Wei Xuyi, Mao Xiaohui, Han Junwei, Qin Wenqing, Zeng Hongbo
School of Minerals Processing & Bioengineering, Central South University, Changsha 410083, China.
Department of Chemical and Materials Engineering, University of Alberta, Edmonton T6G 1H9, Canada; College of Materials Science and Engineering, Donghua University, 2999 North Renmin Road, Shanghai 201620, China.
J Hazard Mater. 2024 Nov 5;479:135679. doi: 10.1016/j.jhazmat.2024.135679. Epub 2024 Aug 28.
Efficient recovery of rare earth elements (REEs) from wastewater is crucial for advancing resource utilization and environmental protection. Herein, a novel nitrogen-rich hydrogel adsorbent (PEI-ALG@KLN) was synthesized by modifying coated kaolinite-alginate composite hydrogels with polyethylenimine through polyelectrolyte interactions and Schiff's base reaction. Various characterizations revealed that the high selective adsorption capacity of Ho (155 mg/g) and Nd (125 mg/g) on PEI-ALG@KLN is due to a combination of REEs (Lewis acids) via coordination interactions with nitrogen-containing functional groups (Lewis bases) and electrostatic interactions; its adsorption capacity remains more than 85 % after five adsorption-desorption cycles. In waste NdFeB magnet hydrometallurgical wastewater, the recovery rate of PEI-ALG@KLN for Nd and Dy can reach more than 93 %, whereas that of Fe is only 5.04 %. Machine learning prediction was used to evaluate adsorbent properties via different predictive models, with the random forest (RF) model showing superior predictive accuracy. The order of significance for adsorption capacity was pH > time > initial concentration > electronegativity > ion radius, as indicated by the RF model feature importance analysis and SHapley Additive exPlanations values. These results confirm that PEI-ALG@KLN has considerable potential in the selective extraction of REEs from wastewater.
从废水中高效回收稀土元素（REEs）对于推进资源利用和环境保护至关重要。在此，通过聚电解质相互作用和席夫碱反应，用聚乙烯亚胺对包覆高岭土 - 海藻酸盐复合水凝胶进行改性，合成了一种新型富氮水凝胶吸附剂（PEI - ALG@KLN）。各种表征表明，PEI - ALG@KLN对Ho（155 mg/g）和Nd（125 mg/g）具有高选择性吸附能力，这是由于稀土元素（路易斯酸）通过与含氮官能团（路易斯碱）的配位相互作用和静电相互作用相结合；经过五次吸附 - 解吸循环后，其吸附容量仍保持在85%以上。在废钕铁硼磁体湿法冶金废水中，PEI - ALG@KLN对Nd和Dy的回收率可达93%以上，而对Fe的回收率仅为5.04%。利用机器学习预测通过不同的预测模型评估吸附剂性能，随机森林（RF）模型显示出卓越的预测准确性。RF模型特征重要性分析和SHapley加性解释值表明，吸附容量的重要性顺序为pH > 时间 > 初始浓度 > 电负性 > 离子半径。这些结果证实，PEI - ALG@KLN在从废水中选择性提取稀土元素方面具有相当大的潜力。
