Three calixpyrrole-based porous organic polymers (P1-P3) have been prepared with the goal of removing organic micropollutants from water. A bowl-shaped α,α,α,α-tetraalkynyl calixpyrrole and diketopyrrolopyrrole monomer were crosslinked via Sonogashira coupling to produce a three-dimensional network polymer P1. This polymer, which proved too hydrophobic for use as an adsorbent, was converted to the corresponding neutral polymer P2 (containing carboxylic acid groups) and its anionic derivative (polymer P3 containing carboxylate anion groups) through post-polymerization structural modification of the pendent tert-butyl esters. The anionic polymer P3 outperformed its precursor neutral polymer P2 as determined from screening studies involving a variety of model organic micropollutants of different charge, hydrophilicity and functionality, including dyes, simple aromatics, and two cationic pesticides. Polymer P3 proved particularly effective for cationic micropollutants. The theoretical maximum adsorption capacity (qmax,e) of P3 determined from the corresponding Langmuir isotherms reached 454 mg g-1 for the dye methylene blue, 344 mg g-1 for the pesticide paraquat, and 495 mg g-1 for diquat, respectively. These uptake values are signiﬁcantly higher than those of most synthetic adsorbent materials reported to date. The present findings thus lend support to the conclusion that calixpyrrole-based porous organic polymers may have a role to play in water puriﬁcation.
Bibliographical noteKAUST Repository Item: Exported on 2021-02-21
Acknowledged KAUST grant number(s): OSR-2019-CRG-4032
Acknowledgements: H. Wang is grateful for support from the National Natural Science Foundation of China (21975153) and the Shanghai Pujiang Program (2019PJD017). X. Ji. acknowledges initial funding from the Huazhong University of Science and Technology, where he is being supported by Fundamental Research Funds for the Central Universities (grant 2020kfyXJJS013). X. Ji. is also grateful for support from the National Natural Science Foundation of China (No. 22001087), and the Open Fund of Hubei Key Laboratory of Material Chemistry and Service Failure, Huazhong University of Science and Technology (2020MCF08). Acknowledgment is also made to Shanghai University, the Robert A. Welch Foundation (grant F-0018 to J.L.S.), a ConTex grant provided by The University of Texas System (2019-06A to J.L.S.), and the King Abdullah University of Science and Technology (OSR-2019-CRG-4032 to J.L.S. and N.M.K.).