A fluorinated zirconium-based metal-organic framework as a platform for the capture and removal of perfluorinated pollutants from air and water

Abstract

A series of zirconium-based MOFs with acclaimed stability was prepared and their ability to adsorb polyfluorinated pollutants was compared. A novel fluorinated UiO-67 analogue, UiO-67-F2, was synthesised alongside three previously reported materials: UiO-67-NH2, UiO-68-(CF3)2 and UiO-67. The structures were established and confirmed by powder X-Ray diffraction. UiO-67-NH2, UiO-68(CF3)2 and UiO-67-F2 were examined as sorbents for the perfluorinated gas, sulphur hexafluoride (SF₆) from the gaseous phase. The SF₆ uptake of UiO-67-NH2 and UiO-67-F2 at 100 kPa, 293 K, was high (5.54 and 5.24 mmol g ^-1 respectively). UiO-67-F2 exhibited a remarkable perfluorinated octanoic acid (PFOA) uptake of 928 mg_PFOA g ^-1_MOF in an aqueous solution, which far exceeded that of unmodified UiO-67 (872 mg_PFOA g ^-1_MOF at 1 000 mg_PFOA L ^-1_Water PFOA). This study has identified strengths and potential applications of the novel UiO-67-F2 and the impact of fluorine functionalization. The study also offers insight into the structure-property relations of UiO-based MOFs for their use as low-pressure SF6 storage materials and PFAS sorbents intended for water purification under ambient conditions.