Ligand design of a novel metal-organic framework for selective capturing of Pb(II) from wastewater

With the increasing pollution of lead in industrial wastewater, many researchers have tried to remove lead ions by various methods. However, while removing lead, some valuable metals are often removed, resulting in loss of economic benefits. It is necessary to develop new materials that can efficiently and selectively remove lead ions without affecting other metals. In this work, a novel Zr-based metal-organic framework adsorbent (UiO-DCCA) is synthesized for the efficient and selective capture of Pb(II) by a novel N,N'-(4carboxylic-pyridine-2,6-diyl) dipicolinimidamide ligand. The selective adsorption experiment shows unique affinity of UiO-DCCA for Pb(II), and the maximum adsorption capacity is 353.29 mg/g. The adsorption mode is single-layer chemical adsorption that conforms with the pseudo-second-order kinetic and Langmuir isotherm models. Density functional theory calculations indicate that the electrostatic interaction of -NH and the chelation of C--N assume a significant part in the adsorption process. This study shows the value of new self-designed organic ligands in metal-organic framework materials that selectively capture heavy metal ions.