# Efficient, Reversible Lead Adsorption in a Thiol‐Decorated Zirconium‐Metal–Organic Framework

## TL;DR

A new material efficiently captures and releases lead ions from water, making it useful for cleaning up heavy metal pollution.

## Contribution

A thiol-decorated Zr-MOF with exceptional Pb(II) adsorption and reversible regeneration is developed and characterized.

## Key findings

- Zr-DMSA captures Pb(II) via mixed S/O chelation through flexible ligands.
- Pb binding is fully reversible under acidic conditions, enabling 10 adsorption–desorption cycles.
- The material effectively removes Pb(II) from perovskite solar cells at various temperatures.

## Abstract

Metal‐organic frameworks (MOFs) featuring high densities of selective metal binding sites represent promising materials for the extraction of toxic metal ions from liquids. This study presents a Zr‐MOF containing accessible thiol functionalities that demonstrates exceptional adsorption capacity and recyclability for the capture of lead(II) ions (Pb(II)). Structural characterization via Pair Distribution Function (PDF) and Powder X‐ray diffraction (PXRD) analyses revealed well‐defined Zr‐clusters interconnected via meso‐2,3‐dimercaptosuccinic acid (DMSA) linkers. The framework exhibits limited long‐range structural order and high ligand flexibility that facilitates Pb(II) chelation. Sequential adsorption/desorption cycles monitored via X‐ray Photoelectron Spectroscopy (XPS), solid‐state NMR, and PDF established that: (i) strong chelation occurs between Pb(II) and DMSA through both thiol and carboxylate functionalities and (ii) this chelation is reversible under acidic conditions, enabling complete adsorbent regeneration. Beyond its high performance in lead removal from water, the practical utility of Zr‐DMSA was further demonstrated through the removal of Pb(II) from damaged Pb‐based perovskite solar cells, with efficacy confirmed at both ambient and elevated temperatures. These results highlight the potential of thiol‐bearing Zr‐MOFs as efficient, cyclable adsorbents for heavy metal remediation applications.

A thiol‐decorated Zr‐MOF, Zr‐DMSA, efficiently captures Pb(II) from water via mixed S/O chelation enabled by flexible “dangling” ligands, as revealed by solid‐state NMR and pair distribution function analyses. Treatment with 1 M HCl fully reverses Pb binding, regenerating the material for up to 10 consecutive adsorption–desorption cycles.