Fourier transform infrared and Raman study of Alizarin Red S adsorbed at the fluorite-water interface

The adsorption of 1,2-dihydroxyanthraqinone-3-sulphonate (ARS) onto the sur face of fluorite mineral was studied using diffuse reflectance infrared Fou rier transform (DRIFT) spectroscopy and Fourier transform (FT) Raman spectr oscopy. The FT-Raman method proved to be more appropriate for this study wh en ARS was adsorbed from alkaline solution. At pH 6 both DRIFT and Raman sp ectra indicate non-precipitated ARS on the fluorite surface. At higher pH R aman spectra indicate ARS to be attached to the fluorite surface through th e quinoid group at the 9-position and the or-phenolic oxygen. (C) 1999 Else vier Science B.V. All rights reserved.