Adsorption kinetics, thermodynamics, and isotherm studies for functionalized lanthanide-chelating resins

[Display omitted] Conventional ion exchange resins are widely utilized to remove metals from aqueous solutions, but their limited selectivity precludes dilute ion extraction. This research investigated the adsorption performance of ligand-functionalized resins towards rare earth elements (REE). Func...

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Bibliographic Details
Published in:Journal of colloid and interface science 2019-12, Vol.557 (C), p.465-477
Main Authors: Callura, Jonathan C., Perkins, Kedar M., Baltrus, John P., Washburn, Newell R., Dzombak, David A., Karamalidis, Athanasios K.
Format: Article
Language:English
Subjects:
Adsorption
Chelation
Functionalized adsorbents
Ion exchange
Lanthanides
Metals
Rare earth elements
Recycling
Resource recovery
Selective
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Summary:[Display omitted] Conventional ion exchange resins are widely utilized to remove metals from aqueous solutions, but their limited selectivity precludes dilute ion extraction. This research investigated the adsorption performance of ligand-functionalized resins towards rare earth elements (REE). Functionalized resin particles were synthesized by grafting different ligands (diethylenetriaminepentaacetic dianhydride (DTPADA), phosphonoacetic acid (PAA), or N,N-bis(phosphonomethyl)glycine (BPG)) onto pre-aminated polymeric adsorbents (diameter ∼ 0.6 mm). Lanthanide uptake trends were evaluated for the functionalized resins using batch adsorption experiments with a mixture of three REEs (Nd, Gd, and Ho at 0.1–1000 mg/L each). Resin physical-chemical properties were determined by measuring their surface area, ligand concentrations, and acidity constants. The aminated supports contained 4.0 mmol/g primary amines, and ligand densities for the functionalized resins were 0.33 mmol/g (PAA), 0.22 mmol/g (BPG), and 0.42 mmol/g (DTPADA). Kinetic studies revealed that the functionalized resins followed pseudo-second order binding kinetics with rates limited by intraparticle diffusion. Capacity estimates for total REE adsorption based on Langmuir qMax were 0.12 mg/g (amine; ≈ 0.77 µmol/g), 5.0 mg/g (PAA; ≈ 32.16 µmol/g), 3.0 mg/g (BPG; ≈ 19.30 µmol/g), and 2.9 mg/g (DTPADA; ≈ 18.65 µmol/g). Attaching ligands to the aminated resins greatly improved their REE binding strength and adsorption efficiency.
ISSN:0021-9797
1095-7103
DOI:10.1016/j.jcis.2019.08.097