Imidazolium-Functionalized Ionic Porous Organic Polymer for Efficient Removal of Oxo-Anions Pollutants from Water

The development of highly efficacious materials for the removal of toxic heavy metal-based oxo-anions is of utmost importance. Herein, an ionic porous organic polymer (designated as HB-IPOP) was synthesized through a quaternization reaction between hexa(imidazole-1-yl)benzene and 5,5'-Bis(bromomethyl)-2,2'-bipyridine. HB-IPOP exhibited high saturation uptake capacities, specifically 292 mg·g^-1 for Cr₂O₇^2- and 531 mg·g^-1 for ReO₄^-, and demonstrated exceptional selectivity for both Cr₂O₇^2- and ReO₄^-. Additionally, HB-IPOP demonstrates high recyclability, allowing its reuse over at least five cycles. DFT calculations confirmed that the superior interaction sites and binding energies of HB-IPOP with Cr₂O₇^2- and ReO₄^- outperform the affinities of other competing anions. This theoretical validation aligns with the experimentally observed high capacity and selectivity of HB-IPOP for these oxo-anions. Hence, HB-IPOP emerges as a promising candidate to replace current adsorbent materials in the effective removal of Cr₂O₇^2- and TcO₄^- anions from water.