Theoretical Simulation-Guided Development of UiO-66-NH₂ for Ultra-Sensitive Lead Detection in Aquatic Systems Using Atomic Absorption Spectroscopy

Abstract

Lead contamination in aquatic environments poses severe public health risks, necessitating highly sensitive analytical methods for trace-level detection below regulatory limits. This study integrates density functional theory (DFT) calculations and molecular dynamics (MD) simulations with experimental validation to develop a magnetic UiO-66-NH₂ metal-organic framework (MOF) for lead preconcentration. Theoretical simulations guided material optimization and mechanistic understanding, while magnetic solid-phase extraction (SPE) coupled with graphite furnace atomic absorption spectroscopy (GFAAS) provided ultra-sensitive quantification. DFT calculations revealed exceptional Pb²⁺ binding affinity through carboxylate coordination sites (-85.6 kJ/mol). Experimentally, UiO-66-NH₂ achieved maximum adsorption capacity of 320.73 mg/g following pseudo-second-order kinetics and Langmuir isotherm behavior. Magnetic separation enabled rapid processing (<2 minutes) with 200-fold preconcentration. The integrated MOF-SPE-GFAAS method achieved a limit of detection of 0.026 μg/L, significantly below EPA (15 μg/L) and EU (10 μg/L) regulatory thresholds, with excellent recovery rates (98.84-101.30%) across diverse environmental matrices. This theoretical-experimental synergy provides superior analytical performance with practical applicability for environmental monitoring applications.