A cationic porous organic polymer for high-capacity, fast, and selective capture of anionic pollutants

The emerging ionic porous organic materials have achieved various applications in different fields, however, there is limited study on using them to capture ionic pollutants from water. Here we demonstrate a facile method to prepare a cationic porous organic polymer via catalyst-free Schiff base reaction. The imidazolium-based polymer (ImPOP-1) was constructed through copolymerizing cationic molecules with low-cost benzidine. The as-prepared ImPOP-1 exhibits high capacity (e.g., 476.2 mg g^-1 for Pd (II) and 578.5 mg g^-1 for AO7^-), excellent selectivity (e.g., more than 99% removal efficiency for Pd (II) in the presence of 100 times excess of SO₄^2-), and fast kinetics (e.g., 98.6% removal efficiency within 5 min for Pd (II) ions) to the anionic pollutants including organic dyes and heavy metal ions. The excellent performance on scavenging anionic pollutants from water suggests that ImPOP-1 holds promising potential as an ion exchange material for water remediation.