(698a) β-Cyclodextrin – Ionic Liquid Polyurethanes Modified Magnetic Nanoparticles: A Multifunctional Sorbent for Efficient Removal of PFOA, PFOS and Cr(VI) from Water

Authors: 
Badruddoza, A. Z. M., Massachusetts Institute of Technology

Emerging contaminants such as, perfluorinated compounds (PFCs) and heavy metals have raised global concerns due to their potential negative effects on aquatic ecosystems and human health. Their mixtures often present at contaminated sites lies in one of the major challenges in remediating water. Herein, we report a novel multi-functional sorbent (Fe3O4-CDI-IL MNPs), which was fabricated by modifying the Fe3O4 nanoparticle with surface tethered β-cyclodextrin- ionic liquid polyurethanes, for the removal of emerging contaminants and heavy metals from aqueous solutions. In this setting, the hydrophobic cavities of cyclodextrins are expected to capture PFC molecules through the formation of inclusion complexes and ionic liquid (IL) units as the sorption sites for metals. The magnetic sorbent was characterized by FT-IR, ζ -potential, and TGA. The removal efficiencies of both PFOS and PFOA were significantly enhanced due to the contribution of ionic liquid coupled with β-cyclodextrin polymer backbone. The removal efficiencies of PFOA and Cr(VI), unlike that of PFOS were greatly affected by the solution pH. Kinetic results revealed that the adsorption equilibrium of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and Cr(VI) on Fe3O4-CDI-IL MNPs was achieved within 4, 6 and 3 hr, respectively and the adsorption process followed the pseudo-second-order kinetic model. In a monocomponent system, the adsorption behaviors showed a heterogeneous adsorption capacity of 13,200 and 2,500 μg/g for PFOS and PFOA, respectively, and a monolayer adsorption capacity of 2,900 μg/g for Cr(VI) ions. Interestingly, the Cr(VI)â??PFC binary experiments showed sorption reduction of PFCs, but no significant effect on Cr(VI). The adsorption mechanisms of PFCs on Fe3O4-CDI-IL MNPs could be attributed to hydrophobic interactions and electrostatic attraction, while ion-exchange and reduction was responsible for Cr(VI) sorption. Furthermore, Fe3O4-CDI-IL MNPs was readily recovered in an external magnetic field and still maintained high removal efficiency after ten-times recycling tests. This multi-functional sorbent may find potential application in water or wastewater treatment for the efficient removal of coexisting toxic pollutants.