Insights on selective Pb adsorption via O 2p orbit in UiO-66 containing rich-zirconium vacancies

Herein, we constructed defective UiO-66 with rich Zr vacancy structure model, in which the defective structure was verified by various characterizations. Also, the Pb adsorption experiments affirmed that defective UiO-66 could display better adsorption and selective adsorption ability than that of perfect UiO-66. The results of partial density of states (PDOS) and Mulliken charge population indicated that the blue shift of O 2p and Zr 4d orbit induced the electron rearrangement of atoms closed to the bonding sites, while the positive charge number of Zr atoms decreased than before. Combining with the expansion of pore size, Pb atom was more inclined to transfer and bond with unsaturated coordination oxygens. More significantly, quantitative structure-activity relationships (QSARs) demonstrated that selective capture of Pb instead of Zn, Cu, Cd and Hg displayed by defective UiO-66 was determined jointly by bond strength, adsorption energy and electron transfer. This work provided some theoretical direction for the purpose of the fabrication of adsorbent and the investigation of mechanism. DFT calculations integrated with molecular orbital theory elucidated sorption and selective capture mechanism of adsorbent toward heavy metal ions. [Display omitted]