Pyridinium-Functionalized Ionic Porous Organic Polymer for Rapid Scavenging of Oxoanions from Water

Metal oxoanions adversely affect the food chain through bioaccumulation and biomagnification. Therefore, they are among the major freshwater contaminants that require immediate remediation. Although several adsorbents are developed over the years for sequestering these micropollutants, the selective removal of oxoanions remains still a formidable challenge. Herein, pyridinium and triazine-based ionic porous organic polymer, iPOP-Cl, developed through a Brønsted acid-catalyzed aminal formation reaction, is reported as a suitable anion exchange material for the selective removal of metal oxoanions from wastewater. The positively charged nitrogen centers, along with exchangeable chloride counter-ions in the porous polymer, allow facile oxoanion uptake. iPOP-Cl is found to be a selective scavenger of permanganate (MnO₄ ^- ) and dichromate (Cr₂ O₇ ^2- ) from water in the presence of a high concentration of competing anions generally found in brackish water. The material exhibits fast sorption kinetics, a high uptake capacity (333 mg g^-1 for MnO₄ ^- and 358 mg g^-1 for Cr₂ O₇ ^2- ), and excellent recyclability.