Efficient Adsorption and Elimination of Tm³⁺ for Enhanced Seed Germination Using Pillar[5]Arene Polymer

While rare earth elements (REEs) are essential for modern technology, their production methods raise concerns for agriculture. Researchers are now exploring ways to control and recycle REEs pollution, aiming to minimize agricultural impacts and potentially even develop methods to utilize these elements for improved crop yields. Regarding this issue, a new type of pillar[5]arene polymer (Pol-P[5]-BTZP) has been designed and synthesized by click reaction to enhance the efficiency of adsorption and recovery of rare earth metals. This polymer incorporates the unique structure of 2,6-di-1,2,3-triazolyl-pyridine. The results of various analyses revealed that Pol-P[5]-BTZP exhibits excellent thermal stability, a high specific surface area, and well-distributed networks of micropores and mesoporous structures. The adsorption capacity of Pol-P[5]-BTZP for Tm³⁺, a representative REE, was evaluated using the Langmuir and Freundlich isothermal adsorption models with a maximum adsorption capacity (Qmax) of 127.71 mg/g. Furthermore, the versatility of Pol-P[5]-BTZP in adsorption and recovering various REEs was tested. In addition to its adsorption capabilities, the potential of Pol-P[5]-BTZP for rare earth recovery and reuse was assessed through experiments on the impact of Tm³⁺ and La³⁺ on seed germination. These experiments demonstrated the wide-ranging applicability of Pol-P[5]-BTZP in recovering and reusing REEs for green agriculture.