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

[摘要] 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; approximate to 0.77 umol/g), 5.0 mg/g (PAA; approximate to 32.16 mol/g), 3.0 mg/g (BPG; approximate to 19.30 mu mol/g), and 2.9 mg/g (DTPADA; approximate to 18.65 mu ol/g). Attaching ligands to the aminated resins greatly improved their REE binding strength and adsorption efficiency. (C) 2019 Elsevier Inc. All rights reserved.

[发布日期] 2019-12-01

[关键词] Lanthanides;Rare earth elements;Adsorption;Chelation;Ion exchange;Adsorption;Selective;Functionalized adsorbents;Metals;Recycling;Resource recovery