Preparation of large-size UiO-66-S films based on radiation grafted substrates and its mercury ion-removal performance in artificial plasma

To develop efficient adsorption materials to improve the cure rate of heavy metal poisoning, we designed and prepared large size metal-organic framework (MOF) UiO-66-S films based on irradiation-grafting pretreated substrate, and investigated the selectivity of these films with multi-heavy metal ions in artificial plasma. The grafting density of maleic anhydride on a substrate was quantitatively measured by chemical titration and the effects of the radiation parameters on the grafting density were studied. The grafting density could be tuned from 0.10 to 75.80 nmol/cm² by changing the radiation parameters. The investigation of surface wettability and mechanical property proved that the irradiation-grafting process changed the surface wettability of maleic anhydride grafting substrate but did not affect its mechanical property. We prepared UiO-66-S films by in-situ growth and postsynthesis modification on the substrate with the grafting density of 14.94 nmol/cm² and characterized the film by attenuated total reflection flourier transformed infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscope, which showed how the nanothickness continuous MOF film was obtained. The UiO-66-S films exhibited high selectivity to mercury ions in the artificial plasma with multi-ions coexisting; the removal ratio reached more than 50%. The adsorption process followed the pseudo-second-order kinetic equation. Moreover, the mercury ion-removal rate of the UiO-66-S films in the artificial plasma was faster than that in pure water. (authors)