# Highly Efficient Adsorption of Pb(II) by Magnesium-Modified Zeolite: Performance and Mechanisms

## TL;DR

This study shows that magnesium-modified zeolite can efficiently remove lead from water, even in the presence of other ions, making it a promising solution for water treatment.

## Contribution

The novel approach of magnesium modification significantly enhances the adsorption capacity and stability of zeolite for Pb(II) removal.

## Key findings

- MZ achieved a maximum Pb(II) adsorption capacity of 1656 mg/g.
- MZ maintained high performance in a pH range of 3.0 to 5.5 and with high concentrations of competing ions.
- Mechanistic analysis showed Pb(II) was converted to hydroxycarbonate via surface complexation.

## Abstract

In this study, magnesium-modified clinoptilolite (MZ) was successfully synthesized via precipitation and calcination to efficiently remove Pb(II) from aqueous solutions. The material was systematically characterized using BET, XRD, SEM-EDX, FT-IR, and XPS. Adsorption kinetics followed a pseudo-second-order model (R2 = 0.9956), with MZ removing over 70% of Pb(II) within the first 3 h. Isotherm data were best described by the Langmuir model (R2 = 0.9686), confirming monolayer chemical adsorption, with a maximum adsorption capacity (qm) of 1656 mg/g. Notably, MZ maintained high adsorption capacity across a pH range of 3.0~5.5, and its performance was largely unaffected by the presence of high concentrations of competing ions (0.1~1.0 M NaNO3). Mechanistic analysis revealed that the loaded MgO facilitates the chemical conversion of Pb(II) to hydroxycarbonate (Pb3(CO3)2(OH)2) via surface complexation, which constitutes the primary removal mechanism. These findings demonstrate that magnesium modification can transform natural zeolites into high-capacity, stable adsorbents, offering promising potential for the treatment of Pb(II)-contaminated water.