Regulating steric hindrance in difunctionalized porous aromatic frameworks for the selective separation of Pb(II)
Xuan Ding, Jiayi Liu, Hui Shi, Yi Zhou, Lei Zhou, Wei Ren, Penghui Shao, Liming Yang, Derun Zhao, Yun Wei, Xubiao Luo
Abstract
Efficient and selective removal of Pb(II) from wastewater with complex matrix remains a challenging task. Porous aromatic frameworks (PAFs) with predesigned functional building blocks provide a favorable platform for the selective separation of Pb(II). Herein, the bifunctional SPAFs with the introduction of -OH and -SO 3 H were synthesized through rationally optimizing their steric hindrance. As a result, the SPAF-0.75 exhibits favorable adsorption capacity of Pb(II) (212.34 mg g −1 ), which is 22 times larger than pristine framework. Competition experiment indicates that SPAF-0.75 possess the selective removal of Pb(II) without interfering from co-existing metal ions. The removal rate of SPAF-0.75 still retain at 100% after six successive cycles. The DFT calculation illustrates that -OH and -SO 3 H are co-participate in the process of capturing Pb(II), revealing SPAF-0.75 preferred removal of Pb(II) owing to the lowest adsorption energy (Δ E ab = −3.99 eV). This study extend the understanding of the structure-property relationship and facilitate new possibilities for PAFs.