Synthesis and performance studies of functionalized metal-organic framework UiO-66 composites in water bodies

Metal-organic framework (MOF) materials are common adsorbents in water treatment in recent years. In this study, UiO-66 and Ce-UiO-66 were synthesized using a one-pot hydrothermal method for the removal of different pollutants especially tetracycline (TC) from wastewater. By optimizing the optimal preparation conditions of UiO-66 and Ce-UiO-66, materials were analyzed by using SEM, XRD, FTIR, TGA, and XPS techniques, and the adsorption effects of TC, Triclosan (TCS), Methyl Orange (MO), Methylene Blue (MB), and Bisphenol A (BPA) before and after modification with UiO-66 were evaluated. Results showed that TC removal by Ce-UiO-66 could reach 60.34 % before optimization, but TC removal efficiency could reach 92.87 % under the optimal synthesis conditions (nCe/nZr = 0.8, synthesis temperature 120 °C, reaction time 24 h). Ce was successfully loaded onto the surface of UiO-66, and UiO-66′s structure remained unchanged during the loading process. Ce-UiO-66 displayed a good performance for pollutants tested compared to UiO-66 especially TC. The isothermal adsorption is consistent with the Freundlich model, indicating the adsorption process is a non-uniform multilayer adsorption. The mechanism suggests that the doping of Ce increases UiO-66′s active sites, which enhances the electrostatic attraction, π-π conjugation and hydrogen bonding synergism with TC, and ultimately improves its adsorption effect. Overall, this work would serve as blueprint for further research into functionalized MOF materials for the removal of other pollutants.