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, named UiO-67-F₂, was synthesised alongside three previously reported materials, namely 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, 20 °C, was high (5.54 and 5.24 mmol g⁻¹, respectively). Furthermore, UiO-67-F₂ exhibited a remarkable PFOA uptake of 928 mg_PFOA per g_MOF in an aqueous solution, which far exceeded that of unmodified UiO-67 (872 mg_PFOA per g_MOF at 1000 mg_PFOA per L_Water). This study has identified strengths and potential applications of the novel UiO-67-F₂, as well as the impact of fluorine functionalization. It also offers some 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.