Environmentally Friendly β‑Cyclodextrin–Ionic Liquid Polyurethane-Modified Magnetic Sorbent for the Removal of PFOA, PFOS, and Cr(VI) from Water

Emerging contaminants such as perfluorinated compounds (PFCs) and heavy metals are of increasing concerns due to their detrimental effects on environment and human health. Their mixtures are often present at contaminated sites that pose a challenge in water remediation. Herein, we report a multifunctional magnetic sorbent (Fe₃O₄-CDI-IL MNPs) that was prepared by modifying the magnetic Fe₃O₄ nanoparticle with β<i>-</i>cyclodextrin–ionic liquid (β<i>-</i>CD-IL) polyurethanes for the removal of perfluorooctanesulfonate (PFOS), perfluorooctanoic acid (PFOA), and Cr­(VI) from aqueous solution. The successful grafting of the β<i>-</i>CD-IL polymer on magnetic nanoparticles was confirmed by FTIR, ζ -potential, TGA, and VSM. The sorption behaviors of Fe₃O₄-CDI-IL MNPs were investigated in terms of sorption kinetics, isotherms, simultaneous removal capability, and reusability. The kinetic results showed that the sorption of PFOS, PFOA, and Cr­(VI) reached equilibrium within 4, 6, and 3 h, respectively, and the pseudo-second-order kinetic model best described the kinetic data. The solution pH had more obvious effects on the sorption of PFOA and Cr­(VI) than that of PFOS. The coupling of ionic liquid with the β<i>-</i>CD polymer backbone could significantly enhance the removal efficiencies of both PFOS and PFOA. The sorption isotherms indicated that the heterogeneous sorption capacities of Fe₃O₄-CDI-IL MNPs were 13,200 and 2500 μg/g for PFOS and PFOA, respectively, and the monolayer sorption capacity was 2600 μg/g for Cr­(VI) ions. The Cr­(VI)-PFC binary sorption experiments exhibited a decrease in sorption capacities for PFCs, but the removal of Cr­(VI) was unaffected with the introduction of PFCs as co-contaminants. The hydrophobic interactions and electrostatic attraction were mainly involved in the PFC sorption process, whereas the ion exchange and reduction was responsible for Cr­(VI) sorption. In addition, Fe₃O₄-CDI-IL MNPs could be readily recovered with a permanent magnet, regenerated, and reused at least 10 times without any significant efficiency loss. This multifunctional sorbent thus shows potential in the removal of coexisting toxic contaminants from water or wastewater

Controlled Fabrication of α-GaOOH and α-Ga₂O₃ Self-Assembly and Its Superior Photocatalytic Activity

In this article, we report the fabrication of gallium oxide (α-Ga₂O₃) microspheres (GOMs) by a self-assembly process. Gallium nitrate with oxalic acid in a hydrothermal process results in α-GaOOH, which was further converted into gallium oxide by calcinations at 450 °C for 3 h. We first report the formation of various morphological α-GaOOH by using the above-mentioned methodology. The influence of hydrothermal temperature and time on the crystal structure and its morphology was studied, and the results indicated that hydrothermal temperature played an important role in the final morphology of α-GaOOH. The flower-like α-GaOOH formed at 175 °C is converted into rodlike α-Ga₂O₃ after calcination at 450 °C, and the α-GaOOH microsphere and microrod formed at 200 and 225 °C retained their morphology during the calcination process, respectively. The synthesized α-GaOOH and α-Ga₂O₃ were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), and nitrogen adsorption analysis. The XRD patterns indicated that well-crystallized α-GaOOH and α-Ga₂O₃ were formed in a hydrothermal and calcination process, respectively. The FE-SEM images indicated the formation of well-organized microspheres and microflowers, which were composed of nanoparticles and nanoplates, respectively. The photocatalytic degradation of Acid Orange 7 (AO7) dye and Cr(VI) reduction by using the synthesized GOM under UV light irradiation was investigated. The photocatalytic experiment showed superior photocatalytic activity of GOM having a higher efficiency than TiO₂. We propose a plausible mechanism for the formation of various morphologies of α-GaOOH and α-Ga₂O<sub>3.</sub