Synthesis of a green ALG@KLN adsorbent for high-efficient recovery of rare earth elements from aqueous solution
Xuyi Wei, Xiaohui Mao, Wenqing Qin, Hongbo Zeng, Junwei Han
Abstract
The increasing consumption of rare earth elements (REEs) and disposal of REE-containing wastes pose a threat to resources and environment. Hence, it is important to achieve efficient REEs recovery while use eco-friendly methods. Herein, natural kaolinite is loaded on alginate hydrogel to prepare ALG@KLN composites via a facile one-step cross-link reaction without any hazardous chemicals. The characterizations of ALG@KLN, adsorption isotherms, adsorption kinetics, and desorption were investigated by SEM-EDS, XPS, FT-IR, and Zeta-potential. The maximum adsorption capacity of Gd (Ⅲ), Y (Ⅲ), Ho (Ⅲ), and Nd (Ⅲ) reached 74.40, 84.48, 85.18, and 75.17 mg/g, respectively. The adsorption kinetics and isotherm were well fitted to pseudo-second-order model and Langmuir model, respectively. The ∼2 mm diameter ALG@KLN can be easily collected and reused. The presence of Na + , Mg 2+ , and Al 3+ has a minor effect on the adsorption of REEs. The adsorption mechanism is mainly via the chemical chelation of oxygen-containing functional groups and electrostatic interaction on negatively charged surface of ALG@KLN. In addition, the cost of ALG@KLN is as low as ∼0.041 USD/gram. This work greatly contributes to the development of economical and eco-friendly REE adsorbents, which plays an important role in sustainable development.