows that adsorption of ions was dependent on pH. The kinetic study showed that, for both ions, experimental data were well described by the pseudosecond order model (R 2 > 0.99) and the equilibrium was better described by the Langmuir model. The value of dimensionless equilibrium parameter (R L) obtained in the equilibrium study showed that Eichhornia crassipes can be considered an effective biomaterial for Tl + and Cd 2+ removal from an aqueous solution. The thermodynamic parameters calculated, enthalpy (ΔH°), entropy (ΔS°) and Gibbs energy (ΔG°), indicated that the biosorption process was spontaneous and endothermic.

Low-Temperature Synthesis of Magnetic Carbonaceous Materials Coated with Nanosilica for Rapid Adsorption of Methylene Blue

“…For chemisorption it should be 20.9−418.4 kJ mol −1 but for physical adsorption it should be 2.1−20.9 kJ mol −1 . 51 In this case, the value of ΔH°is 51.81 kJ mol −1 , therefore, MB was adsorbed onto MCA@SiO 2 through chemisorption process, which was also predicted by adsorption kinetics. Moreover, positive value of ΔS°indicated increased entropy and disorders at solid−liquid interface (Table 3).…”

“…Nature of adsorption process that is chemisorption or physical adsorption also depends upon value of Δ H °. For chemisorption it should be 20.9–418.4 kJ mol –1 but for physical adsorption it should be 2.1–20.9 kJ mol –1 . In this case, the value of Δ H ° is 51.81 kJ mol –1 , therefore, MB was adsorbed onto MCA@SiO 2 through chemisorption process, which was also predicted by adsorption kinetics.…”