Wrinkle structure on multifunctional MOFs to facilitate PPCPs adsorption in wastewater

A novel multifunctional metal-organic frameworks (MOFs) UiO-66@Fe3O4@UiO-66 (UiO = University of Oslo) was fabricated to adsorb pharmaceuticals and personal care products (PPCPs) under near neutral conditions. We designed a wrinkle structure on the surface of UiO-66@Fe3O4@UiO-66 by seeded growth strategy. These wrinkles were composed of Fe3O4 nanoparticles and outermost UiO-66. It made the specific surface area of the MOFs increases, and provided multiple active sites for a representative pollutant salicylic acid (SA) adsorption. Moreover, lattice defects formed during secondary growth facilitating the coordination interaction between SA and the secondary building unit of UiO-66@Fe3O4@UiO-66 under near neutral conditions. These advantages made the adsorption capacity of per unit mass UiO-66 in UiO-66@Fe3O4@UiO-66 about 42% higher than that of the pristine UiO-66, and the removal rate of 1 mg L-1 SA reach 64.5% in real wastewater. Furthermore, magnetic Fe3O4 particles in the wrinkles exhibited outstanding magnetic separation performance. So that UiO-66@Fe3O4@UiO-66 can be effectively separated from the liquid media and regenerated after adsorption. The results show that the wrinkled MOFs could be used as an excellent candidate for SA adsorption in real wastewater. More importantly, this strategy could guide the preparation of different kind of MOFs to adsorb PPCPs in wastewater.