Photo-responsive imprinted cellulose nanocrystalline aerogels for selective terbium recovery and controlled desorption

Conventional adsorbents have the bottleneck of struggling to balance adsorption and desorption efficiencies, adsorbents with high selectivity tend to require high energy consumption for desorption and are prone to secondary pollution. The development of sustainable adsorbents with high selective adsorption performance and eco-friendly regeneration is essential. In this work, cellulose nanocrystalline imprinted aerogels (SP-IA) with smart-responsive properties were synthesized by using aminated cellulose nanocrystals as the substrate, incorporating methoxy-spiropyran as the photo-responsive monomer, and applying ion-imprinting and freeze-drying techniques. The ligand structures formed by incorporating diglycolic anhydride synergistically interacted with methoxy-spiropyran, improving the capture efficiency of SP-IA for terbium ions. Under the condition of pH 5.0, SP-IA had the optimum adsorption capacity of up to 74.10 mg g −1 . SP-IA showed excellent specific recognition of terbium ions in the complex rare earth solution with separation constant as high as 2382 mL g −1 . The green desorption of SP-IA can be realized by switching the illumination condition from UV to visible light. The desorption rate of SP-IA was over 87 %, and the decrease in adsorption capacity after five cycles was significantly smaller than that of other aerogels, maintaining approximately 86 % of initial value. The selective capture and harmless release of terbium ions from SP-IA could be realized by switching between UV and visible light, respectively. The responsive aerogel broadens the potential application of responsive adsorbents for recovery of rare earth elements from e-waste leachate.