Tuning the sorption properties of amidoxime-functionalized algal/polyethyleneimine beads for La(III) and Dy(III) using EDTA: Impact of metal speciation on selective separation

Amidoximated algal/polyethyleneimine beads are successfully applied for the sorption of two rare earths elements (REEs, Ln(III)): La (light) and Dy (heavy). The properties characterized by FTIR SEM-EDX analyses. pH effect on metal is investigated with a double objective: optimizing recovery separation. In binary solutions, Dy(III) shows slightly higher affinity sorbent than La(III); without significant differences in selectivity. difficult separation REEs can be modulated using EDTA. Playing concentration ligand, La(III) separated from Dy(III). Selectivity coefficient, SCLa/Dy, may reach up to 40–50. Speciation diagrams show that preferential formation Dy-EDTA complexes limits while remains predominant highly sorbed (reduced Dy-competition). Optimum conditions Ln(III) predicted calculation speciation diagrams. concept verified Er(III) (heavy REE). presence EDTA, isotherms (mono-component solutions) present sigmoidal shapes due complexation. Converting total sorbable species (non-complexed EDTA) allows plotting favorable curves (Langmuir equation). fits experimental profiles modified Langmuir equation confirm preference non-complexed species. kinetic fitted Crank highlight contribution resistance intraparticle diffusion control uptake kinetic; this reinforced Metal desorption CaCl2 (50 mM, 2) or EDTA (0.5 6) used (yield: 80–95%), capacity progressively decreases over 3 cycles.