Computational Investigation of Adsorptive Removal of Pb

Abstract

Adsorption using metal-organic frameworks (MOFs) such as UiO-66 has shown great promise in remediating water sources contaminated with toxic heavy metals such as Pb 2þ , but detailed information about the adsorption process remains limited. In this article, we gained mechanistic insights into Pb 2þ adsorption using both functionalised and defective UiO-66 by performing density functional theory calculations using cluster models. Our benchmarked approach led to a computational model of solvated Pb 2þ (a hemidirected Pb(H 2 O) 6 2þ complex) fully consistent with experimental reports. The analysis of Pb 2þ adsorption using functionalised UiO-66 determined that factors such as electrostatic attraction, chelation, and limited constraints on the Pb 2þ coordination geometry lead to enhanced binding affinity. For these reasons, UiO-66-COOwas identified as the most promising functionalised MOF, consistent with experimental literature. We additionally explored a novel aspect of Pb 2þ adsorption by UiO-66: the role of missing linker defects that often characterise this MOF. We found that the defects expected to form in an aqueous environment can act as excellent adsorption sites for Pb 2þ and the preferred adsorption geometry is again determined by electrostatic attraction, chelation, and constraints on the Pb 2þ coordination geometry. Overall, we conclude that functional groups and defect sites can both contribute to Pb 2þ adsorption and our study provides crucial design principles for improving the UiO-66 MOF performance in toxic Pb 2þ removal from water.

Lead-Based Flow Battery Based on New Pb-Based Anolyte Chemistry

“…DFT calculations were performed on the PbBr­(H 2 O) n + complexes with 6–8 water molecules with different solvation structures (Figure i) that were suggested by our MD simulations. We initialized their structures based on hemidirected geometries, , in alignment with the preference for hemidirected over holo-directed geometries for complexes with 6–8 water molecules. The optimized structures, presented in Figure i, display an arrangement of water molecules around Pb 2+ similar to that observed in ref .…”