Isotherm and kinetic sorption of some lanthanides and iron from aqueous solution by aluminum silicotitante exchanger

ABSTRACT

Sorption of La³⁺, Eu³⁺, and Fe³⁺ onto new synthetic inorganic ion exchange material of aluminum silicotitante was investigated. The aluminum silicotitante (EX₁, EX₂, and EX₃) are synthetic with different concentration ratio (0.1:0.1:0.003, 0.1:0.1:0.1, and 0.1:0.1:0.1) at aging time 4, 4, and 1 day, respectively. The equilibrium kinetic for La³⁺, Eu³⁺, and Fe³⁺ onto EX₁, EX₂, and EX₃ materials takes about 120 min which is considered as a fast kinetic process. Sorption results were fitted using different kinetic models such as pseudo-first-order, pseudo-second order, and intraparticle diffusion models. The results indicated that the sorption of La³⁺, Eu³⁺, and Fe³⁺ onto EX₁, EX₂, and EX₃ materials is highly fit with the pseudo-second order model. Equilibrium data were described by the Langmuir, Freundlich isotherm models. The Langmuir isotherm model was fitted to the experimental data better than the Freundlich isotherm. The thermodynamics parameters (positive values of ΔH°, ΔS° and negative values of ΔG°) indicated the binding systems between the materials and adsorbate were endothermic, entropy gained and spontaneous in nature. The experimental data indicated that, aluminum silicotitante could be used as an efficient sorbent for La³⁺, Eu³⁺, and Fe³⁺. Maximum sorption % at equilibrium is 92.7, 99.0, and 78.5% for La³⁺, Eu³⁺, and Fe³⁺, respectively.

KEYWORDS:

• Ion exchanger
• mathematical modelling
• rare earth elements
• sorption
• thermodynamic