Ion-imprinted cellulose fibril-reinforced aerogels for efficient and selective recovery of Nd(III) from low concentration wastewater

Rare earth elements (REEs) are indispensable for advanced technologies, and their recovery from low-concentration industrial wastewater is of great significance for resource utilization and environmental protection. However, the recovery is often hindered by insufficient adsorption capacity and severe interference from coexisting ions. Herein, an ion-imprinted aerogel (PPN@CP-IP) was developed by polymerizing 2-hydroxyethyl 2-methyl-2-propenoate phosphate in the presence of phosphorylated cellulose fibrils using Nd(III) as template. The adsorption kinetics and isotherms were well fitted by the pseudo-second-order and Langmuir models, respectively, indicating chemisorption-dominated monolayer adsorption. PPN@CP-IP exhibited a maximum adsorption capacity of 198.8 mg/g for Nd(III). When the Fe(III) concentration was four times that of Nd(III), the distribution coefficient for Nd(III) remained high at 12202 mL/g. Additionally, after nine adsorption–desorption cycles, the adsorption and desorption efficiencies remained 89.27% and 90.13%, respectively. Adsorption was mainly attributed to electrostatic attraction and coordination between Nd(III) and hydroxyl/phosphate groups. The influencing factors under single-variable and multivariable conditions were investigated using the XGBoost machine learning model. The aerogel was applied in actual waste NdFeB magnet leaching solution, the adsorption capacity of Nd(III) was as high as 167.9 mg/g, while that of iron ions was only 7.3 mg/g. This work provides a robust strategy for highly selective REEs recovery from complex low-concentration wastewater, offering a promising pathway for sustainable rare earth resource recycling and hazardous waste treatment.