Self-Generated Electrokinetic Fluid Flows during Pseudomorphic Mineral Replacement Reactions.

Area of Science:

• Geochemistry
• Materials Science
• Chemical Engineering

Background:

• Pseudomorphic mineral replacement preserves original texture during phase transformation.
• Macroscopic replacement is understood as dissolution-precipitation, but molecular mechanisms and ion transport roles are unclear.
• Understanding these processes is crucial for geochemistry and materials science.

Purpose of the Study:

• To develop a quantitative framework for pseudomorphic replacement.
• To elucidate the molecular-scale mechanisms of KBr replacement by KCl.
• To investigate the role of ion transport and fluid flow in pseudomorphic mineral replacement reactions (pMRR).

Main Methods:

• Utilized a combination of microscopic and spectroscopic techniques.
• Developed a new quantitative modeling framework.
• Studied the pseudomorphic replacement of KBr in a saturated KCl solution.

Main Results:

• Demonstrated that pseudomorphic mineral replacement (pMRR) is transport-controlled in the KBr-KCl system.
• Identified convective fluid flows, driven by diffusioosmosis, as critical for ion transport.
• Characterized the role of reaction-induced pores in the product phase.

Conclusions:

• Pseudomorphic mineral replacement is significantly influenced by transport phenomena.
• Diffusioosmosis-driven fluid flow is a key mechanism in ion transport during pMRR.
• Findings offer insights into natural mineral transformations and potential industrial applications.