Determination of the equilibrium, kinetic and thermodynamic parameters of the batch biosorption of uranium ions onto Cystoseria indica algae biomass
Sustainable process-product development & green chemistry
Environmental Engineering & Management (T1-3P)
Keywords: Biosorption; Uranium; Cystoseria indica; Equilibrium; Kinetic
Biosorption equilibrium, kinetics and thermodynamics of uranium ions to Cystoseria indica were studied in a batch system with respect to temperature and initial metal ion concentration for protonated and non-protonated states. Algae biomass exhibited the highest uranium uptake capacity at 15 °C at an initial uranium ion concentration of 350 mg l−1 and an initial pH of 4.5 for protonated state. Biosorption capacity decreased from 163.73 to 147.79 mg g−1 with an increase in temperature from 15 to 45 °C at this initial uranium concentration. Freundlich and Langmuir isotherm models were applied to experimental equilibrium data of uranium biosorption depending on temperature. Equilibrium data fitted very well to Langmuir model for both states of Cystoseria indica algae. The saturation type kinetic model was applied to experimental data at different temperatures changing from 15 to 45 °C to describe the batch biosorption kinetics assuming that the external mass transfer limitations in the system can be neglected and biosorption is chemical sorption controlled. Using the Arrhenius, equation the activation energy of biosorption (EA) was determined as -9.40 and -6.63 kJ mole−1 for protonated and non-protonated respectively. Using the thermodynamic equilibrium coefficients obtained at different temperatures, the thermodynamic constants of biosorption (ΔG, ΔH and ΔS°) were also evaluated.
