Carnegie Mellon University, Department of Civil and Environmental Engineering, Pittsburgh, PA, USA.
Carnegie Mellon University, Department of Chemistry, Pittsburgh, PA, USA.
J Colloid Interface Sci. 2019 Dec 1;557:465-477. doi: 10.1016/j.jcis.2019.08.097. Epub 2019 Aug 27.
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 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.
传统的离子交换树脂广泛用于从水溶液中去除金属，但它们的选择性有限，无法进行稀释离子提取。本研究调查了配体功能化树脂对稀土元素（REE）的吸附性能。通过将不同的配体（二乙烯三胺五乙酸二酐（DTPADA）、膦酸基乙酸（PAA）或 N，N-双（膦酸甲基）甘氨酸（BPG））接枝到预胺化聚合物吸附剂（直径约为 0.6mm）上合成功能化树脂颗粒。通过使用三种 REE（Nd、Gd 和 Ho，每种浓度为 0.1-1000mg/L）的混合物进行批吸附实验，评估了功能化树脂对镧系元素的摄取趋势。通过测量比表面积、配体浓度和酸度常数来确定树脂的物理化学性质。胺化载体含有 4.0mmol/g 的伯胺，功能化树脂的配体密度分别为 0.33mmol/g（PAA）、0.22mmol/g（BPG）和 0.42mmol/g（DTPADA）。动力学研究表明，功能化树脂遵循准二级结合动力学，速率受颗粒内扩散限制。基于 Langmuir q 的总 REE 吸附容量估计值分别为 0.12mg/g（胺基；约 0.77µmol/g）、5.0mg/g（PAA；约 32.16µmol/g）、3.0mg/g（BPG；约 19.30µmol/g）和 2.9mg/g（DTPADA；约 18.65µmol/g）。将配体连接到胺化树脂上大大提高了它们的 REE 结合强度和吸附效率。
