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Updated: Jan 17, 2026
06:37
Analyzing Melts and Fluids from Ab Initio Molecular Dynamics Simulations with the UMD Package
Published on: September 17, 2021
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An integrated experimental and modeling approach to understand pyromorphite solubility.
Darren A Chevis1, Yongshan Wan1, Kirk G Scheckel2
1U.S. EPA Center for Environmental Measurement and Modeling, Gulf Breeze, FL, 32561, United States.
Chemosphere
|September 20, 2025
Summary
Pyromorphite stability is key for lead remediation. This study found that a small amount of a more soluble lead phase, undetectable by standard methods, significantly impacts pyromorphite
Area of Science:
- Environmental Science
- Geochemistry
- Mineralogy
Background:
- Pyromorphite (Pb5(PO4)3Cl) is a stable lead apatite mineral with potential for lead remediation.
- Accurate solubility data is crucial for effective environmental applications of pyromorphite.
- Previous studies have yielded varying solubility product (Ksp) estimates for pyromorphite.
Purpose of the Study:
- To investigate pyromorphite solubility across a pH range of 2-10.
- To determine the influence of mineral crystallinity and secondary phases on pyromorphite dissolution.
- To improve predictive models for lead release from pyromorphite in environmental settings.
Main Methods:
- Conducted a series of pyromorphite solubility experiments across a pH range of 2-10.
- Utilized Fourier-transform infrared spectroscopy (FTIR) to analyze synthesized pyromorphite crystallinity.
- Employed PHREEQC simulations, incorporating a secondary lead chloride (PbCl2) phase, to model pyromorphite dissolution.
Main Results:
- Calculated a solubility product (Ksp) for pyromorphite of 10^-79.58, influenced by lower crystallinity.
- PHREEQC simulations accurately predicted lead release at acidic pH but underestimated it at neutral pH.
- Including a minor PbCl2 phase (0.2-0.4 wt%) in simulations improved model accuracy up to pH 8.
Conclusions:
- Undetectable amounts of more soluble lead-bearing phases can significantly affect pyromorphite's effective solubility.
- Mineral crystallinity, influenced by aging time, impacts pyromorphite Ksp values.
- Close monitoring of pH during phosphate remediation is necessary to prevent the coprecipitation of more soluble lead minerals.
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