Bifluoride ([HF2](-)) formation at the fluoridated aluminium hydroxide/water interface.

摘要: This study uncovers bifluoride-type (difluorohydrogenate(I); [HF2]−) species formed at mineral/water interfaces. Bifluoride forms Al–F surface sites resulting from the partial fluoridation of gibbsite (γ-Al(OH3)) and bayerite (α-Al(OH3)) particles exposed to aqueous solutions 50 mM NaF. Fluoride removal these is proton-promoted results in a strongly self-buffered suspensions circumneutral pH, proceeds F : H consumption ratio 2 : 1, with recorded losses up 17 fluoride (58 F nm−2). These loadings exceed crystallographic site densities by factor 3–4, yet reactions have no resolvable impact on particle size, shape mineralogy. X-ray photoelectron spectroscopy (XPS) frozen (−155 °C) wet mineral pastes revealed coexisting F− HF0 species. Electron energy loss features pointed multilayer distribution interface. XPS also uncovered distinct form Na+ involved binding fluoride-bearing solid state magic angle spinning 19F nuclear magnetic resonance measurements showed that were highly comparable sodium-bifluoride (NaHF2) reference. First layer are represented as Al–F–H–F–Al Al–F–Na–F–Al, may multi-layered into consequently point potentially overlooked inorganic fluorine technologically relevant interfacial systems.