RARE EARTH ELEMENTS ADSORPTION ON KAOLINITE

Rare earth elements (REEs), including yttrium, scandium, and the 15 lanthanide elements, have become prominent areas of focus in the geochemistry field. REEs are used in several alternative energy sources and as geochemical tracers that assist in understanding geochemical processes and paleoenvironments. We plan to perform batch experiments to model the adsorption of five REE (La, Nd, Y, Dy, and Yb) to mineral adsorbent common in geologic settings such as clay minerals. After taking a control sample of the REE in suspension, the mineral adsorbent will be introduced into simulate freshwater with a pH of 6. After 24-hour reaction, REE-loaded mineral particles will be rinsed and resuspended in artificial seawater with pH 8. Throughout the experiment, samples of the reaction suspension will be taken at different time points. At the end of reaction, the solid and final aqueous sample will be collected and analyzed for REE concentration using inductively coupled plasma-mass spectrometry (ICP-MS). The data collected will be analyzed to compare uptake efficiency and affinity of REE to the mineral surfaces, pH edge, and ionic strength. We plan to investigate the behavior of REE adsorption and desorption under varied solution chemistry to simulate the mobilization of REE from freshwater sources to seawater. Understanding and quantifying the desorption rate of REE on clay minerals vs Fe-oxides in different pH settings implies the adsorbent contribution to the marine REE budget.