Functionalized Polymeric Nanoparticles for Yttrium Recovery by Chelating Effect

Abstract

Polymethyl methacrylate nanoparticles functionalized with three different compounds, acrylic acid (AA), curcumin (CUR), and fumaramide (FA), were tested in a two-step solid-liquid extraction process (extraction and stripping) for yttrium recovery. In both stages, the best conditions were determined: pH, solid-liquid ratio and the compound with the highest affinity for yttrium recovery, obtaining 90% of efficiency for both stages in a single work cycle. The results obtained by SEM ruled out the growing of nanoparticles by swelling and confirmed the formation of structural arrangements by the addition of the metal to the system. In addition, there is evidence that the recovery process can be selective considering the mixing of rare earth elements through changes in pH. Using isothermal titration calorimetry (ITC), the thermodynamic properties of the extraction process were calculated, understanding the system as the union of a macromolecule and a ligand. The results showed that the extraction process was spontaneous and highly entropic.

Keywords: [Y] recovery; extraction process; extraction selectivity; rare earths; stripping process.

Figure 1

Theoretical scheme of yttrium extraction, by the formation of chelating complexes for three different systems: AA, CUR, and FA.

Figure 1

Theoretical scheme of yttrium extraction, by the formation of chelating complexes for three different systems: AA, CUR, and FA.

Figure 2

Yttrium extraction with the three different latex series, modifying the solids content.

Figure 3

Yttrium extraction with the three different latex series, modifying the solid/liquid ratio.

Figure 4

UV-Vis spectra of latex with AA, FA, and CUR (black dotted line) all at 10 wt.%. Spectra of latex after extraction process (red line).

Figure 5

Average particle size, Z–potential, and pH as a function of the concentration of [Y] added to the system. Solid/liquid ratio = 0.1 g/mL, [Y] concentration = 0.015 mol/L.

Figure 6

${pH}_{{\displaystyle \frac{1}{2}}}$ ranges for selective yttrium and europium extraction. with each latex series. (solid/liquid ratio 0.1 g/mL).

Figure 7

Extraction selectivity [Y] vs. [Eu]. CUR-5wt.%, concentration of 1000 ppm (solid/liquid ratio 0.1 g/mL).

Figure 8

SEM images at 50,000× of functionalized polymeric nanoparticles with (a) AA-5wt.%, (b) CUR-5wt.%, and (c) FA-15wt.% after the extraction process with [Y]. Arrangements as pearl necklaces are also observed in the polymeric particles (indicated for red dotted circles).

Figure 9

Stripping of [Y] with varying pH, 120 min, and 1 g latex per 10 mL of water. [Y] 900 mg/L initial concentration.

Figure 10

Thermograms (top) and binding isotherms (bottom) for the determination of thermodynamic parameters of the latex–metal bond. Heat molar ($Q{n}^{-1}$) as a function of molar ratio between metal ions and functional groups.