Supercritical Gallium Trichloride in Oxidative Metal Recycling: Ga₂Cl₆ Dimers vs GaCl₃ Monomers and Rheological...

Area of Science:

• Materials Science
• Chemical Engineering
• Physical Chemistry

Background:

• Oxidative recycling is vital for a circular economy, reducing resource depletion and environmental impact.
• Gallium trichloride (GaCl3) is a potential oxidative solvent for various metals, but its supercritical behavior is unexplored.
• Understanding supercritical GaCl3 is key to advancing recycling technologies.

Purpose of the Study:

• To investigate the molecular structure and viscosity of supercritical gallium trichloride.
• To determine the influence of temperature and pressure on supercritical GaCl3's properties.
• To assess the potential of supercritical GaCl3 for enhanced metal recycling.

Main Methods:

• High-energy X-ray diffraction was employed to probe the structure.
• Multiscale modeling, including first-principles simulations, was utilized.
• Viscosity measurements were performed and compared to existing data.

Main Results:

• Supercritical gallium trichloride displays a dual molecular nature: tetrahedral dimers and trigonal monomers.
• Molecular geometry is controllable via temperature and pressure adjustments.
• Viscosity decreases by 100-fold above the critical temperature, enhancing diffusion.

Conclusions:

• Supercritical GaCl3 possesses a tunable molecular structure suitable for optimized metal recycling.
• The significant reduction in viscosity facilitates rapid molecular diffusion and efficient recycling kinetics.
• This research unlocks potential for advanced, low-temperature, and energy-efficient metal recovery processes.