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

Jonathan C Callura; Kedar M Perkins; John P Baltrus; Newell R Washburn; David A Dzombak; Athanasios K Karamalidis

doi:10.1016/j.jcis.2019.08.097

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

J Colloid Interface Sci. 2019 Dec 1:557:465-477. doi: 10.1016/j.jcis.2019.08.097. Epub 2019 Aug 27.

Authors

Jonathan C Callura¹, Kedar M Perkins², John P Baltrus³, Newell R Washburn², David A Dzombak¹, Athanasios K Karamalidis⁴

Affiliations

¹ Carnegie Mellon University, Department of Civil and Environmental Engineering, Pittsburgh, PA, USA.
² Carnegie Mellon University, Department of Chemistry, Pittsburgh, PA, USA.
³ U.S. DOE National Energy Technology Laboratory, Pittsburgh, PA, USA.
⁴ Carnegie Mellon University, Department of Civil and Environmental Engineering, Pittsburgh, PA, USA; Pennsylvania State University, Department of Energy and Mineral Engineering, University Park, PA 16802, USA. Electronic address: akk5742@psu.edu.

PMID: 31541916
DOI: 10.1016/j.jcis.2019.08.097

Abstract

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 q_Max 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.

Keywords: Adsorption; Chelation; Functionalized adsorbents; Ion exchange; Lanthanides; Metals; Rare earth elements; Recycling; Resource recovery; Selective.