Influence of speciation during membrane treatment of uranium contaminated water

Membrane treatment can be used to selectively remove chemical species from effluents. However, speciation depends on different chemical factors such as inorganic and organic reaction partners, tem-perature, and pH, complicating a deeper understanding of underlying mechanisms. In this study the potential of membrane separation for selective uranium removal was assessed. Speciation for complex chemical conditions in two real water samples was determined independently by predictive speciation modelling, and direct measurement using cryo-TRLFS (time-resolved laser-induced fluorescence spectroscopy). Different nanofiltration membranes and reverse osmosis membranes were characterized for their potential rejection, and pure water flux. The best performing membrane was then employed in cross-flow experiments and reached retentions over 99 % and U/Na-selectivities of 200. Uranium retentions showed a low dependency on feed uranium speciation. Continuing research is necessary for an exact determination of separation mechanisms for each membrane.