X-ray fluorescence from a model liquid/liquid solvent extraction system

X-ray fluorescence near total reflection (XFNTR) is measured from the liquid/liquid interface between dodecane and an ErCl3 aqueous solution by monitoring L shell Er emission lines. A custom sample cell is used to minimize absorption of the fluorescence x-rays that pass through dodecane on their way to the detector. The Er3+ concentration near the interface is related to the fluorescence intensity by a scale factor that is extracted by fitting the incident-angle dependent Er La emission line intensities for different ErCl3 bulk concentrations. As an application, we present the use of XFNTR to monitor the growth of interfacial crud in a model solvent extraction system consisting of an interface between a dodecane solution of bis(2-ethylhexyl) phosphate (HDEHP) and an ErCl3 aqueous solution. VC 2011 American Institute of Physics. [doi:10.1063/1.3661983]