Imidazolium-Functionalized Chemically Robust Ionic Porous Organic Polymers (iPOPs) toward Toxic Oxo-Pollutants Capture from Water

Abstract

Fabricating new and efficient materials aimed at containment of water contamination, in particular removing toxic heavy metal based oxo-anions (e. g. CrO42−, TcO4−) holds paramount importance. In this work, we report two new highly stable imidazolium based ionic porous organic polymers (iPOPs) decorated with multiple interaction sites along with electrostatics driven adsorptive removal of such oxo-anions from water. Both the iPOPs (namely, iPOP-3 and iPOP-4) exhibited rapid sieving kinetics and very high saturation uptake capacity for CrO42− anions (170 and 141 mg g−1 for iPOP-3 and iPOP-4 respectively) and ReO4− (515.5 and 350.3 mg g−1 for iPOP-3 and iPOP-4 respectively), where ReO4− anions being the non-radioactive surrogative counterpart of radioactive TcO4− ions. Noticeably, both iPOPs showed exceptional selectivity towards CrO42− and ReO4− even in presence of several other concurrent anions such as Br−, Cl−, SO42−, NO3− etc. The theoretical binding energy calculations via DFT method further confirmed the preferential interaction sites as well as binding energies of both iPOPs towards CrO42− and ReO4− over all other competing anions which corroborates with the experimental high capacity and selectivity of iPOPs toward such oxo-anions.