In this work, Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra of alkyl hydroxamic acid adsorbed onto the bastnäsite ([Ce,La]FCO3) surface are presented. Spectra are compared with density functional theory models to resolve the mechanism of adsorption. Data indicate a chemisorption interaction that is both pH and concentration dependent. This fundamental understanding of ligand adsorption to mineral surfaces will aid in the development of selective collectors for rare earth ore separation. ATR-FTIR spectroscopy is a valuable tool for probing adsorption of organic compounds to mineral surfaces in-situ. A thin particle film deposited on the internal reflection element (IRE) allows the evanescent wave to reach the mineral-solution interface while reducing the spectral contribution from bulk water. Methods for applying the particle film are adjusted so that its thickness correlates with the penetration depth of the beam. This wavelength-dependent value is determined by the optical properties of the sample-IRE interface. Careful subtraction of the water and mineral background is also necessary to avoid misleading artifacts. Additional factors preclude absolute quantification of the adsorbent, including peak overlap and detector nonlinearity. Results from this work emphasize which insights can be obtained from this methodology and what challenges remain.

ATR-FTIR analysis of ligand adsorption at the mineral-solution interface

255th National Meeting (2018)

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