Adsorption Rare Earth Metal Ions from Aqueous Solution by Polyamidoamine Dendrimer Functionalized Soy Hull

A polyamidoamine (PAMAM) dendrimer functionalized soy hull (PDFSH) was prepared and used to adsorb rare earth metal ions (La3+, Nd3+ and Sm3+) from aqueous solution. Physicochemical factors such as contact time, initial rare earth metal ions concentration, and adsorption temperature affecting magnitude of rare earth metal ions adsorption were investigated, and the kinetics, isotherm and thermodynamics of the adsorption process were further researched. The natural soy hull and polyamidoamine dendrimer functionalized soy hull were characterized by scanning electron microscope. The results showed that the equilibrium data was found to follow Freundlich and Tempkin isotherm. The adsorption results revealed that the equilibrium time was about 4 h for three rare earth metal ions, and the pseudo-second-order kinetic model fits very well with the dynamical adsorption behavior of the rare earth metal ions. Moreover, The thermodynamic investigation demonstrated that the adsorption process was spontaneous and endothermic, and the enthalpy change (ΔHθ), the entropy change (ΔSθ), and free energy change (ΔGθ) of the adsorption process were calculated with adsorption isotherm data and basic thermodynamic relations.