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Published on: January 4, 2016
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Bifluoride ([HF2](-)) formation at the fluoridated aluminium hydroxide/water interface
Kenichi Shimizu1, Gordon W Driver2, Marie Lucas2
1Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden. jean-francois.boily@chem.umu.se and Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, OX1 3QZ Oxford, UK.
Dalton Transactions (Cambridge, England : 2003)
|February 26, 2016
Summary
This study reveals bifluoride species forming at mineral surfaces, impacting fluoride removal from solutions. These findings highlight a new inorganic fluorine species at mineral-water interfaces.
Area of Science:
- Geochemistry
- Surface Chemistry
- Environmental Science
Background:
- Mineral surfaces play a critical role in environmental processes.
- Understanding fluoride interactions with minerals is crucial for water treatment and geochemistry.
- Previous studies have not fully characterized bifluoride species at mineral-water interfaces.
Purpose of the Study:
- To investigate the formation and nature of fluoride species at mineral-water interfaces.
- To elucidate the mechanism of fluoride removal by aluminum hydroxide minerals.
- To identify novel inorganic fluorine species in environmental systems.
Main Methods:
- Exposure of gibbsite and bayerite to sodium fluoride solutions.
- Analysis using X-ray photoelectron spectroscopy (XPS) and solid-state 19F nuclear magnetic resonance (NMR).
- Characterization of mineral surface species and their interactions.
Main Results:
- Bifluoride (difluorohydrogenate(I); [HF2](-)) species were identified at aluminum mineral surfaces.
- Fluoride removal is proton-promoted, forming self-buffered suspensions.
- Surface species resemble sodium bifluoride (NaHF2), with proposed structures involving aluminum, fluorine, hydrogen, and sodium.
Conclusions:
- A previously overlooked inorganic fluorine species, bifluoride, forms at mineral-water interfaces.
- These findings have implications for understanding fluoride behavior in geological and engineered systems.
- The study advances knowledge of interfacial chemistry in mineral-water interactions.
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