Fabricating Tetraphenylethylene-Based Ionic Porous Organic Polymers for Efficient Sequestration of Toxic Iodine and...

Water pollution, driven by rapid industrialization, has become a global issue, threatening human health and ecosystems. The contamination of water sources with radioactive waste, heavy metals, and toxic oxoanions has led to a scarcity of clean drinking water. Ionic porous organic polymers (iPOPs) offer a superior way for water purification due to their multiple binding sites and ion-exchange properties, which enable them to remove contaminants through electrostatic interactions efficiently. Moreover, iPOPs can be regenerated through simple desorption processes and reused over multiple cycles, making them cost-effective. Herein, we have synthesized chemically and thermally robust iPOPs (TPE-C1 and TPE-C4) using a one-step nucleophilic substitution reaction and utilized them for the removal of radioactive waste (iodine in vapor, aqueous, and organic phases) along with various hazardous oxoanions (Cr₂O₇^2-, MnO₄^-, and ReO₄^-) from water via an ion-exchange process with high uptake capacities. To the best of our knowledge, the adsorption capacity of TPE-C1 for I₃^- (4.3 g/g) is the highest in the field of iPOPs. Both the iPOPs showed ultrafast kinetics (>90% removal within 50-150 s), with a kinetic constant value as high as 0.14 mg g^-1 min^-1 (for permanganate ion), which enhances their efficiency and applicability. In the presence of a large excess (100 times) of competitive anions, the efficiency of TPE-C1 remained mostly unaffected, demonstrating its excellent selectivity. Further, density functional theory (DFT) studies confirmed the presence of electrostatic interactions between the iPOPs and the oxoanions, as well as determined the binding sites and binding energy for the iPOPs toward the pollutants. These iPOPs were recyclable for up to five cycles with no loss in efficiency and maintained consistent performance across various water sources (sea, river, and lake), reflecting their practical applicability. For real-time use, a column-based setup was prepared using TPE-C1, which could achieve >98% removal of these toxic pollutants. With high adsorption capacity, superfast kinetics, superior selectivity, and facile recyclability, these iPOPs offer an affordable and effective solution for removing a wide variety of pollutants and advancing water treatment technologies.