Engineered species-selective ion-exchange in tuneable dual-phase zeolite composites

Area of Science:

• Materials Science
• Geochemistry
• Chemical Engineering

Background:

• Controlling sorption selectivity in zeolites is vital for applications like catalysis, gas separation, and ion-exchange.
• Current methods for natural zeolites rely on geological screening, limiting tuneability.
• Developing new methods for engineered zeolite selectivity is essential for industrial applications.

Purpose of the Study:

• To develop a straightforward and tuneable method for achieving sorption selectivity in zeolites.
• To create dual-phase zeolite composites with controlled phase ratios and morphology.
• To demonstrate the dual-cation (strontium and caesium) exchange properties of these composites in nuclear waste management scenarios.

Main Methods:

• Partial interzeolite transformation of natural mordenite to form mordenite/zeolite P composites.
• Characterization of dual-cation exchange properties in complex multi-ion environments.
• In situ X-ray image-guided diffraction experiments to study ion exchange mechanisms.

Main Results:

• Composites exhibited controlled relative uptake of caesium and strontium based on the extent of transformation.
• Engineered composites showed significantly increased ion-exchange affinity for strontium compared to parent mordenite and physical mixtures.
• A 40:60 mordenite:zeolite P composite demonstrated higher uptake rates than clinoptilolite used at Sellafield.

Conclusions:

• Partial interzeolite transformation offers a controllable route to optimize zeolite functionality.
• This strategy enables the engineering of low-cost, high-performance zeolite composites from natural sources.
• The developed composites present formulation advantages for industrial deployment in areas like nuclear waste management.